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目前日期文章:201102 (18)

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日 本物質材料研究機構於今(2010)年10/26公開發表,其將厚度為分子等級的氧化物奈米薄片(nano sheet)交互重疊,成功開發出世界最小的強介電體。新技術在成為強介電體奈米材料設計應用研究方針的同時,對於使用以低電壓便可運作之強介電體奈米薄 膜製成的低耗電記憶體、IC晶片卡之開發也有密不可分的關係。

 

 

圖說:人工超晶格之透過型電子顯微鏡影像

研究團隊利用人工超晶格(Superlattice)技術製造全世界厚度最薄、僅10奈米的薄膜,開發出奈米等級的強介電體。新產品在室溫下展現出優越的強誘電性,這是首次以奈米物質之組合製作出強介電體。

 新 產品擁有與強介電體代表材料之鋯鈦酸鉛(Lead Zirconate Titanate, PZT)類似的構造,並使用兩種不含有毒物質鉛金屬的氧化物奈米薄片將之相互重疊製作人工超晶格。研究團隊讓接合部分的離子變位、容易分極以使新產品擁有 強誘電性。由於這項技術不需要用到薄膜製程主流的大型真空設備或昂貴的成膜裝置,所以能夠以低成本方式進行生產;特別是不必經過熱處理程序,在室溫下就能 製造強介電體薄膜,故可朝玻璃基板、塑膠基板上製作強介電體裝置等用途繼續研究。

 

 

資料來源: 日刊工業新聞/材料世界網編譯

引用出處: 

 http://www.materialsnet.com.tw/DocView.aspx?id=9005

歡迎來到Bewise Inc.的世界,首先恭喜您來到這接受新的資訊讓產業更有競爭力,我們是提供專業刀具製造商,應對客戶高品質的刀具需求,我們可以協助客戶滿足您對產業的不同要求,我們有能力達到非常卓越的客戶需求品質,這是現有相關技術無法比擬的,我們成功的滿足了各行各業的要求,包括:精密HSS DIN切削刀具協助客戶設計刀具流程DIN or JIS 鎢鋼切削刀具設計NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計超高硬度的切削刀具醫療配件刀具設計複合式再研磨機PCD地板專用企口鑽石組合刀具粉末造粒成型機主機版專用頂級電桿PCBN刀具PCD刀具單晶刀具PCD V-Cut捨棄式圓鋸片組粉末成型機航空機械鉸刀主機版專用頂級電汽車業刀具設計電子產業鑽石刀具木工產業鑽石刀具銑刀與切斷複合再研磨機銑刀與鑽頭複合再研磨機銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計;從微細刀具到大型刀具;從小型生產到大型量產;全自動整合;我們的技術可提供您連續生產的效能,我們整體的服務及卓越的技術,恭迎您親自體驗!!  

BW Bewise Inc. Willy Chen willy@tool-tool.com  bw@tool-tool.com  www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com/ / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting toolaerospace tool .HSS  DIN Cutting toolCarbide end millsCarbide cutting toolNAS Cutting toolNAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end milldisc milling cutter,Aerospace cutting toolhss drillФрезерыCarbide drillHigh speed steelCompound SharpenerMilling cutterINDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) Core drillTapered end millsCVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden FingerPCD V-CutterPCD Wood toolsPCD Cutting toolsPCD Circular Saw BladePVDD End Millsdiamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE Single Crystal Diamond Metric end millsMiniature end millsСпециальные режущие инструменты Пустотелое сверло Pilot reamerFraisesFresas con mango PCD (Polycrystalline diamond) ‘FresePOWDER FORMING MACHINEElectronics cutterStep drillMetal cutting sawDouble margin drillGun barrelAngle milling cutterCarbide burrsCarbide tipped cutterChamfering toolIC card engraving cutterSide cutterStaple CutterPCD diamond cutter specialized in grooving floorsV-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert PCD Diamond Tool Saw Blade with Indexable InsertNAS toolDIN or JIS toolSpecial toolMetal slitting sawsShell end millsSide and face milling cuttersSide chip clearance sawsLong end millsend mill grinderdrill grindersharpenerStub roughing end millsDovetail milling cuttersCarbide slot drillsCarbide torus cuttersAngel carbide end millsCarbide torus cuttersCarbide ball-nosed slot drillsMould cutterTool manufacturer. 

Bewise Inc.  www.tool-tool.com

ようこそBewise Inc.の世界へお越し下さいませ、先ず御目出度たいのは新たな

情報を受け取って頂き、もっと各産業に競争力プラス展開。

弊社は専門なエンドミルの製造メーカーで、客先に色んな分野のニーズ

豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。

弊社は各領域に供給できる内容は:

(1)精密HSSエンドミルのR&D

(2)Carbide Cutting tools設計

(3)鎢鋼エンドミル設計

(4)航空エンドミル設計

(5)超高硬度エンドミル

(6)ダイヤモンドエンドミル

(7)医療用品エンドミル設計

(8)自動車部品&材料加工向けエンドミル設計

弊社の製品の供給調達機能は:

(1)生活産業~ハイテク工業までのエンドミル設計

(2)ミクロエンドミル~大型エンドミル供給

(3)小Lot生産~大量発注対応供給

(4)オートメーション整備調達

(5)スポット対応~流れ生産対応

弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。   

Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz.

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт  www.tool-tool.com  для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web  www.tool-tool.com  for more info.

 

beeway 發表在 痞客邦 PIXNET 留言(0) 人氣()

日本產業技術總合研究所秋山守人組長所領軍的研究團隊開發出可耐熱攝氏1000千度以上高溫之金屬薄膜製造技術。研究團隊先做出兩種金屬薄膜,然後再將之製為合金。

 以 往的薄膜只要超過攝氏1000度就容易與空氣中的氧氣或氮氣進行化學反應,因此存在著會自貼附的基板上剝離的問 題。新開發的製造方法則是在耐熱材料氧化鋯基板上製作厚度約100奈米的釕(ruthenium)薄膜,然後於釕薄膜上方製作同樣厚度的鎢 (tungsten)薄膜;最後再以攝氏1450度加熱一個小時,使釕與鎢結合為合金。研究團隊藉由加熱實驗來確保新產品的導電性並確認不會有剝離或破碎 的情況發生。假使以其他的鉑系元素如銠(Rhodium)或鉑來取代釕、以鉻(chromium)或鎳(Nickel)等其他高熔點的金屬來取代鎢的話, 也能夠達到同樣的性能。

噴射引擎、發電用渦輪、鐵工廠高溫爐等周邊往往都超過攝氏 1000度高溫,為了檢測故障狀況便需要可長時間調查震動 或壓力等的感應器;然而一直以來卻沒有可用於1000度以上的感應器,所以必須要先停止機器的運轉後才能進行檢查。此次開發的新產品除將以高溫環境異常檢 測感應器之電極為應用目標外,研究團隊今後也將以開發可耐攝氏2000度以上的金屬薄膜為主要研究方向。

 

 

資料來源: 日經產業新聞/材料新聞網編譯

引用出處: 

 http://www.materialsnet.com.tw/DocView.aspx?id=9127

歡迎來到Bewise Inc.的世界,首先恭喜您來到這接受新的資訊讓產業更有競爭力,我們是提供專業刀具製造商,應對客戶高品質的刀具需求,我們可以協助客戶滿足您對產業的不同要求,我們有能力達到非常卓越的客戶需求品質,這是現有相關技術無法比擬的,我們成功的滿足了各行各業的要求,包括:精密HSS DIN切削刀具協助客戶設計刀具流程DIN or JIS 鎢鋼切削刀具設計NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計超高硬度的切削刀具醫療配件刀具設計複合式再研磨機PCD地板專用企口鑽石組合刀具粉末造粒成型機主機版專用頂級電桿PCBN刀具PCD刀具單晶刀具PCD V-Cut捨棄式圓鋸片組粉末成型機航空機械鉸刀主機版專用頂級電汽車業刀具設計電子產業鑽石刀具木工產業鑽石刀具銑刀與切斷複合再研磨機銑刀與鑽頭複合再研磨機銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計;從微細刀具到大型刀具;從小型生產到大型量產;全自動整合;我們的技術可提供您連續生產的效能,我們整體的服務及卓越的技術,恭迎您親自體驗!!  

BW Bewise Inc. Willy Chen willy@tool-tool.com  bw@tool-tool.com  www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com/ / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting toolaerospace tool .HSS  DIN Cutting toolCarbide end millsCarbide cutting toolNAS Cutting toolNAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end milldisc milling cutter,Aerospace cutting toolhss drillФрезерыCarbide drillHigh speed steelCompound SharpenerMilling cutterINDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) Core drillTapered end millsCVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden FingerPCD V-CutterPCD Wood toolsPCD Cutting toolsPCD Circular Saw BladePVDD End Millsdiamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE Single Crystal Diamond Metric end millsMiniature end millsСпециальные режущие инструменты Пустотелое сверло Pilot reamerFraisesFresas con mango PCD (Polycrystalline diamond) ‘FresePOWDER FORMING MACHINEElectronics cutterStep drillMetal cutting sawDouble margin drillGun barrelAngle milling cutterCarbide burrsCarbide tipped cutterChamfering toolIC card engraving cutterSide cutterStaple CutterPCD diamond cutter specialized in grooving floorsV-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert PCD Diamond Tool Saw Blade with Indexable InsertNAS toolDIN or JIS toolSpecial toolMetal slitting sawsShell end millsSide and face milling cuttersSide chip clearance sawsLong end millsend mill grinderdrill grindersharpenerStub roughing end millsDovetail milling cuttersCarbide slot drillsCarbide torus cuttersAngel carbide end millsCarbide torus cuttersCarbide ball-nosed slot drillsMould cutterTool manufacturer.

Bewise Inc.  www.tool-tool.com

ようこそBewise Inc.の世界へお越し下さいませ、先ず御目出度たいのは新たな

情報を受け取って頂き、もっと各産業に競争力プラス展開。

弊社は専門なエンドミルの製造メーカーで、客先に色んな分野のニーズ

豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。

弊社は各領域に供給できる内容は:

(1)精密HSSエンドミルのR&D

(2)Carbide Cutting tools設計

(3)鎢鋼エンドミル設計

(4)航空エンドミル設計

(5)超高硬度エンドミル

(6)ダイヤモンドエンドミル

(7)医療用品エンドミル設計

(8)自動車部品&材料加工向けエンドミル設計

弊社の製品の供給調達機能は:

(1)生活産業~ハイテク工業までのエンドミル設計

(2)ミクロエンドミル~大型エンドミル供給

(3)小Lot生産~大量発注対応供給

(4)オートメーション整備調達

(5)スポット対応~流れ生産対応

弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。   

Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz.

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт  www.tool-tool.com  для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web  www.tool-tool.com  for more info.

 

beeway 發表在 痞客邦 PIXNET 留言(0) 人氣()

度 钢-钢粘接强度(Mpa) 21

抗拉强度(Mpa) 42 钢-钢剪切强度(Mpa) 16

弹性模量(Mpa) 1.5×10³ 钢- 砼粘接强度(Mpa) 3.5

伸长率(%) 1.7

可操作时间(min) 40 接触干时间(20℃ h) 1.5

推荐比例(重量比) 甲:乙=2:1

 

 

 

该产品各项性能指标均符合《混凝土结构加固设计规范》(GB50367-2006)中A级要求

 

使用说明

1. 基层要求:粘结面必须平整、坚实、无杂质,修补胶已经硬化,且表面干燥,没有露水、冰霜等。

2. 调胶:按照粘结面积计算用量,准确称取甲、乙组份,在一清洁容器中充分搅拌均匀。调好的胶应在适用期内用完。

3. 涂刷底胶:将按比列混合均匀的MT-202碳纤维底胶直接涂刷到混凝土基层上,混凝土的表面应含胶饱满。硬化后进行下一道工序。

4. 粘贴碳纤维:

① 用硬毛刷将调好的MT-202浸渍胶均匀地涂刷到粘贴结面上,胶量必须充足、饱满。涂刷量约300~500g∕㎡。

② 将裁好的碳纤维布贴于混凝土粘贴面,使用硬橡胶棍或塑料刮板往复碾压,促使碳纤维平直、延展,粘合剂充分渗透。碳纤维布长向上接头搭长度应为10-20cm。

③ 在碳纤维表面部分涂刷粘合剂,继续往复刮涂碾压,赶出气泡,并使粘合剂均匀覆盖碳纤维布。涂刷量约200 g∕㎡.

④ 静置1-2小时至指干,重复碾压消除因碳纤维浮起或错开可能引起的气泡、粘结布实等。

⑤ 多层粘粘,可重复以上操作。

⑥ 粘合剂固化后,在被粘贴的碳纤维表面上再刮涂一层胶。

 

施工要点

施工前用根据环境、温度、工艺等综合情况试验调制最佳配方

用金刚片打磨混凝土表面,直至露出沙石新面层,再将灰尘清洗干净

粘贴碳纤维片材时要使浸渍胶充分浸透片材并且布得损伤碳纤维片材

 

注意事项

1、 配胶时,应在适当的通风环境下进行。

2、 操作人员使用安全镜,配戴防护面罩。

3、 雨天、霜雾天气不得进行户外施工。

4、 碳纤维是导电纤维,因此,施工操作时必须远离电源,避免发生触电伤亡事故。户外靠近带电体(电线等)施工时,如果风大应停止施工,以免碳纤维布被风刮起接触导电体而发生事故。

5、 碳纤维布纤维方向为单方向,单位重量、厚度、抗拉强度、弹性模量等各项指标必须符合有关要求。

 

包装贮存

1、 密封包装,存放或使用时必须远离火源,避免日光直射。

2、 包装规格:甲:14公斤∕桶,乙:7公斤∕桶。

 

典型工程应用

荷华大厦粘碳纤维加固改造

团中央粘碳纤维布加固改造工程

 

引用出處: 

 http://www.hudong.com/wiki/%E7%B2%98%E8%B4%B4%E7%A2%B3%E7%BA%A4%E7%BB%B4%E8%83%B6

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Tellurium ( /tɪˈlʊəriəm/ or /tɛˈl(j)ʊəriəm/ te-LOOR-ee-əm) is a chemical element that has the symbol Te and atomic number 52. A brittle, mildly toxic, silver-white metalloid which looks similar to tin, tellurium is chemically related to selenium and sulfur. Tellurium was discovered in 1782 by Franz-Joseph Müller von Reichenstein in a mineral containing gold and tellurium. Martin Heinrich Klaproth named the new element in 1798 after the Latin word for "earth", tellus.

Although several gold deposits contain tellurium minerals, the main commercial source for tellurium is as a by-product of copper and lead production. Tellurium is primarily used in alloys, foremost in steel and copper to improve machinability. Applications in solar panels and as a semiconductor material also consume a considerable fraction of tellurium production.

Tellurium has no biological function, although fungi can incorporate it in place of sulfur and selenium into amino acids such as telluro-cysteine and telluro-methionine.[3] In humans, tellurium is partly metabolized into dimethyl telluride, (CH3)2Te, a gas with a garlic-like odor which is exhaled in the breath of victims of tellurium toxicity or exposure.

 

 

Contents

[hide]

  • 1 Characteristics
    • 1.1 Physical properties
    • 1.2 Chemical properties
    • 1.3 Isotopes
    • 1.4 Occurrence
  • 2 Production
  • 3 Compounds
  • 4 History
  • 5 Applications
    • 5.1 Metallurgy
    • 5.2 Semiconductor and electronic industry uses
    • 5.3 Other uses
  • 6 Biological role
  • 7 Precautions
  • 8 References
  • 9 External links

[edit] Characteristics

[edit] Physical properties

When crystalline, tellurium is silvery-white and when it is in pure state it has a metallic luster. It is a brittle and easily pulverized metalloid. Amorphous tellurium is found by precipitating it from a solution of tellurous or telluric acid (Te(OH)6).[4] Tellurium is a p-type semiconductor that shows a greater electrical conductivity in certain directions which depends on atomic alignment; the conductivity increases slightly when exposed to light (photoconductivity).[5] When in its molten state, tellurium is corrosive to copper, iron and stainless steel.

[edit] Chemical properties

Tellurium adopts a polymeric structure, consisting of zig-zag chains of Te atoms. This gray material resists oxidation by air and is nonvolatile.

[edit] Isotopes

Main article: Isotopes of tellurium

Naturally occurring tellurium has eight isotopes. Four of those isotopes, 122Te, 124Te, 125Te and 126Te, are stable. The other four, 120Te, 123Te, 128Te and 130Te, have been observed to be radioactive.[6][7] The stable isotopes make up only 33.2 % of the naturally occurring tellurium; this is possible due to the long half-lives of the unstable isotopes. They are in the range from 1013 to 2.2 1024 years. This makes 128Te the isotope with the longest half life among all radioisotopes.[8]

There are 38 known nuclear isomers of tellurium with atomic masses that range from 105 to 142. Tellurium is the lightest element known to undergo alpha decay, with isotopes 106Te to 110Te being able to undergo this mode of decay.[6] The atomic mass of tellurium (127.60 g·mol−1) exceeds that of the following element iodine (126.90 g·mol−1).[9]

[edit] Occurrence

 

See also Category: Telluride minerals

 

 

 

 

Tellurium on quartz (Moctezuma, Sonora, Mexico)

With an abundance in the Earth's crust comparable to that of platinum, tellurium is one of the rarest stable solid elements in the Earth's crust. Its abundance is about 1 µg/kg.[10] In comparison, even the rarest of the lanthanides have crustal abundances of 500 µg/kg (see Abundance of the chemical elements).[11]

The extreme rarity of tellurium in the Earth's crust is not a reflection of its cosmic abundance, which is in fact greater than that of rubidium, even though rubidium is ten thousand times more abundant in the Earth's crust. The extraordinarily low abundance of tellurium on Earth is rather thought to be due to conditions in the Earth's formation, when the stable form of certain elements, in the absence of oxygen and water, was controlled by the reductive power of free hydrogen. Under this scenario, certain elements such as tellurium which form volatile hydrides were severely depleted during the formation of the Earth's crust, through evaporation of these hydrides. Tellurium and selenium are the heavy elements most depleted in the Earth's crust by this process.[citation needed]

Tellurium is sometimes found in its native (elemental) form, but is more often found as the tellurides of gold (calaverite, krennerite, petzite, sylvanite and others). Tellurium compounds are the most common chemical compounds of gold found in nature (rare non-tellurides such as gold aurostibite and bismuthide are known). Tellurium is also found combined with elements other than gold, in salts of other metals. In contrast to selenium, tellurium is not able to replace sulfur in its minerals. This is due to the large difference in ion radius of sulfur and tellurium. In consequence, many sulfide minerals contain considerable amounts of selenium, but only traces of tellurium.[12]

In the gold rush of 1893, diggers in Kalgoorlie discarded a pyritic material which got in their way as they searched for pure gold. The Kalgoorlie waste was thus used to fill in potholes or as part of sidewalks. Three years passed before it was realized that this waste was calaverite, a telluride of gold that had not been recognized. This led to a second gold rush in 1896 which included mining the streets.[13]

[edit] Production

The principal source of tellurium is from anode sludges produced during the electrolytic refining of blister copper. It is a component of dusts from blast furnace refining of lead. Treatment of 500 tons of copper ore typically yields one pound (0.45 kg) of tellurium. Tellurium is produced mainly in the United States, Peru, Japan, and Canada.[14] For the year 2006 the British Geological Survey gives the following numbers: United States 50 t, Peru 37 t, Japan 24 t and Canada 11 t.[15]

 

 

 

 

Tellurium production 2006

The anode sludges contain the selenides and tellurides of the noble metals in compounds with the formula M2Se or M2Te (M = Cu, Ag, Au). At temperatures of 500 °C the anode sludges are roasted with sodium carbonate under air. The metal ions are reduced to the metals, while the telluride is converted to sodium tellurite.[16]

 

M2Te + O2 + Na2CO3 → Na2TeO3 + 2 M + CO2

Tellurites can be leached from the mixture with water and are normally present as hydrotellurites HTeO3- in solution. Selenites are also formed during this process, but they can be separated by adding sulfuric acid. The hydrotellurites are converted into the insoluble tellurium dioxide while the selenites stay in solution.[16]

 

HTeO3- + OH- + H2SO4 → TeO2 + 2 SO42− + 2 H2O

The reduction to the metal is done either by electrolysis or by reacting the tellurium dioxide with sulfur dioxide in sulfuric acid.[16]

 

TeO2 + 2 SO2 + 2H2O → Te + SO42− + 4 H+

Commercial-grade tellurium is usually marketed as minus 200-mesh powder but is also available as slabs, ingots, sticks, or lumps. The year-end price for tellurium in 2000 was US$14 per pound. In recent years, the tellurium price was driven up by increased demand and limited supply, reaching as high as US$100 per pound in 2006.[17][18]

[edit] Compounds

 

See also Category: Tellurium compounds

Tellurium belongs to the same chemical family as oxygen, sulfur, selenium and polonium: the chalcogen family. Tellurium and selenium compounds are similar. It exhibits the oxidation states −2, +2, +4 and +6, with the +4 state being most common.[4]

 

Tellurides

Reduction of Te metal produces the Tellurides and polytellurides, Ten2-. The −2 oxidation state is exhibited in binary compounds with many metals, such as zinc telluride, ZnTe, formed by heating tellurium with zinc.[19] Decomposition of ZnTe with hydrochloric acid yields hydrogen telluride (H2Te), a highly unstable analogue of the other chalcogen hydrides, H2O, H2S and H2Se:

 

ZnTe + 2 HCl → ZnCl2 + H2Te

H2Te is unstable, whereas salts of its conjugate base [TeH]- are stable.

 

Halides

The +2 oxidation state is exhibited by the dihalides, TeCl2, TeBr2 and TeI2. The dihalides have not been obtained in pure form,[20]:274 although they are known decomposition products of the tetrahalides in organic solvents, and their derived tetrahalotellurates are well-characterized:

 

Te + X2 + 2 X− → TeX2−

4

 

where X is Cl, Br, or I. These anions are square planar in geometry.[20]:281 Polynuclear anionic species also exist, such as the dark brown Te2I2−

6,[20]:283 and the black Te4I2−

14.[20]:285

 

Fluorine forms two halides with tellurium: the mixed-valence Te2F4 and TeF6. In the +6 oxidation state, the –OTeF5 structural group occurs in a number of compounds such as HOTeF5, B(OTeF5)3, Xe(OTeF5)2, Te(OTeF5)4 and Te(OTeF5)6.[21] The square antiprismatic anion TeF2−

8 is also attested.[16] The other halogens do not form halides with tellurium in the +6 oxidation state, but only tetrahalides (TeCl4, TeBr4 and TeI4) in the +4 state, and other lower halides (Te3Cl2, Te2Cl2, Te2Br2, Te2I and two forms of TeI). In the +4 oxidation state, halotellurate anions are known, such as TeCl2−

6 and Te2Cl2−

10. Halotellurium cations are also attested, including TeI+

3, found in TeI3AsF6.[22]

 

Oxocompounds

 

 

 

 

A sample of tellurium dioxide powder

Tellurium monoxide was first reported in 1883 as a black amorphous solid formed by the heat decomposition of TeSO3 in vacuum, disproportionating into tellurium dioxide, TeO2 and elemental tellurium upon heating.[23][24] Since then, however, some doubt has been cast on its existence in the solid phase, although it is known as a vapor phase fragment; the black solid may be merely an equimolar mixture of elemental tellurium and tellurium dioxide.[25]

 

Tellurium dioxide is formed by heating tellurium in air, causing it to burn with a blue flame.[19] Tellurium trioxide, β-TeO3, is obtained by thermal decomposition of Te(OH)6. The other two forms of trioxide reported in the literature, the α- and γ- forms, were found not to be true oxides of tellurium in the +6 oxidation state, but a mixture of Te4+, OH− and O−

2.[26] Tellurium also exhibits mixed-valence oxides, Te2O5 and Te4O9.[26]

 

The tellurium oxides and hydrated oxides form a series of acids, including tellurous acid (H2TeO3), orthotelluric acid (Te(OH)6) and metatelluric acid ((H2TeO4)n).[25] The two forms of telluric acid form tellurate salts containing the TeO2–

4 and TeO6−

6 anions, respectively. Tellurous acid forms tellurite salts containing the anion TeO2−

3. Other tellurium cations include TeF2+

8, which consists of two fused tellurium rings and the polymeric TeF2+

7.

 

Zintl cations

 

When tellurium is treated with concentrated sulfuric acid, it forms red solutions containing the Zintl ion, Te2+

4.[27] The oxidation of tellurium by AsF5 in liquid SO2 also produces this square planar cation, as well as with the trigonal prismatic, yellow-orange Te4+

6:[16]

 

4 Te + 3 AsF5 → Te2+

4(AsF−

6)2 + AsF3

6 Te + 6 AsF5 → Te4+

6(AsF−

6)4 + 2 AsF3

 

Other tellurium Zintl cations include the polymeric Te2+

7 and the blue-black Te2+

8, which consists of two fused 5-membered tellurium rings. The latter cation is formed by the reaction of tellurium with tungsten hexachloride:[16]

 

8 Te + 2 WCl6 → Te2+

8(WCl−

6)2

 

Interchalcogen cations also exist, such as Te2Se2+

6 (distorted cubic geometry) and Te2Se2+

8. These are formed by oxidizing mixtures of tellurium and selenium with AsF5 or SbF5.[16]

 

Organotellurium compounds

Main article: Organotellurium chemistry

Tellurium does not readily form analogues of alcohols and thiols, with the functional group –TeH and are called tellurols. The –TeH functional group is also attributed to using the prefix tellanyl-.[28] Like H2Te, these species are unstable with respect to loss of H2. Telluraethers (R-Te-R) are more stable as are telluroxides.

[edit] History

 

 

 

 

Klaproth named the new element and credited von Reichenstein with its discovery

Tellurium (Latin tellus meaning "earth") was discovered in the 18th century in a gold ore from the mines in Zlatna, near what is now Sibiu, Transylvania. This ore was known as "Faczebajer weißes blättriges Golderz" (white leafy gold ore from Faczebaja) or antimonalischer Goldkies (antimonic gold pyrite), and, according to Anton von Rupprecht, was Spießglaskönig (argent molybdique), containing native antimony.[29][30] In 1782 Franz-Joseph Müller von Reichenstein, who was then serving as the Austrian chief inspector of mines in Transylvania, concluded that the ore did not contain antimony, but that it was bismuth sulfide.[31] The following year, he reported that this was erroneous and that the ore contained mostly gold and an unknown metal very similar to antimony. After a thorough investigation which lasted for three years and consisted of more than fifty tests, Müller determined the specific gravity of the mineral and noted the radish-like odor of the white smoke which passed off when the new metal was heated, the red color which the metal imparts to sulfuric acid, and the black precipitate which this solution gives when diluted with water. Nevertheless, he was not able to identify this metal and gave it the names aurum paradoxium and metallum problematicum, as it did not show the properties predicted for the expected antimony.[32][33][34]

In 1789, another Hungarian scientist, Pál Kitaibel, also discovered the element independently in an ore from Deutsch-Pilsen which had been regarded as argentiferous molybdenite, but later he gave the credit to Müller. In 1798, it was named by Martin Heinrich Klaproth who earlier isolated it from the mineral calaverite.[33][34][35]

Tellurium was used as a chemical bonder in the making of the outer shell of the first atomic bomb. The 1960s brought growth in thermoelectric applications for tellurium, as well as its use in free-machining steel, which became the dominant use.[citation needed]

[edit] Applications

[edit] Metallurgy

The largest consumer of tellurium is metallurgy, where it is used in iron, copper and lead alloys. When added to stainless steel and copper it makes these metals more machinable. It is alloyed into cast iron for promoting chill for spectroscopic purposes, as the presence of electrically conductive free graphite tends to deleteriously affect spark emission testing results. In lead it improves strength and durability and decreases the corrosive action of sulfuric acid.[36]

[edit] Semiconductor and electronic industry uses

 

 

 

 

A CdTe photovoltaic array

Tellurium is used in cadmium telluride (CdTe) solar panels. National Renewable Energy Laboratory lab tests using this material achieved some of the highest efficiencies for solar cell electric power generation. Massive commercial production of CdTe solar panels by First Solar in recent years has significantly increased tellurium demand.[37][38][39] If some of the cadmium in CdTe is replaced by zinc then (Cd,Zn)Te is formed which is used in solid-state x-ray detectors.[40]

Alloyed with both cadmium and mercury, to form mercury cadmium telluride, an infrared sensitive semiconductor material is formed.[41] Organotellurium compounds such as dimethyl telluride, diethyl telluride, diisopropyl telluride, diallyl telluride and methyl allyl telluride are used as precursors for Metalorganic vapor phase epitaxy growth of II-VI compound semiconductors.[42] Diisopropyl telluride (DIPTe) is employed as the preferred precursor for achieving the low-temperature growth of CdHgTe by MOVPE.[43] For these processes highest purity metalorganics of both selenium and tellurium are used. The compounds for semiconductor industry and are prepared by adduct purification.[44][45]

Tellurium as a tellurium suboxide is used in the media layer of several types of rewritable optical discs, including ReWritable Compact Discs (CD-RW), ReWritable Digital Video Discs (DVD-RW) and ReWritable Blu-ray Discs.[46][47]

Tellurium is used in the new phase change memory chips.[48] developed by Intel.[49] Bismuth telluride (Bi2Te3) and lead telluride are working elements of thermoelectric devices. Lead telluride is used in far-infrared detectors.

[edit] Other uses

  • Used to color ceramics.[50]
  • The strong increase in optical refraction upon the addition of selenides and tellurides into glass is used in the production of glass fibers for telecommunications. These chalcogenide glasses are widely used.[51][52]
  • Mixtures of Selenium and tellurium are used with barium peroxide as oxidizer in the delay powder of electric blasting caps.[53]
  • Organic tellurides have been employed as initiators for living radical polymerization and electron-rich mono- and di-tellurides possess antioxidant activity.
  • Rubber can be vulcanized with tellurium instead of sulfur or selenium. The rubber produced in this way shows improved heat resistance.[54]
  • Tellurite agar is used to identify member of the corynebacterium genus, most typically Corynebacterium diphtheriae, the pathogen responsible for diphtheria.[55]

[edit] Biological role

Tellurium has no known biological function, although fungi can incorporate it in place of sulfur and selenium into amino acids such as telluro-cysteine and telluro-methionine.[citation needed] Organisms have shown a highly variable tolerance to tellurium compounds. Most organisms metabolize tellurium partly to form dimethyl telluride although dimethyl ditelluride is also formed by some species. Dimethyl telluride has been observed in hot springs at very low concentrations.[56][57][58]

[edit] Precautions

Tellurium and tellurium compounds are considered to be mildly toxic and need to be handled with care, although acute poisoning is rare.[59] Tellurium is not reported to be carcinogenic.[59]

Humans exposed to as little as 0.01 mg/m3 or less in air develop "tellurium breath", which has a garlic-like odor.[50] The garlic odor that is associated with human intake of tellurium compounds is caused from the tellurium being metabolized by the body. When the body metabolizes tellurium in any oxidation state, the tellurium gets converted into dimethyl telluride, (CH3)2Te, which is volatile and is the cause of the garlic-like smell. Even though the metabolic pathways of tellurium are not known, it is generally assumed that they resemble those of the more extensively studied selenium, because the final methylated metabolic products of the two elements are similar.[60][61][62]

 

 

 

引用出處: 

 http://en.wikipedia.org/wiki/Tellurium

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碲,原子序数 52,原子量127.60,元素名来源于拉丁文,原意是“地球”。 碲1782年赖兴施泰因在含金的矿石中发现碲。碲在地壳中的含量为千万分之二,主要矿物有针碲金矿、叶碲矿、碲银矿等。碲为银白色有金属光泽的固体,熔点 452°C,沸点1390°C,密度6.25克/厘米3;有两种同素异形体:无定形碲和晶体碲。

纠错 编辑摘要

目录

  • 1 概述
  • 2 性质
  • 3 元素描述
  • 4 发现
  • 5 资源
  •  

  • 1 概述
  • 2 性质
  • 3 元素描述
  • 4 发现
  • 5 资源
  • 6 制取
  • 7 用途

 

碲 - 概述

 

碲 是一种化学元素,它的化学符号是Te,它的原子序数是52,碲(音帝):TELLURIUM,源自tellus意为“土地”。1782年发现。除了兼具金 属和非金属的 特性外,碲还有几点不平常的地方:它在周期表的位置形成“颠倒是非”的现象-碲比碘的原子序数低,具有较大的原子量。如果人吸入它的蒸气,从嘴里呼出的气 会有一股蒜味。碲是稀散金属之一,有两种同素异形体,一种为结晶形,具有银白色金属光泽;另一种为无定形,为黑色粉末。结晶形碲的熔点为449.8℃,沸 点990℃,密度为6.24克/厘米3。碲在常温下性脆,加热后可挤压加工,碲晶体的许多物理性质,如强度、热膨胀、光吸收、电导率、电磁性等都具有各向 异性。碲及其合金和金属间化合物都具有半导体和温差性能,碲单晶的禁带宽度为0.32eV,电子迁移率为9x10-2m2/(V"s),空穴迁移率为 5.9x10-2m2/(V"s),常温电阻率4.36x105SZ'm,碲的薄膜呈红棕色到紫色,能透过红外线而不透过可见光,碲的光电效应微弱,仅为 灰硒的0.01%0碲的外电子层构型为[Kr]4d105s25p4,有-2.0,+2,+4,+6多种价态,其中+4价化合物最稳定。碲的化学性质与硒 相似,碲在常温空气中较稳定,在空气或氧中燃烧生成二氧化碲,发出蓝色火焰;易和卤素剧烈反应生成碲的卤化物,在高温下不与氢作用。碲不与水和无氧化性酸 作用,不溶于盐酸,可溶于热浓硫酸、硝酸和存在氧化剂的苛性碱中。碲不与氢、碳、氮等作用,碲与硫在熔融状态下可以互溶,碲几乎能与所有的金属反应生成碲 化物,碱金属碲化物可溶于水,重金属碲化物不溶于水。二氧化碲具有两性性质。碲易生成亚碲酸(H2TeO3),碲酸(H2TeO4)、正碲酸 (H2TeO6)和相应的碲酸盐。碲-128及碲-130是最常见的碲同位素,但它们都有微弱的放射性。主要用作合金及半导体。碲化铋用作热电装置中。碲 是制造碲化镉太阳能薄膜电池的主要原料。

 

碲 - 性质

 

元素名称:碲

元素符号:Te

元素英文名称:TELLURIUM

元素类型:非金属元素

原子体积:(立方厘米/摩尔):20.5

碲锭

元素在海水中的含量:(ppm)

太平洋表面  0.00000019

地壳中含量:(ppm):0.005

相对原子质量:127.6

原子序数:52

质子数:52

摩尔质量:128

所属周期:5

所属族数:VIA

电子层排布: 2-8-18-18-6

晶体结构:晶胞为六方晶胞。

氧化态:Main  Te+4

Other  Te-2, Te-1, Te0, Te+2, Te+5, Te+6

 

化学键能: (kJ /mol)

Te-H  240

Te-O  268

Te-F  335

Te-Cl  251

Te-Te  235

 

晶胞参数:

a = 445.72 pm

b = 445.72 pm

c = 592.9 pm

α = 90°

β = 90°

γ = 120°

 

莫氏硬度:2.25 

声音在其中的传播速率:(m/S):2610

碲铜棒

电离能 (kJ /mol) 

M - M+ 869.2

M+ - M2+ 1795

M2+ - M3+ 2698

M3+ - M4+ 3610

M4+ - M5+ 5668

M5+ - M6+ 6822

M6+ - M7+ 13200

M7+ - M8+ 15800

M8+ - M9+ 18500

M9+ - M10+ 21200

 

碲 - 元素描述

有 结晶形和无定形两种同素异形体。电离能9.009电子伏特。结晶碲具有银白色的金属外 观,密度6.25克/厘米3,熔点452℃,沸点1390℃,硬度是2.5(莫氏硬度)。不溶于同它不发生反应的所有溶剂,在室温时它的分子量至今还不清 楚。无定形碲(褐色),密度6.00克/厘米3,熔点449.5±0.3℃,沸点989.8±3.8℃。碲在空气中燃烧带有蓝色火焰,生成二氧化碲;可与 卤素反应,但不与硫、硒反应。溶于硫酸、硝酸、氢氧化钾和氰化钾溶液。易传热和导电。

 

碲 - 发现

 

碲(te)

 

1782年德要矿物学家米勒•冯•赖兴施泰因在研究德国金矿石时,得到一种未知物质。1798年德国人克拉普罗特证实了此发现,并测定了这一物质的特性,按拉丁文Tellus(地球)命名为tellurium。

碲 在自然界有一种同金在一起的合金。1782年奥地利首 都维也纳一家矿场监督牟勒从这种矿石中提取出碲,最初误认为是锑,后来发现它的性质与锑不同,因而确定是一种新金属元素。为了获得其他人的证实,牟勒曾将 少许样品寄交瑞典化学家柏格曼,请他鉴定。由于样品数量太少,柏格曼也只能证明它不是锑而已。牟勒的发现被忽略了16年后,1798年1月25日克拉普罗 特在柏林科学院宣读一篇关于特兰西瓦尼亚的金矿论文时,才重新把这个被人遗忘的元素提出来。他将这种矿石溶解在王水中,用过量碱使溶液部分沉淀,除去金和 铁等,在沉淀中发现这一新元素,命名为tellurium(碲),元素符号定为Te。这一词来自拉丁文tellus(地球)。克拉普罗特一再申明,这一新 元素是1782年牟勒发现的。

 

碲 - 资源

碲的地壳丰度为 lx10-7%,查明储量16万吨,主要分布在美国、加拿大、中国、智利等国家。尚未发现有碲的独立工业矿物。碲矿资源分布稀散,多伴生在其它矿物中或以 杂质形式存在于其它矿中。中国四川石棉县大水沟碲矿是至今发现的唯一碲独立矿床[1]。碲主要与黄铁矿、黄铜矿、闪锌矿等共生,含量仅 0.001%-0.1%;主要碲矿物有碲铅矿、碲铋矿、辉碲铋矿以及碲金矿、碲铜矿等。以上矿物很少见均无工业价值。 1993年,中国碲的工业储量1.3446万吨,当年产量为3.990吨。美国、加拿大、日本、秘鲁和斐济等国1979年产金属碲约290吨,大约消费 280吨。前苏联也是碲的重要生产国。中国辽宁、湖南、广东、台湾等地有工业规模的碲生产。1979年工业纯碲的价格为44.1-50.7美元/公斤。

 

碲 - 制取

硒和碲与硫的化学性质相近,它们均属典型的亲铜元素,因此硒和碲主要伴生在黄铜矿、斑铜矿、黄铁矿。硒和碲的生产主要取决于铜的生产状况,铜阳极泥是生产硒和碲的主要原料(一般含硒3%-28%,碲1.5%-10%)。

硒和碲的另一重要来源是铅或镍的阳极泥和有色金属冶炼的烟尘,硫酸生产中产出含硒、碲的酸泥分别波动在3%-52%和0.2%-14%。从这些原料中提取硒和碲主要包括富集和硒碲的制取和提纯两大环节,回收方法因原料不同而异,一般分为Seq和Teq制备。

铜 电解精炼所得的阳极泥是碲的主要来源。处理阳极泥的主要方法是硫酸化焙烧法。其他方法如苏打烧结法等应用较少。据阳极泥中碲含量的高低,采用不同的处理方 法:对含碲高的阳极泥,干燥后在250℃下进行硫酸化焙烧,然后在700℃使二氧化硒挥发,碲则留在焙烧渣中。对含碲低的铜阳极泥和铅电解阳极泥混合处理 时,可进行还原熔炼。对于高纯碲的制取主要采用电解法。

 

碲 - 用途

碲 主要用于冶金、电子工业、化学工业、玻璃等方面,约55%碲在冶金中用作合金添加剂增强钢、铜及铜合金、铅等的机械性能;化学工业中用碲作橡胶硫化过程 的加速剂、有机反应催化剂;玻璃陶瓷工业用碲作脱色剂、着色剂和制造特种光学玻璃;制药工业用谛作消毒剂、杀虫剂、灭菌剂和抗氧化剂。碲也用于复印机。碲 金属化合物是制造太阳能电池、辐射探测器和红外探测器的材料,用于夜视仪、地面资源勘探。碲热电转换器用于宇航动力系统的热发电机、微波装置、水底导弹特 殊冷却装置等方面。

在冶金工业中应用

碲在冶金工业中的用量约占碲的总消费量的80%以上。钢和铜合金加入少量碲,可增加钢 得延展性,能改善低碳钢、不锈钢和铜的 切削加工性能并增加硬度;在白口铸铁中碲被用作碳化物稳定剂,使表面坚固耐磨;含少量碲的铅,可提高材料的耐蚀性、耐磨性和强度,用作海底电缆的护套;铅 中加入碲能增加铅的硬度,用来制作电池极板和印刷铅字。碲可用作石油裂解催化剂的添加剂以及制取乙二醇的催化剂。氧化碲用作蓝、棕、红色玻璃的着色剂高纯 碲可作温差电材料的合金组分。高纯碲可用作温差电材料的合金组分,其中碲化铋为良好的制冷材料。碲和若干碲化物As32Te48Si20是制作电子计算机 存贮器的半导体材料。超纯碲单晶是新型的红外材料。高纯碲用量虽少,作用颇大。

引用出處: 

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Selenium ( /sɪˈliːniəm/ si-LEE-nee-əm) is a chemical element with the atomic number 34, represented by the chemical symbol Se, an atomic mass of 78.96. It is a nonmetal, chemically related to sulfur and tellurium, and rarely occurs in its elemental state in nature.

Isolated selenium occurs in several different forms, the most stable of which is a dense purplish-gray semi-metal (semiconductor) form that is, in terms of structure, a trigonal polymer chain. It conducts electricity better in the light than in the dark, and is used in photocells (see section Allotropes below). Selenium also exists in many non-conductive forms: a black glass-like allotrope, as well as several red crystalline forms built of eight-membered ring molecules, like its lighter cousin sulfur.

Selenium is found in economic quantities in sulfide ores such as pyrite, partially replacing the sulfur in the ore matrix. Minerals that are selenide or selenate compounds are also known, but are rare. The chief commercial uses for selenium today are in glassmaking and in chemicals and pigments. Uses in electronics, once important, have been supplanted by silicon semiconductor devices.

Selenium salts are toxic in large amounts, but trace amounts of the element are necessary for cellular function in most, if not all, animals, forming the active center of the enzymes glutathione peroxidase and thioredoxin reductase (which indirectly reduce certain oxidized molecules in animals and some plants) and three known deiodinase enzymes (which convert one thyroid hormone to another). Selenium requirements in plants differ by species, with some plants, it seems, requiring none.[3]

 

 

Contents

[hide]

  • 1 History and global demand
  • 2 Occurrence
  • 3 Production and allotropic forms
  • 4 Isotopes
  • 5 Health effects and nutrition
    • 5.1 Indicator plants
    • 5.2 Toxicity
    • 5.3 Deficiency
    • 5.4 Controversial health effects
  • 6 Non-biologic applications
  • 7 Biologic applications
    • 7.1 Detection in biological fluids
  • 8 Evolution in biology
  • 9 Chemistry
    • 9.1 Chalcogen compounds
    • 9.2 Halogen compounds
    • 9.3 Selenides
    • 9.4 Other compounds
  • 10 See also
  • 11 References
  • 12 External links

[edit] History and global demand

Selenium (Greek σελήνη selene meaning "Moon") was discovered in 1817 by Jöns Jakob Berzelius,[4] who found the element associated with tellurium (named for the Earth). It was discovered as a byproduct of sulfuric acid production.

It came to medical notice later because of its toxicity to humans working in industry. It was also recognized as an important veterinary toxin, seen in animals eating high-selenium plants. In 1954, the first hints of specific biological functions of selenium were discovered in microorganisms. Its essentiality for mammalian life was discovered in 1957. In the 1970s, it was shown to be present in two independent sets of enzymes. This was followed by the discovery of selenocysteine in proteins. During the 1980s, it was shown that selenocysteine is encoded by the codon TGA. The recoding mechanism was worked out first in bacteria and then in mammals (see SECIS element).

In industry, growth in selenium consumption has been driven by steady development of new uses, including applications in rubber compounding, steel alloying, and selenium rectifiers. Selenium is also an essential material in the drums of laser printers and copiers. By 1970, selenium in rectifiers had largely been replaced by silicon, but its use as a photoconductor in plain-paper copiers had become its leading application. During the 1980s, the photoconductor application declined (although it was still a large end-use) as more and more copiers using organic photoconductors were produced. At the current time, the largest use of selenium worldwide is in glass manufacturing, followed by uses in chemicals and pigments. Electronics use, despite a number of continued applications, continues to decline.[5]

In the late 1990s, the use of selenium (usually with bismuth) as an additive to plumbing brasses to meet no-lead environmental standards became important. At present, total world selenium production continues to increase modestly.

[edit] Occurrence

 

 

 

 

Native selenium

See also: Category:Selenide minerals

Selenium occurs naturally in a number of inorganic forms, including selenide, selenate, and selenite. In soils, selenium most often occurs in soluble forms such as selenate (analogous to sulfate), which are leached into rivers very easily by runoff.

Selenium has a biological role, and it is found in organic compounds such as dimethyl selenide, selenomethionine, selenocysteine, and methylselenocysteine. In these compounds, selenium plays a role analogous to that of sulfur.

Selenium is most commonly produced from selenide in many sulfide ores, such as those of copper, silver, or lead. It is obtained as a byproduct of the processing of these ores, from the anode mud of copper refineries and the mud from the lead chambers of sulfuric acid plants. These muds can be processed by a number of means to obtain free selenium.

Natural sources of selenium include certain selenium-rich soils, and selenium that has been bioconcentrated by certain plants. Anthropogenic sources of selenium include coal burning and the mining and smelting of sulfide ores.[6]

[edit] Production and allotropic forms

 

 

 

 

Structure of trigonal selenium

Native selenium is a rare mineral, which does not usually form good crystals, but, when it does, they are steep rhombohedrons or tiny acicular (hair-like) crystals.[7] Isolation of selenium is often complicated by the presence of other compounds and elements.

Most elemental selenium comes as a byproduct of refining copper or producing sulfuric acid.[8][9]

Industrial production of selenium often involves the extraction of selenium dioxide from residues obtained during the purification of copper. Common production begins by oxidation with sodium carbonate to produce selenium dioxide. The selenium dioxide is then mixed with water and the solution is acidified to form selenous acid (oxidation step). Selenous acid is bubbled with sulfur dioxide (reduction step) to give elemental selenium.

Elemental selenium produced in chemical reactions invariably appears as the amorphous red form: an insoluble, brick-red powder. When this form is rapidly melted, it forms the black, vitreous form, which is usually sold industrially as beads. The most thermodynamically stable and densest form of selenium is the electrically conductive gray (trigonal) form, which is composed of long helical chains of selenium atoms (see figure).[10] The conductivity of this form is notably light-sensitive. Selenium also exists in three different deep-red crystalline monoclinic forms, which are composed of Se8 molecules, similar to many allotropes of sulfur.[11][12] However, selenium does not exhibit the unusual changes in viscosity that sulfur undergoes when gradually heated.[12][13]

[edit] Isotopes

Main article: Isotopes of selenium

Selenium has six naturally occurring isotopes, five of which are stable: 74Se, 76Se, 77Se, 78Se, and 80Se. The last three also occur as fission products, along with 79Se, which has a half-life of 327,000 years.[14][15] The final naturally occurring isotope, 82Se, has a very long half-life (~1020 yr, decaying via double beta decay to 82Kr), which, for practical purposes, can be considered to be stable. Twenty-three other unstable isotopes have been characterized.

See also Selenium-79 for more information on recent changes in the measured half-life of this long-lived fission product, important for the dose calculations performed in the frame of the geological disposal of long-lived radioactive waste.

[edit] Health effects and nutrition

 

NFPA 704

 

 

 

0

2

0

Fire diamond for elemental selenium

Although it is toxic in large doses, selenium is an essential micronutrient for animals. In plants, it occurs as a bystander mineral, sometimes in toxic proportions in forage (some plants may accumulate selenium as a defense against being eaten by animals, but other plants such as locoweed require selenium, and their growth indicates the presence of selenium in soil).[3] See more on plant nutrition below.

Selenium is a component of the unusual amino acids selenocysteine and selenomethionine. In humans, selenium is a trace element nutrient that functions as cofactor for reduction of antioxidant enzymes, such as glutathione peroxidases[16] and certain forms of thioredoxin reductase found in animals and some plants (this enzyme occurs in all living organisms, but not all forms of it in plants require selenium).

The glutathione peroxidase family of enzymes (GSH-Px) catalyze certain reactions that remove reactive oxygen species such as hydrogen peroxide and organic hydroperoxides:

 

2 GSH + H2O2----GSH-Px → GSSG + 2 H2O

Selenium also plays a role in the functioning of the thyroid gland and in every cell that uses thyroid hormone, by participating as a cofactor for the three known thyroid hormone deiodinases, which activate and then deactivate various thyroid hormones and their metabolites.[17] It may inhibit Hashimotos's disease, in which the body's own thyroid cells are attacked as alien. A reduction of 21% on TPO antibodies was reported with the dietary intake of 0.2 mg of selenium.[18]

Dietary selenium comes from nuts, cereals, meat, mushrooms, fish, and eggs. Brazil nuts are the richest ordinary dietary source (though this is soil-dependent, since the Brazil nut does not require high levels of the element for its own needs). In descending order of concentration, high levels are also found in kidney, tuna, crab, and lobster.[19][20]

The human body's content of selenium is believed to be in the 13-20 milligram range.[21]

[edit] Indicator plants

Certain species of plants are considered indicators of high selenium content of the soil, since they require high levels of selenium to thrive. The main selenium indicator plants are Astragalus species (including some locoweeds), prince's plume (Stanleya sp.), woody asters (Xylorhiza sp.), and false goldenweed (Oonopsis sp.)[22]

[edit] Toxicity

Although selenium is an essential trace element, it is toxic if taken in excess. Exceeding the Tolerable Upper Intake Level of 400 micrograms per day can lead to selenosis.[23] This 400 microgram (µg) Tolerable Upper Intake Level is based primarily on a 1986 study of five Chinese patients who exhibited overt signs of selenosis and a follow up study on the same five people in 1992.[24] The 1992 study actually found the maximum safe dietary Se intake to be approximately 800 micrograms per day (15 micrograms per kilogram body weight), but suggested 400 micrograms per day to not only avoid toxicity, but also to avoid creating an imbalance of nutrients in the diet and to account for data from other countries.[25] The Chinese people who suffered from selenium toxicity ingested selenium by eating corn grown in extremely selenium-rich stony coal (carbonaceous shale). This coal was shown to have selenium content as high as 9.1%, the highest concentration in coal ever recorded in literature.[26] A dose of selenium as small as 5 milligram (5000 µg) per day can be lethal for many humans.[27]

 

 

 

 

 

Reference ranges for blood tests, showing selenium in purple in center

Symptoms of selenosis include a garlic odor on the breath, gastrointestinal disorders, hair loss, sloughing of nails, fatigue, irritability, and neurological damage. Extreme cases of selenosis can result in cirrhosis of the liver, pulmonary edema, and death.[28] Elemental selenium and most metallic selenides have relatively low toxicities because of their low bioavailability. By contrast, selenates and selenites are very toxic, having an oxidant mode of action similar to that of arsenic trioxide. The chronic toxic dose of selenite for humans is about 2400 to 3000 micrograms of selenium per day for a long time.[29] Hydrogen selenide is an extremely toxic, corrosive gas.[30] Selenium also occurs in organic compounds, such as dimethyl selenide, selenomethionine, selenocysteine and methylselenocysteine, all of which have high bioavailability and are toxic in large doses. Nano-size selenium has equal efficacy, but much lower toxicity.[31]

On 19 April 2009, twenty-one polo ponies began to die shortly before a match in the United States Polo Open. Three days later, a pharmacy released a statement explaining that the horses had received an incorrect dose of one of the ingredients used in a vitamin/mineral supplement compound, with which the horses had been injected. Such nutrient injections are common to promote recovery after a match, but this mixture had been compounded by a compounding pharmacy not familiar with it. Analysis of blood levels of inorganic compounds in the supplement indicated the selenium concentrations were ten to fifteen times higher than normal in the horses' blood samples, and 15 to 20 times higher than normal in their liver samples. It was later confirmed that selenium was the ingredient in question.[32] Selenium is active in only tiny amounts, and has a history of causing accidental poisonings in supplements when the dose that is supposed to be in micrograms is given by mistake in milligrams (1000 times as much).

Selenium poisoning of water systems may result whenever new agricultural runoff courses through normally dry, undeveloped lands. This process leaches natural soluble selenium compounds (such as selenates) into the water, which may then be concentrated in new "wetlands" as the water evaporates. High selenium levels produced in this fashion have been found to have caused certain congenital disorders in wetland birds.[33]

[edit] Deficiency

Main article: selenium deficiency

Selenium deficiency is rare in healthy, well-nourished individuals. It can occur in patients with severely compromised intestinal function, those undergoing total parenteral nutrition, and[34] on advanced-aged people (over 90). Also, people dependent on food grown from selenium-deficient soil are at risk. Although New Zealand has low levels of selenium in its soil, adverse health effects have not been detected.[35]

Selenium deficiency may only occur when a low selenium status is linked with an additional stress, such as chemical exposure or increased oxidant stress due to vitamin E deficiency.[36]

There are interactions between selenium and other nutrients, such as iodine and vitamin E. The interaction is observed in the etiology of many deficiency diseases in animals, and pure selenium deficiency is, in fact, rare. The effect of selenium deficiency on health remains uncertain, in particular, in relation to Kashin-Beck disease.[37]

[edit] Controversial health effects

 

Cancer

Several studies have suggested a possible link between cancer and selenium deficiency.[38][39][40][41] One study, known as the NPC, was conducted to test the effect of selenium supplementation on the recurrence of skin cancers on selenium-deficient men. It did not demonstrate a reduced rate of recurrence of skin cancers, but did show a reduced occurrence of total cancers, although without a statistically significant change in overall mortality.[42] The preventative effect observed in the NPC was greatest in those with the lowest baseline selenium levels.[43] In 2009, the 5.5 year SELECT study reported selenium and vitamin E supplementation, both alone and together, did not significantly reduce the incidence of prostate cancer in 35,000 men who "generally were replete in selenium at baseline".[43] The SELECT trial reported vitamin E did not reduce prostate cancer as it had in the alpha-tocopherol, beta carotene (ATBC) study, but the ATBC had a large percentage of smokers, while the SELECT trial did not.[43] There was a slight trend toward more prostate cancer in the SELECT trial, but in the vitamin E only arm of the trial, where no selenium was given.

Dietary selenium prevents chemically-induced carcinogenesis in many rodent studies.[44] It has been proposed that selenium may help prevent cancer by acting as an antioxidant or by enhancing immune activity. Not all studies agree on the cancer-fighting effects of selenium. One study of naturally occurring levels of selenium in over 60,000 participants did not show a significant correlation between those levels and cancer.[45] The SU.VI.MAX study[46] concluded low-dose supplementation (with 120 mg of ascorbic acid, 30 mg of vitamin E, 6 mg of beta carotene, 100 µg of selenium, and 20 mg of zinc) resulted in a 30% reduction in the incidence of cancer and a 37% reduction in all-cause mortality in males, but did not get a significant result for females.[47] However, there is evidence selenium can help chemotherapy treatment by enhancing the efficacy of the treatment, reducing the toxicity of chemotherapeutic drugs, and preventing the body's resistance to the drugs.[48] Studies of cancer cells in vitro showed that chemotherapeutic drugs, such as taxol and Adriamycin, were more toxic to strains of cancer cells when selenium was added.[49][50]

In March 2009, vitamin E (400 IU) and selenium (200 micrograms) supplements were reported to affect gene expression and can act as a tumor suppressor.[51] Eric Klein, MD from the Glickman Urological and Kidney Institute in Ohio said the new study “lend[s] credence to the previous evidence that selenium and vitamin E might be active as cancer preventatives”.[52] In an attempt to rationalize the differences between epidemiological and in vitro studies and randomized trials like SELECT, Klein said randomized controlled trials “do not always validate what we believe biology indicates and that our model systems are imperfect measures of clinical outcomes in the real world”.[52]

 

HIV/AIDS

Some research has indicated a geographical link between regions of selenium-deficient soils and peak incidences of HIV/AIDS infection. For example, much of sub-Saharan Africa is low in selenium. However, Senegal is not, and also has a significantly lower level of AIDS infection than the rest of the continent. AIDS appears to involve a slow and progressive decline in levels of selenium in the body. Whether this decline in selenium levels is a direct result of the replication of HIV[53] or related more generally to the overall malabsorption of nutrients by AIDS patients remains debated.

Low selenium levels in AIDS patients have been directly correlated with decreased immune cell count and increased disease progression and risk of death.[54] Selenium normally acts as an antioxidant, so low levels of it may increase oxidative stress on the immune system, leading to its more rapid decline. Others have argued T-cell-associated genes encode selenoproteins similar to human glutathione peroxidase. Depleted selenium levels in turn lead to a decline in CD4 helper T-cells, further weakening the immune system.[55]

Regardless of the cause of depleted selenium levels in AIDS patients, studies have shown selenium deficiency does strongly correlate with the progression of the disease and the risk of death.[56][57][58]

 

Tuberculosis

Some research has suggested selenium supplementation, along with other nutrients, can help prevent the recurrence of tuberculosis.[59]

 

Diabetes

A well-controlled study showed selenium intake is positively correlated with the risk of developing type 2 diabetes. Because high serum selenium levels are positively associated with the prevalence of diabetes, and because selenium deficiency is rare, supplementation is not recommended in well-nourished populations, such as the U.S.[60] More recent studies, however, have indicated selenium may help inhibit the development of type 2 diabetes in men, though the mechanism for the possible preventative effect is not known.[61]

 

Mercury

Experimental findings have demonstrated a protective effect of selenium on methylmercury toxicity, but epidemiological studies have been inconclusive in linking selenium to protection against the adverse effects of methylmercury.[62]

[edit] Non-biologic applications

 

Chemistry

Selenium is a catalyst in many chemical reactions and is widely used in various industrial and laboratory syntheses, especially organoselenium chemistry. It is also widely used in structure determination of proteins and nucleic acids by X-ray crystallography (incorporation of one or more Se atoms helps with MAD and SAD phasing.)

 

Manufacturing and materials use

The largest use of selenium worldwide is in glass and ceramic manufacturing, where it is used to give a red color to glasses, enamels and glazes as well as to remove color from glass by counteracting the green tint imparted by ferrous impurities.

Selenium is used with bismuth in brasses to replace more toxic lead. It is also used to improve abrasion resistance in vulcanized rubbers.

 

Electronics

Because of its photovoltaic and photoconductive properties, selenium is used in photocopying, photocells, light meters and solar cells. It was once widely used in rectifiers. These uses have mostly been replaced by silicon-based devices, or are in the process of being replaced. The most notable exception is in power DC surge protection, where the superior energy capabilities of selenium suppressors make them more desirable than metal oxide varistors.

Sheets of amorphous selenium convert x-ray images to patterns of charge in xeroradiography and in solid-state, flat-panel x-ray cameras.

 

Photography

Selenium is used in the toning of photographic prints, and it is sold as a toner by numerous photographic manufacturers including Kodak and Fotospeed. Its use intensifies and extends the tonal range of black and white photographic images as well as improving the permanence of prints.

Early photographic light meters used selenium but this application is now obsolete.

[edit] Biologic applications

 

Medical use

The substance loosely called selenium sulfide (approximate formula SeS2) is the active ingredient in some anti-dandruff shampoos.[63] The selenium compound kills the scalp fungus Malassezia, which causes shedding of dry skin fragments. The ingredient is also used in body lotions to treat Tinea versicolor due to infection by a different species of Malassezia fungus.[64]

 

Nutrition

Selenium is used widely in vitamin preparations and other dietary supplements, in small doses (typically 50 to 200 micrograms per day for adult humans). Some livestock feeds are fortified with selenium as well.

[edit] Detection in biological fluids

Selenium may be measured in blood, plasma, serum or urine to monitor excessive environmental or occupational exposure, confirm a diagnosis of poisoning in hospitalized victims or to assist in a forensic investigation in a case of fatal overdosage. Some analytical techniques are capable of distinguishing organic from inorganic forms of the element. Both organic and inorganic forms of selenium are largely converted to monosaccharide conjugates (selenosugars) in the body prior to being eliminated in the urine. Cancer patients receiving daily oral doses of selenothionine may achieve very high plasma and urine selenium concentrations.[65]

[edit] Evolution in biology

Main article: Evolution of dietary antioxidants

Over three billion years ago, blue-green algae were the most primitive oxygenic photosynthetic organisms and are ancestors of multicellular eukaryotic algae.[66] Algae that contain the highest amount of antioxidant selenium, iodide, and peroxidase enzymes were the first living cells to produce poisonous oxygen in the atmosphere. It has been suggested that algal cells required a protective antioxidant action, in which selenium and iodides, through peroxidase enzymes, have had this specific role.[66][67] Selenium, which acts synergistically with iodine,[68] is a primitive mineral antioxidant, greatly present in the sea and prokaryotic cells, where it is an essential component of the family of glutathione peroxidase (GSH-Px) antioxidant enzymes; seaweeds accumulate high quantity of selenium and iodine.[66] In 2008, a study showed that iodide also scavenges reactive oxygen species (ROS) in algae, and that its biological role is that of an inorganic antioxidant, the first to be described in a living system, active also in an in vitro assay with the blood cells of today’s humans."[69]

From about three billion years ago, prokaryotic selenoprotein families drive selenocysteine evolution. Selenium is incorporated into several prokaryotic selenoprotein families in bacteria, archaea and eukaryotes as selenocysteine,[70] where selenoprotein peroxiredoxins protect bacterial and eukaryotic cells against oxidative damage. Selenoprotein families of GSH-Px and the deiodinases of eukaryotic cells seem to have a bacterial phylogenetic origin. The selenocysteine-containing form occurs in species as diverse as green algae, diatoms, sea urchin, fish and chicken. Selenium enzymes are involved in utilization of the small reducing molecules glutathione and thioredoxin. One family of selenium-containing molecules (the glutathione peroxidases) destroy peroxide and repair damaged peroxidized cell membranes, using glutathione. Another selenium-containing enzyme in some plants and in animals (thioredoxin reductase) generates reduced thioredoxin, a dithiol that serves as an electron source for peroxidases and also the important reducing enzyme ribonucleotide reductase that makes DNA presursors from RNA precursors.[71]

At about 500 Mya, plants and animals began to transfer from the sea to rivers and land, the environmental deficiency of marine mineral antioxidants (as selenium, iodine, etc.) was a challenge to the evolution of terrestrial life.[66] Trace elements involved in GSH-Px and superoxide dismutase enzymes activities, i.e. selenium, vanadium, magnesium, copper, and zinc, may have been lacking in some terrestrial mineral-deficient areas.[70] Marine organisms retained and sometimes expanded their seleno-proteomes, whereas the seleno-proteomes of some terrestrial organisms were reduced or completely lost. These findings suggest that, with the exception of vertebrates, aquatic life supports selenium utilization, whereas terrestrial habitats lead to reduced use of this trace element.[72] Marine fishes and vertebrate thyroid glands have the highest concentration of selenium and iodine. From about 500 Mya, freshwater and terrestrial plants slowly optimized the production of “new” endogenous antioxidants such as ascorbic acid (Vitamin C), polyphenols (including flavonoids), tocopherols, etc. A few of these appeared more recently, in the last 50–200 million years, in fruits and flowers of angiosperm plants. In fact, the angiosperms (the dominant type of plant today) and most of their antioxidant pigments evolved during the late Jurassic period.

The deiodinase isoenzymes constitute another family of eukaryotic selenoproteins with identified enzyme function. Deiodinases are able to extract electrons from iodides, and iodides from iodothyronines. They are, thus, involved in thyroid-hormone regulation, participating in the protection of thyrocytes from damage by H2O2 produced for thyroid-hormone biosynthesis.[66][67] About 200 Mya, new selenoproteins were developed as mammalian GSH-Px enzymes.[73][74][75][76]

[edit] Chemistry

See also: Category:Selenium compounds and organoselenium chemistry

[edit] Chalcogen compounds

Selenium forms two oxides: selenium dioxide (SeO2) and selenium trioxide (SeO3). Selenium dioxide is formed by the reaction of elemental selenium with oxygen:[12]

 

Se8 + 8 O2 → 8 SeO2

It is a polymeric solid that forms monomeric SeO2 molecules in the gas phase. It dissolves in water to form selenous acid, H2SeO3. Selenous acid can also be made directly by oxidising elemental selenium with nitric acid:[77]

 

3 Se + 4 HNO3 → 3 H2SeO3 + 4 NO

Salts of selenous acid are called selenites. These include silver selenite (Ag2SeO3) and sodium selenite (Na2SeO3).

Hydrogen sulfide reacts with aqueous selenous acid to produce selenium disulfide:

 

H2SeO3 + 2 H2S → SeS2 + 3 H2O

Selenium disulfide consists of 8-membered rings of sulfur atoms with selenium replacing some of the sulfur atoms. It has an approximate composition of SeS2, with individual rings varying in composition, such as Se4S4 and Se2S6. It has various applications, including use in shampoo as an anti-dandruff agent, an inhibitor in polymer chemistry, a glass dye, and a reducing agent in fireworks.[77]

Unlike sulfur, which forms a stable trioxide, selenium trioxide is unstable and decomposes to the dioxide above 185 °C:[12][77]

 

2 SeO3 → 2 SeO2 + O2 (ΔH = −54 kJ/mol)

Selenium trioxide may be synthesized by dehydrating selenic acid, H2SeO4, which is itself produced by the oxidation of selenium dioxide with hydrogen peroxide:[78]

 

SeO2 + H2O2 → H2SeO4

Hot, concentrated selenic acid is capable of dissolving gold, forming gold(III) selenate.[79]

[edit] Halogen compounds

Selenium reacts with fluorine to form selenium hexafluoride:

 

Se8 + 24 F2 → 8 SeF6

Unlike its sulfur counterpart (sulfur hexafluoride) however, SeF6 is more reactive and is a toxic pulmonary irritant.[80] It can cause frostbite and severe irritation on contact with skin.[81]

Other selenium halides include SeF4, Se2Cl2, SeCl4, and Se2Br2. Selenium dichloride (SeCl2), an important reagent in the study of selenium chemistry, may be prepared in pure form by reacting elemental selenium with SO2Cl2 in THF solution.[82] Some of the selenium oxyhalides, such as SeOF2, are useful as nonaqueous solvents.[12]

[edit] Selenides

Like oxygen and sulfur, selenium forms selenides with metals. For example, reaction with aluminum forms aluminum selenide:[12]

 

3 Se8 + 16 Al → 8 Al2Se3

Other selenides include mercury selenide (HgSe), lead selenide (PbSe), and zinc selenide (ZnSe). An important selenide is copper indium gallium diselenide (Cu(Ga,In)Se2), a semiconductor.

Selenium does not react directly with hydrogen; so hydrogen selenide, the analogue of hydrogen sulfide and water, is prepared by first reacting selenium with a metal to produce a selenide, and then protonating the selenide anion with an acid to produce H2Se.[12]

[edit] Other compounds

Tetraselenium tetranitride, Se4N4, is an explosive orange compound analogous to S4N4.[12][83][84] It can be synthesized by the reaction of SeCl4 with [((CH3)3Si)2N]2Se in dichloromethane solution at −78 °C.[85]

Selenium reacts with cyanides to yield selenocyanates.[12] For example:

 

8 KCN + Se8 → 8 KSeCN

[edit] See also

引用出處: 

 http://en.wikipedia.org/wiki/Selenium

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硒:符 号:Se,英文名称:Selenium,非金属元素,是有灰色单质金属光泽的固体,声音在其中的传播速率:(m/S):3350,密度:4.81克/厘 米³,熔点:217℃,沸点: 684.9℃,硒与它的同族元素硫相比,在地壳中的含量少得多。硒成单质存在的矿是极难找到的。硒是从燃烧黄铁矿以制取硫酸的铅室中发现的,是贝齐里乌斯 发现铈、钍后发现的又一个化学元素。他命名这种新元素为selenium。他还发现到硒的同素异形体。

纠错 编辑摘要

目录

  • 1 概述
  • 2 发现
  • 3 主要用途
  • 4 综合性质
  • 5 发现及来源
  •  

  • 1 概述
    • 1.1 简介
  • 2 发现
  • 3 主要用途
  • 4 综合性质
  • 5 发现及来源
  • 6 辅助资料
  • 7 自然硒
  • 8 硒资源
  • 9 硒污染
  • 10 硒化物
  • 11 对人体的影响
    • 11.1 含量与分布
    • 11.2 食物来源
    • 11.3 建议量
    • 11.4 吸收
    • 11.5 运输
    • 11.6 代谢
    • 11.7 生化功能
    • 11.8 缺乏与毒性
    • 11.9 与其他营养素的关系
  • 12 参考资料

 

 

硒 - 概述

 

硒单质

简介

硒 是一种化学元素,它的化学符号是Se,它的原子序数是34,硒是稀散元素之一,在已知的六种固体同素异形体中,三种晶体(α单斜体、β单斜体,和灰色三角 晶)是最重要的。也以三种非晶态固体形式存在;红色和黑色的两种无定形玻璃状的硒。前者性脆,密度4.26克/厘米3;后者密度4.28克/厘米3。第一 电离能为9.752电子伏特。硒在空气中燃烧发出蓝色火焰,生成二氧化硒(SeO2)。也能直接与各种金属和非金属反应,包括氢和卤素。不能与非氧化性的 酸作用,但它溶于浓硫酸、硝酸和强碱中。溶于水的硒化氢能使许多重金属离子沉淀成为微粒的硒化物。硒与氧化态为+1的金属可生成两种硒化物,即正硒化物 (M2Se)和酸式硒化物(MHSe)。正的碱金属和碱土金属硒化物的水溶液会使元素硒溶解,生成多硒化合物(M2Sen),与硫能形成多硫化物相似。

元素来源 可从电解铜的阳极泥和硫酸厂的烟道灰、酸泥等废料中回收而得。

命 名由来 硒之英文全名为Selenium,取自希腊文Σελήνη(月亮女神塞勒涅的名字),为月亮之意。因为它是一种固体非金属,故此用石字部首,并赋 予西字音译。 硒对生物同时具有必需性和毒性. 性质与硫及碲相似。它在有光时,导电性能较黑暗时好,故用来做光电池。

 

硒 - 发现

 

永斯·雅各布·贝齐里乌斯

发现人:永斯·雅各布·贝齐里乌斯(Jöns Jakob Berzelius) 

发现年代:1817年

发现过程:

1817年,瑞典的贝采利乌斯从硫酸厂的铅室底部的粘物质中制得硒。

 

 

硒 - 主要用途

 

硒锭

1.光敏材料

如: 干印术的光复制,这是利用无定形硒的薄漠对于光的敏感性,能使含有铁化合物的有色玻璃退色。也用作油漆、搪瓷、玻璃和墨水中的颜色、塑料。还用于 制作光电池、整流器、光学仪器、光度计等。硒在电子工业中可用作光电管、太阳能电池,在电视和无线电传真等方面也使用硒。硒能使玻璃着色或脱色,高质量的 信号用透镜玻璃中含2%硒,含硒的平板玻璃用作太阳能的热传输板和激光器窗口红外过滤器。

2.电解锰行业催化剂

冶金方面, 电解锰行业的硒用量占到中国全部硒产量的较大比重,此外,含硒的碳素钢、不锈钢和铜合金具有良好的加工性能,可高速切削,加工的零件表面光 洁;硒与其他元素组成的合金用以制造低压整流器、光电池、热电材料。硒以化合物形式用作有机合成氧化剂、催化剂,可在石油工业上应用。硒加入橡胶中可增强 其耐磨性。硒与硒化合物加入润滑脂。

3.营养元素

由于硒是动物和人体中一些抗氧化酶(谷胱甘肽过氧化物酶)和硒-P蛋白的 重要组成部分,在体内起着平衡氧化还原氛围的作用,研究证明具有提高动物免疫 力作用,在国际上硒对于免疫力影响和癌症预防的研究是该领域的热点问题,因此,硒可作为动物饲料微量添加剂,也在植物肥料中添加微量元素肥,提高农副产品 含硒量。硒已被作为人体必需的微量元素,目前,中国营养学会推荐的成人摄入量为每日50-250微克,而我国2/3地区硒摄入量低于最低推荐值,因此,中 国是一个既有丰富硒资源,又存在大面积硒缺乏地区,这也是国际学者对中国感兴趣的原因。

 

硒 - 综合性质

 

元素符号:Se

元素英文名称:Selenium

元素类型:非金属元素

原子体积:(立方厘米/摩尔):16.45

元素在海水中的含量:(ppm):太平洋表面  0.000000015

地壳中含量:(ppm):0.05

相对原子质量:78.84

原子序数:34

 

氧化态:Main  Se+4, Se+6

Other  Se-2, Se+1, Se+2

化学键能:(kJ /mol)

硒粒

Se-H  305

Se-C  245

Se-O  343

Se-F  285

Se-Cl  245

Se-Se  330

 

晶胞参数:

a = 905.4 pm

b = 908.3 pm

c = 1160.1 pm

α = 90°

β = 90.810°

γ = 90°

 

质子数:34

中子数:45

摩尔质量:79

原子半径:1.22

所属周期:4

所属族数:VIA

电子层排布:2-8-18-6

晶体结构:晶胞为六方晶胞。

 

电离能 (kJ/ mol) 

M - M+ 940.9

M+ - M2+ 2044

M2+ - M3+ 2974

M3+ - M4+ 4144

M4+ - M5+ 6590

M5+ - M6+ 7883

M6+ - M7+ 14990

M7+ - M8+ 19500

M8+ - M9+ 23300

M9+ - M10+ 27200

莫氏硬度:2  

常见化合价:+4、+6

同位素:Se-74 Se-76 Se-77 Se-78 *Se-80 Se-82

 

硒 - 发现及来源

 

发现人:贝齐里乌斯(J.J.Bergelius)    发现年代:1817年

发现过程:1817年,瑞典的贝采利乌斯从硫酸厂的铅室底部的粘物质中制得硒。

元素来源:可从电解铜的阳极泥和硫酸厂的烟道灰、酸泥等废料中回收而得。

元素用途:硒的主要用途为干印术的光复制,这是利用无定形硒的薄漠对于光的敏感性,能使含有铁化合物的有色玻璃退色。也用作油漆、搪瓷、玻璃和墨水中的颜色、塑料。还用于制作光电池、整流器、光学仪器、光度计等。

 

硒 - 辅助资料

硒 与它的同族元素硫相比,在地壳中的含量少得多。硒成单质存在的矿是极难找到的。硒是从燃烧黄铁矿以制取硫酸的铅室中发现的,是贝齐里乌斯发现铈、钍后发现 的又一个化学元素。他命名这种新元素为selenium。他还发现到硒的同素异形体。他还原硒的氧化物,得到橙色无定形硒;缓慢冷却熔融的硒,得到灰色晶 体硒;在空气中让硒化物自然分解,得到黑色晶体硒。

 

硒 - 自然硒

 

名字来源:来源于希腊语Selene,意思是月之女神;

化学组成:主要成份是硒,含有微量的硫;

类别:自然元素-半金属元素-自然硒族;

晶系和空间群:三方晶系,P3221;

晶胞参数:a = 0.4366nm,c = 0.4954nm;

形态:为粒状或浸染状分布于基

硒粉

质中;

颜色:灰,灰紫色或微红色;

条痕:红色;

透明度:不透明;

光泽:亚金属光泽;

硬度:2;

解理和断口:(0112)完全解理;

比重:4.81 g/cm3;g/cm3

其他性质:晶体易弯曲,具有挠性;

成因和产状:自然硒为硒化物的风化产物,常由硒铅矿变来,与褐铁矿共生并被其胶结。

主要用途:硒的最显著性质是它的光电效应,由此它可作光电池,用于电视方面;还可用于玻璃工业、橡胶工业等部门,玻璃中加入硒可消除铁杂质引起的绿色,再橡胶配料中加入硒,能提供橡胶的抗热、抗氧化及耐磨性;

著名产地:玻利维亚Potosí,意大利Liguria,美国Nevada。

 

硒 - 硒资源

1817年瑞典科学家Berzelius发现了与元素碲性质相似的一种新元素,参照碲(原意为地球)的命名,给该元素取名为硒即月亮的意思。此后科学家们进行了大量的研究,特别是近20年更是

硒粒

有 了突破性的进展。硒对人类有着十分重要的作用,世界上有众多的低硒、缺硒地区。湖北省恩 施州有着世界上稀少的独立硒矿床和中国第一个高硒区。恩施市硒资源具有分布广、储量大、埋藏浅等特点。硒矿主要赋存于二迭系茅口组二段(硅质岩段)地层 中,主要分布在沐抚—板桥、罗针田—马者—铁厂坝、向家村—奇羊坝、中间河—黄村—沙地花被、双河—红土溪—石窑、芭蕉乡—盛家等地。硒矿储量达50多亿 吨,含硒品位为230—6300克/吨。双河渔塘坝(前坪背斜与太山庙背斜之间双河向斜南西段)拥有世界上唯一的独立硒矿床, 已探明储量64万吨,纯硒平均含量3637.5ppm,改写了“硒不能形成独立工业矿床”的传统结论。全市含硒碳质页岩和石煤出露面积为850平方公里, 矿层厚度3.6—9米,硒矿储量达50多亿吨,每吨含硒500—5500克,最高达84公斤,土壤硒最高178.8ppm,平均19.11ppm。以硒矿 床为中心的乡镇均为高硒区,占全市总面积的73%。

硒资源的利用:“抗癌之王”、增强免疫力、防止糖尿病、防止白内障、防止克山病、大骨节病、关节炎、解毒、排毒。

 

硒 - 硒污染

硒 污染,pollution by selenium,硒在地壳中的平均丰度约为 0.05ppm。硒是亲硫元素,在铜、铅、锌等硫化物矿床中往往有硒共生。硒是人和动物以 及部分植物必需的微量元素,一般富集在有机质内。黑页岩、煤和石油含有较多的硒。在黑页岩中,含硫量如低于0.5%,硒少于0.5ppm;含硫量如高于 1%,含硒量平均值为10ppm。根据日本和美国的调查,煤的含硒量为0.46~10.65ppm;石油含硒量为1ppm左右,有时低于0.1ppm。硒 在电子工业中用来制造硒整流器;在玻璃工业中,用作退色剂和着色剂。

对大气的污染:金属硫化物矿石在空气中焙烧时,硒化物氧化为二氧化硒(SeO2),从烟道排入大气,在常温下变为固体,遇水则生成亚硒酸(H2SeO3),所以可用水洗

硒污染

涤 除去烟气中的硒。挥发性的烷基硒可从动植物体内散发出来。二甲基二硒是植物的挥发物,二甲基硒是微生物和动物的挥发物,但数量都很少。据美国环境保护局统 计,1969年美国各种工业向大气排放的硒约855吨,其中燃煤动力工业占42%,玻璃工业占23%,铜、锌和铅矿石焙烧工业占 6%。美国波士顿大气中含硒量平均为0.001 微克/米3。据美国10个城市统计,飘尘含硒量为0.05~10ppm。目前硒还不是大气中的重要污染物。

对水体的污染:天然水体中硒的分 布主要取决于浸蚀的岩石类 型和水的pH值。工业区和非工业区河流含硒量差别不大。pH值对河水含硒影响较大。例如在美国富硒铁的科罗拉多州,地表水pH值小于7时,含硒量几乎都低 于1微克/升;而在pH值为7.8~8.2时,由于亚硒酸盐可氧化为易溶于水的硒酸盐,水中含硒就高于1微克/升,甚至高达400微克/升。废水中有时有 亚硒酸根离子(SeO卲)存在,在酸性条件下亚硒酸根离子还原为细颗粒状的元素硒。颜料和染料废水中含有硒化镉(CdSe)等硒化物。负二价形式的金属硒 化物很难溶解。目前工业中用硒不多,水体的硒污染只是局部问题。

对土壤的污染:硒可在土壤中富集,并被农作物吸收。用含硒量大于0.05ppm的水灌溉农田,每公斤饲料作物的含硒量可达4~5毫克。美国南达科他州和怀俄明州是富硒铁的地区,一些牧场的饲料每公斤硒含量竟高达30毫克。

对 健康的危害:饲料中含硒过多,会引起牲畜慢性硒中毒,患碱质病,出现脱毛、蹄变形甚至脱落,并有贫血、关节强直等症状。在新西兰、澳大利亚、芬兰等国以及 中国的西北和东北的一些缺硒地区,饲料中硒含量少于0.04ppm,会使羊、牛、马和鸡发生白肌病。在妊娠到授乳期的母畜饲料中添加0.1ppm的亚硒酸 钠,可以防止牛犊和羊羔患白肌病。克山病流行地区的人口服小剂量亚硒酸钠,对克山病有较好的预防效果。

工厂车间中含硒的粉尘、烟雾和蒸汽, 会刺激人眼和呼吸系统,使人流泪、喷嚏、鼻腔充血、咳嗽等,严重时则会引起舌苔增厚,呼吸和出汗时有大蒜味,胃 肠功能紊乱等。动物实验表明,亚急性中毒会引起肺炎、肝肾功能退化。试验表明,硒可使老鼠发生肝癌。接触亚硒酸时,皮肤和粘膜会受到强烈刺激或发生炎症。 亚硒酸和亚硒酸盐能被皮肤吸收进入体内积累。氯化氧硒(SeOCl2)是剧烈的糜烂性毒剂,能造成皮肤三度烧伤。二甲基硒能使人患急性咽喉炎和肺炎。

环 境标准:中国、美国、苏联都 规定饮用水中硒含量不得超过0.01毫克/升。农业灌溉用水最大容许含硒量,中国规定为0.01毫克/升,美国规定为0.05毫克/升。对于车间空气中的 SeO2,中国规定的最高容许浓度为0.1毫克/米3,美国规定工作8小时的平均值不得超过0.2毫克/米3。目前世界各国都未规定硒的环境大气质量标 准。

 

硒 - 硒化物

 

酵母硒多糖胶囊

溶 于水的硒化氢能使许多重金属离子沉淀成为微粒的硒化物。硒与氧化态为+1的金属可 生成两种硒化物,即正硒化物(m2se)和酸式硒化物(mhse)。硒及硒化物是重要的半导体材料,具有优良的光电性能。硒化物对皮肤黏膜有强烈的刺激作 用,硒盐直接与皮肤接触时产生化学烧伤,可出现红斑、水疮、溃疡。接触氧化硒粉尘可引起接触性皮炎,二氧化硒引起皮肤剧痛和麻木,二氧化硒对皮肤刺激更 强,经皮肤吸收而发生全身中毒。

 

硒 - 对人体的影响

硒是人体必需的微量矿物质营养素[1],多以氧化态(Se2+、Se4+、和Se6+)存在,化学性质与硫相似,许多含硫氨基酸,如甲硫胺酸(Met)、半胱氨酸(Cys)、胱氨酸也可用硒取代硫。

硒 在动物组织中最常以甲硒胺酸(selenomethionine,简称SeMet)和硒半胱氨酸(selenocysteine,简称SeCys)的形 态存在,其中甲硒胺酸无法由人体合成,仅能由植物合成后经摄食再经消化代谢而获得,故食材动植物来源组成将决定硒在饮食中的形式,此外,人体中甲硒胺酸可 以取代甲硫胺酸;但硒半胱胺酸不能取代半胱胺酸。硒在生理上的功能除了抗氧化外,还调控了甲状腺的代谢和维他命C的氧化还原态,也曾被提出和抗癌相关的可 能性。在食材成分含量里,同种植物性食材含硒成分变化相当大,乃因各原植物生长地的土壤中硒的浓度不同,当地的动物也随之反映相应情形,因此硒营养缺乏或 过量情形常有地域性关系。

硒对生物同时具有必需性和毒性。

氧化硒离子和亚氧化硒离子的毒性非常强,甚至具有类似砷的毒性模式。氧化硒更是具剧毒和腐蚀性的气体。

然而,纯硒元素和金属硒化物的毒性相对上不大,而且有些为重要的微量元素之一。严重缺乏可引致克山症和溪山症。它们的病征有:心肌坏死、萎缩、软骨组织坏死。另外又与甲状腺肿、呆小症和习惯性流产有关。

含量与分布

人 体本身的硒总含量为15mg。男性体内的硒多集中在睾丸及前列腺输精管中,会随精液一起排出体外。人体与动物有二个硒储存库,一为身体蛋白质的甲硒胺酸 (SelenoMethionine,SeMet),它的储存量视饮食中SeMet量而定,其提供硒的量,取决于甲硫胺酸的转换率;二为肝脏酵素榖胱甘肽 过氧化酶( glutathione peroxidase,GPX)的硒。

食物来源

硒 存在于土壤中,而世界各地的土壤硒含量皆不相同,各地植物所含的硒浓度也因此不同。一般而言,食物中的瘦肉、柿子、蒜头、海产、葱、南瓜等含有多量的 硒。动物制品的硒含量(约0.4-1.5μg/g)比植物体高;一般植物谷类的硒含量范围可在<0.1μg/g─>0.8μg/g;在海洋生 物中,硒类的含量也比植物多,但由于鱼类(尤其是体内含汞的鱼类)会形成汞─硒复合体,造成对硒的生物利用性极低,故虽然硒在鱼类的含量多但对于鱼类本身 的利用性极低;至于肉类会提供0.1-0.4μg/g;乳制品的硒含量则为<0.3μg/g。

另外,全谷物和核果种子也是好的来源。在饮水中提供的硒摄取量十分有限,除非水流经含硒量高的土壤地区才可能有较高的含量。

植物中的硒是因硒取代硫而进入植物体,硒型态有甲硒胺酸、硒胺酸与其代谢产物等。动物生长需要硒,在摄食植物时获得甲硒胺酸。饮食中硒的形式取决于动植物食品的组合。

硒的食物来源[2]

食品名称/重量 硒(μg)

鲔鱼 / 3 oz 68

火腿(瘦肉)/ 3 oz 42

蛤蜊 / 3 oz 41

鲑鱼 / 3 oz 40

意大利蛋面 /1杯 35

沙朗牛排 / 3 oz 28

鸡胸肉 / 3 oz 20

Special K cereal 17

麸燕麦片 / 1杯 14

全麦面包 / 1片 10

燕麦糊 / 1/2杯 10

白面包 / 1片 9

葡萄干麦片 / 1杯 4

建议量

民众的实际硒摄取量会因地而异,美国平均每日81μg、加拿大每日113–220μg ,高于RDA。均饮食估计可提供约104-124 μg的硒。成人之上限摄取量(UL)订为400μg。

硒的建议量在1980年只能根据估计而得,称为Estimated safe and adequate dietary intake(ESADDI);2000年则根据需要量之科学研究而订定每日建议摄取量(RDA)。

过 去曾有关于台湾境内硒之饮食摄取量的研究[3],分析结果六日饮食的硒摄取范围在104~124μg(1.3~1.6μmol)/day,平均值为 112μg(1.4μmol)/day,加上台湾非低硒区域,且食品贸易进出口抹去食品在硒含量上的地域性限制,推测台湾境内应无硒营养缺乏的问题。

硒的营养来源:

有机型式:甲硒胺酸(selenomethione)、硒半胱胺酸(selenocysteine)

无机型式:硒酸盐(selenate)、亚硒酸盐(selenite )

影响硒营养需求量的因素[4]

1.生物吸收率:见“吸收”。

2. 性别:早期来自中国研究报告,当时硒缺乏现象比现在严重,在此情形显示产龄女性较易罹患克山病(Keshan disease);另外,过去20年报 告显示孩童不论男女有相同的比例罹患克山病;性别的影响必须在硒摄取量极低的情下才会显现,假设考虑女性有较高机率罹患克山病,硒对各年龄层的需求量将以 男性参考体重为基准。

硒之膳食建议摄取量 (RDA)

年龄 美国 (μg/day)[5] 台湾 (μg/day)[6]

0 个月~ AI=15 15

6个月~ AI=20 20

1岁~ 20 20

4岁~ 30 25

7岁~ 30 30

10岁~ 40 40

13岁~ 40 50

14岁~ 55 50

孕妇 60 60

哺乳 70 70

RDA(建议摄取量 Recommanded Dietary Allowances):美国原始的饮食标准,代表同年龄层中,97~98%人的营养需求量。

AI(足够摄取量 Adequate Intake):未能有足够的实验资讯建立EAR的情形下,所推估维持健康状态的量,常用在一岁以下的婴儿。

硒之上限摄取量 (UL)

年龄 美国 (μg)[7] 台湾 (μg)[8]

0月~ 45 35

3月~ 45 50

6月~ 60 60

9月~ 60 65

1岁~ 90 90

4岁~ 150 135

7岁~ 150(4~8岁) 185

10岁~ 280 280

13岁~ 400(14岁~) 360

16岁~ 400 400

19岁~ 400 400

怀孕期 400 400

哺乳期 400 400

UL(Tolerable Upper Intake Level 上限摄取量):对于97~98%的人不可能产生不良健康影响之每日最大营养摄取量

对硒的特殊需求者[9]

以全静脉注射营养(TPNTotal Parenteral Nutrition)为唯一营养来源者,需要硒的营养补充剂。

有严重肠胃道疾病(例如:克隆氏症)或曾移去一大段小肠者有硒营养缺乏的风险。

碘营养缺乏者。研究指出硒缺乏会恶化碘缺乏的症状,适当补充硒可以缓解碘缺乏症状以及在神经系统的影响。

使用化疗药物者需要硒营养的补充。有研究指出,多种型态的硒可以减少化疗药物(例如:顺铂,cisplatin)所引发肾和骨髓的伤害。

吸收

有机和无机形式的硒都可以很有效率的被吸收,只是发生在不同的肠道部位;吸收率并非调控动物体硒之恒态的机制。十二指肠是硒主要的吸收位置,空肠和回肠则 有少量的吸收,但胃则没有吸收硒之能力。甲硒胺酸的吸收效率比亚硒酸盐(selenite)来的好。含有硒的氨基酸吸收是利用氨基酸运送系统,吸收率可达 到80%。甲硒胺酸的吸收率比硒胺酸好。在某些研究中亚硒酸盐的吸收率可达到85%以上,因与肠道中物质的交互作用,吸收率较有变化。一但吸收后,保留程 度高于硒酸盐。硒酸盐(selenate)的吸收又比亚硒酸盐好,几乎被完全吸收;但并入组织前,大部分会由尿中排除。

维生素A、维生素C、维生素E都会增加硒的吸收,当在小肠腔的榖胱甘肽(glutathione, GSH)浓度低时也会增加吸收。重金属(例:水银)和植酸被认为会抑制硒的吸收。

高剂量的维生素C、锌及重金属(例如:汞)会减少硒的吸收;但若在饮食中合并食用硒及维生素C,硒可以和饮食中的氨基酸形成保护结构而不影响其吸收[10]。

运输

小肠吸收之硒会和运输蛋白结合经血液携带至肝和其他组织。肾脏、肝脏、心脏、胰脏和肌肉都是硒含量较高的组织,肺脏、脑部、骨骼和红血球也含有硒。目前如 何调控硒从组织释放到血浆里或是组织从血浆里吸收的作用机制仍然不明。存在血浆中的硒,与许多不同分子结合成不同的形式存在着。其中最多的就是硒胺酸 (Selenocysteine):由硒原子取代原本在Cysteine中的硫原子而存在,由硒蛋白质P(Selenoprotein P)这个运输蛋白 所携带,而这个运输形式在血浆中也占了一半以上。其它类型的运输形式还有甲硒胺酸(Selenomethionine),由硒原子取代原本在 Methionine中的硫原子而存在,也是由硒蛋白质P所携带;除了这两种有机硒之外,也有无机硒的运输形式:硒酸盐、亚硒酸盐、氢化硒,与在人体血液 中α球蛋白及β球蛋白的硫氢基( sulfhydryl groups)结合,例如:极低密度脂蛋白(VLDL)和低密度脂蛋白(LDL)。

而前述各种带有硒且存在于血浆中的分子,均会被细胞所吸收。而细胞则释放甲基化的硒化物至血浆中,再经由尿液将其排出体外。

分子特性

硒蛋白质P(Selenoprotein P)- 是一种含有硒胺酸的血浆蛋白,也是一种运输蛋白,主要是由肝脏合成,在血浆中大约有50%以上的硒是和含硒蛋白质P结合。含硒蛋白质P的结构最多可以带有十个硒胺酸残基,当硒量下降时也会使残基合成量下降。

α球蛋白(α-globulin)- 其中又分成α 1-globulin及α 2-globulin。两者均为糖蛋白,亦皆可帮助脂质的运输。其中α 2-globulin又有一些不同的功能:帮助血红素的运输、铜运输、血液凝集以及调控氧化酶的活性。

β球蛋白(β-globulin)- 可以帮助脂质的运输以及铁和其他矿物质的运输。

代谢

含硒氨基酸和无机态硒都会在组织中进行代谢。从饮食而来的甲硒胺酸其利用情形和甲硫胺酸相似,可储存在氨基酸代谢池中,用于合成蛋白质,也可代谢成硒胺酸和硒胱胺酸。

硒 胺酸可以从饮食中直接得到,或是经由甲硒胺酸代谢而来。硒胺酸经由selenocysteine β-lyase作用之后产生游离态硒。游离态硒可以从 榖胱甘肽(GSH)得到氢,然后生成硒化物(selenide)。硒化物有两个代谢途径,其一是经过甲基化作用后借由尿液排出体外,或是形成硒代磷酸盐 (selenophosphate),这是体内重要含硒酵素的前驱物,例如5'-脱碘酶(5'-deiodinase)或榖胱甘肽过氧化酶 (glutathione peroxidase)。

从食物中得来的硒酸盐在体内可转换成亚硒酸盐,更进一步代谢成selenodiglutathione及硒离子,后者成为硒蛋白或酵素的原料。

生化功能

硒最主要的功能是作为各种en:selenoprotein硒蛋白的组成分,进而影响其酵素活性或功能。

榖胱甘肽过氧化酶( glutathione peroxidase, GPX)

这 是研究最多的含硒酵素,因为最早发现硒的生化功能就是作为酵素榖胱甘肽过氧化酶的辅基。榖胱甘肽过氧化酶有五种亚型,通常标记为 GPX1, 2, 3, 4, 5,每一种的亚型存在于不同的组织,但是催化相同的反应。主要的功能是消除组织中的过氧化氢(H2O2)和其他有机态过氧 化物。还原过氧化物时,同时利用榖胱甘肽提供还原力(图)[11]。

甲状腺素脱碘酶(Iodothyronine Deiodinases,IDI或DI)

脱碘酶是含硒蛋白质,酵素的活性区是硒胺酸。已知有三种亚型。第一型存在肝脏、肾脏和肌肉,第二型及第三型存在皮肤、脑下垂体、脂肪细胞和脑。主要功能是催化甲状腺素和相关代谢物脱去碘原子(图) 

, 例如:5'-deiodinase(5'-DI)将T4型甲状腺素脱碘转换成T3型甲状腺素,后者是体内活性最高的甲状腺素,可调节代谢、生长及发育。 去碘酶也会将T4转换反式T3(reverse T3),催化产生反式T3的酵素是5-deiodinase。T3或是反式T3都可进一步脱碘产生T2或 是3,3'-diiodothyronine,这些都是没有活性的代谢物。

“硫氧化还原蛋白”还原酶(Thioredoxin Reductase,TrxR)

酵素的活性区有硒胺酸,并含有FAD。此酵素存在血液、皮肤和肝脏等组织。主要反应是将氧化态的“硫氧化还原蛋白”(thioredoxin)中的双硫键(disulfide bond)予以还原。还原态的“硫氧化还原蛋白”可以将氢原子提供给其他化合物(图[12])。

硒代磷酸盐合成酶(Selenophosphate Synthetase)

硒代磷酸盐合成酶有两种亚型,其中一型含硒胺酸,催化硒离子磷酸化成硒代磷酸盐的反应,这是合成含硒蛋白质的必备原料(图)[13]。

硒蛋白质P(Selenoprotein P)

这是硒的运输蛋白质。有移除自由基的作用,具有抗氧化剂的功能。当体内的硒含量不足时,硒蛋白质P会优先获得硒。

硒蛋白质W(Selenoprotein W)

含有硒胺酸,主要存在心肌、骨骼肌和其它组织的细胞质中,可能扮演抗氧化剂的功能。

硒蛋白生合成分子机制

硒 蛋白的硒胺酸是在转译过程合成并直接利用的,称为转译插入反应(translational incorporation)。合成途径需要的蛋白质有: 硒胺酸合成酶selenocysteine synthase、硒半胱胺酸专用延长因子selenocysteine- specific elongation factor、selenocysteine-specific tRNA(tRNASec)、硒代磷酸盐合成 酶 selenophosphate synthetase。硒胺酸对应的基因密码是UGA,此密码通常当做终止密码,但若配合mRNA序列3’端未转译 区域具有独特的二级结构SECIS(selenocysteine insertion sequence),则成为转译硒胺酸的密码。

自 然界中有许多细菌、植物或动物都能利用硒化氢(hydrogen selenide)合成多种有机化合物,如大蒜中的selenide garlic就 是含有高单位的Se-methylselenocysteine。人类需要直接摄取有机的硒化物。自然界中甲硒胺酸(selenomethionine) 插入硒蛋白质中是直接取代甲硫胺酸(methionine)的位置而得。也就是说在含甲硒胺酸的蛋白质合成过程先由甲硫胺酸编入,然后再接上硒成为甲硒胺 酸并没有特殊密码。人类再利用甲硒胺酸释出的硒,先合成磷酸硒(selenophosphate)再生成硒半胱胺酸 (selenocysteine, Sec)或其他小分子,再利用UGA的密码将Sec编入人体的特殊蛋白硒蛋白质。人体硒的储存者可能是硒蛋白 质 P(selenoprotein p),在已被发现的14种硒蛋白质中只有硒蛋白质 P含有10到12个Sec,其Sec数可以随血中硒的浓度而改 变。其他的硒蛋白质都只有单一个Sec。所以硒带蛋白质 P可能是人类硒的储存池,当食物中硒供应不足时硒蛋白质 P就会释出硒供人体利用,但是 至今仍 无法证实其功能。

合成反应主要有四个步骤(图示[14])

步骤一:tRNASec与Serine经由Seryl-tRNA synthetase作用,生成Seryl-tRNASec。

步骤二: 硒离子和ATP经由硒代磷酸盐合成酶反应生成硒代磷酸盐。

步骤三:Seryl-tRNASec和硒代磷酸盐经由硒胺酸合成酶作用,产生含硒氨基酸残基Selenocysteyl-tRNASec。

步骤四:转译时由SBP2和SECIS结合,继而和tRNASec-eEFsec复合物结合,再与核糖体作用而诱导硒胺酸插入蛋白质(图示[15])。

缺乏与毒性

缺乏综合症

动物缺硒

硒 缺乏会引起牲畜类动物疾病。硒缺乏造成硒蛋白质酵素活性下降。若硒以外之营养状况良好,硒缺乏仅造成轻微的临床症状。若伴有营养不良、化学药物、感染等 压力,则会动物会出现严重病症。例如:硒缺乏加上维生素 E缺乏可导致大鼠与猪的之脂质过氧化与肝脏坏死,使猪、牛、羊的心脏损伤。在受感染的小鼠体内, 硒缺乏可导致非致病性的coxsackie B3病毒转变为具致病性的病毒,而造成小鼠的心肌炎。

人体缺硒

人体摄取不足时,会造成克山病(Keshan disease)和溪山症(Kashin-Beck disease)。

克山病的主要病症为心肌病变(cardiomyopathy),包括心律加快、心电图异样、充血性心脏衰竭、心脏组织的多病灶坏疽等,严重时会导致生命危险甚至死亡。

克 山症(Keshan disease)[16]是一种因为饮食缺乏微量元素硒所造成的充血性心肌病变症。此病症的命名来自于中华人民共和国北方的黑龙江 省克山县,黑龙江省克山县是此病高流行的地区,发现是因为此地的土壤缺乏硒。克山症会造成心肌病变,好发于孩童和怀孕的妇女。补充硒可以改善病症,目前也 发现此病症和病毒感染有关;特别是心肌病毒感染,如科萨奇病毒引起的心肌炎或感染过敏性心肌炎。本病的发生除了黑龙江省之外,在吉林、辽宁、内蒙古、河 北、河南、山东、山西、陕西、甘肃、四川、云南、西藏等地区都有病例,且病区多在荒僻山丘、高原及草原的农村,城乡地区较少发病。

克山病 的症状主要是造成扩张性心肌病变(Dilated Cardiomyopathy)。心肌呈变形、坏死、和疤痕形成。心脏扩张肿大,多数左心室扩张 比右心室严重。心脏的切面可以看到大小不等黄色、灰白色坏死、纤维化的疤痕;在显微镜下也可以观察到心肌变性、肌纤维肿大、坏死的现象。适量的硒对缺硒造 成的心肌损害有明显的保护作用及抗氧化能力。硒是GSH-px的组成成分之一,该酶的主要作用是还原脂质过氧化物,清除自由基进而保护细胞膜的完整性。而 低硒会造成GSH-px活性降低,造成心肌膜系统损伤。

克山症的临床症状主要为急性和慢性心功能不全、心脏扩大、心律不整以及脑、肺、肾等栓塞,根据1982年中华人民共和国全国克山病防治经验交流会上的分形如下:

急 性:突然发病的状况,在中华人民共和国北方,急型病多发生在冬季,会因寒冷、过劳、感染、暴饮暴食或分娩等诱因而发病。重症者会出现心源性休克、急性肺 水肿和严重心律失常的症状。一开始可能感到头晕、心窝部不适、反复恶心呕吐、吐黄水,继而烦躁不安。严重者可在数小时或数天内死亡。患者常会面色苍白,四 肢冰冷,血压降低,呼吸减慢。心脏一般轻度大,心音弱,尤其第一心音减弱,舒张期和收缩期会出现杂音。心律不整,主要为室性早搏、阵发性心动过速和房室传 导阻滞。急性心衰竭时肺部出现杂音,此外肝肿大和下肢水肿亦常见。

亚急型:发病不如急型快速。患者多为幼童,2~5岁占85%。以春、夏季发病为多数。会出现心源性休克或充血性心力衰竭。发病初期表现为精神萎靡、咳嗽、呼吸急促、食欲不振、面色灰暗和全身水肿。亦会出现心脏扩大、奔马律和肝肿大。脑、肺、肾等处的栓塞并不少见。

慢 型:起病缓慢,很难被病患所察觉,亦可由急型、亚急型或潜在型转化而来。临床表现主要为慢性充血性心力衰竭,有心悸、呼吸急促,劳累后加重,并会有少 尿、水肿和腹水。体检观察发现心脏向两侧明显扩大,心音低,会听到轻中度收缩期杂音和舒张期奔马律,晚期可能出现右心衰竭的体征如颈静脉恕张、肝肿大和下 肢浮肿等。严重者有胸、腹腔积液,心源性肝硬化等症状。心律不整的症状如室性早搏、心动过速、传导阻滞、心房颤动等。

潜在型:可发生在平 时看似健康的人,亦可为其他型好转的阶段。前者常无症状,可照常劳动或工作,而在普查中被发现,此属稳定的潜在型。由其他型转变而来者 可有心悸、呼吸急促、头昏、无力等症状。心电图会有ST-T变化,QT间期延长和过早搏动。潜在型心脏虽受损,但心功能代偿良好。心脏不增大或轻度增大。

克 山症的预防措施首应注意环境卫生和个人卫生。保护水源,改善水质。改善营养条件,防止偏食,尤其对孕妇、产妇和儿童更应加强补充蛋白质,各种维生素及人 体必需的微量元素,包括镁、碘等,并防治大骨节病、地方性甲状腺病。 且流行区推广预防性服药 采用硒酸钠作为预防性服药,经多年推广,证明可明显降低发 病率。通常采用每10天口服一次,1~5岁1mg,6~10岁2mg,11~15岁3mg,16岁以上4mg。非发病季节可停服三个月。此外,流行区推荐 使用含硒食盐。农村使用含硒液浸过的种子种植。植物根部施加含硒肥料以提高农作物中含硒量。

溪山症的主要病征为骨关节病变(osteoarthropathy),包含骨关节、小腿、手臂的软骨骺版退化与坏死。此疾病为地域性、多发性、变形性骨关节病变,出现于亚洲低硒地区青春期前儿童与青少年。上述症状仅发生于硒缺乏者,但改善硒营养状况并无法完全避免此疾病。

儿童和全静脉营养病人发生硒缺乏时,易导致关节僵硬、肌肉痛、头发和皮肤失去色素颜色、生长迟滞、指甲白化等症状。生长迟滞的现象与硒在甲状腺素的代谢有关。

毒性

化合物形式与毒性

元 素态的硒和大部分的金属硒化物毒性较小,因为生物可用性(bioavailability)小。硒酸盐和亚硒酸盐的毒性较大,硒化氢 (hydrogen selenide)的毒性最大,是一种气状的硒化合物。有机态硒化物如甲硒胺酸和硒胺酸与含硫氨基酸相似,因此毒性较无机态硒为低, 但其吸收率高,虽不致造成急性毒害,但长期大量摄取,会产生与无机硒相似的中毒症状。

硒中毒(selenosis)可能发生在工人以及摄取过多硒的族群。目前订定硒的上限摄取量为400μg/day;硒的副作用发生最低量(LOAEL)为910 μg。摄食过量时,极易导致毛发异样、指甲脱落、脚趾甲异样等副作用,不过并无饮食硒中毒的案例。

中 毒的严重程度与所摄取的硒含量成正比的关系。中毒的症状包含:反胃呕吐、疲劳、腹泻、头发与指甲损坏、异常刺痛感等,也会干扰硫的正常代谢以及抑制蛋白 质合成。服用含有高量硒的药物会造成急性硒中毒,严重过量会导致肝硬化, 肺水肿(pulmonary edema),甚至丧命。治疗硒在体内不平衡所造 成的症状目标:1.降低关节炎症状;2.降低血压;3.改善皮肤、毛发及指(趾)甲问题。

食物硒含量取决于土壤硒含量。美国虽有高硒地区,但农业部(USDA)已确认这些地区,并禁止饲养动物作为食物来源。美加地区食物运销系统发达,可确保个人不会只摄食到当地农产,保障民众硒摄取量不致过高或过低。

硒中毒的生化指标

硒 蛋白质含量在硒需要量达到后,即呈现饱和状态,不再随硒摄取量增加而上升,因此无法被用于评估硒的毒性。测量组织(血液、血浆)的硒含量有助于评估硒中 毒的危险性。尿液硒排除量在特定控制之条件下,可作为硒毒性的指标。临床症状如毛发、指甲易碎裂脱落等常被报道,是主要的评估终点。硒的甲基化代谢物因测 量误差大,且受许多因素影响,不适用于硒中毒指标。

与其他营养素的关系

体内含铅量增多 时会有硒浓度下降的现象。铜不足会降低榖胱甘肽过氧化酶和5'-脱碘酶的活性。硒与甲硫胺酸的利用有关。从食物摄取的硒有一部分是甲硒胺酸 的形式,可作为合成蛋白质的材料。当甲硫胺酸供应不足时,甲硒胺酸会成为它的替代物而用在蛋白质的合成,而不会代谢成为硒离子以供利用,间接引发硒的不 足。铁的缺乏会减少榖胱甘肽过氧化酶的合成,减少组织中的硒浓度。维生素E和榖胱甘肽过氧化酶同样有抗氧化的功能,在使细胞膜和DNA免于自由基的攻击机 制上,硒和维生素E常一起作用,在功能上也有互补作用,其中一者浓度较高会减低另一浓度较低者所造成的影响[17]。

 

 

引用出處: 

 http://www.hudong.com/wiki/%E7%A1%92

歡迎來到Bewise Inc.的世界,首先恭喜您來到這接受新的資訊讓產業更有競爭力,我們是提供專業刀具製造商,應對客戶高品質的刀具需求,我們可以協助客戶滿足您對產業的不同要求,我們有能力達到非常卓越的客戶需求品質,這是現有相關技術無法比擬的,我們成功的滿足了各行各業的要求,包括:精密HSS DIN切削刀具協助客戶設計刀具流程DIN or JIS 鎢鋼切削刀具設計NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計超高硬度的切削刀具醫療配件刀具設計複合式再研磨機PCD地板專用企口鑽石組合刀具粉末造粒成型機主機版專用頂級電桿PCBN刀具PCD刀具單晶刀具PCD V-Cut捨棄式圓鋸片組粉末成型機航空機械鉸刀主機版專用頂級電汽車業刀具設計電子產業鑽石刀具木工產業鑽石刀具銑刀與切斷複合再研磨機銑刀與鑽頭複合再研磨機銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計;從微細刀具到大型刀具;從小型生產到大型量產;全自動整合;我們的技術可提供您連續生產的效能,我們整體的服務及卓越的技術,恭迎您親自體驗!!  

BW Bewise Inc. Willy Chen willy@tool-tool.com  bw@tool-tool.com  www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com/ / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting toolaerospace tool .HSS  DIN Cutting toolCarbide end millsCarbide cutting toolNAS Cutting toolNAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end milldisc milling cutter,Aerospace cutting toolhss drillФрезерыCarbide drillHigh speed steelCompound SharpenerMilling cutterINDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) Core drillTapered end millsCVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden FingerPCD V-CutterPCD Wood toolsPCD Cutting toolsPCD Circular Saw BladePVDD End Millsdiamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE Single Crystal Diamond Metric end millsMiniature end millsСпециальные режущие инструменты Пустотелое сверло Pilot reamerFraisesFresas con mango PCD (Polycrystalline diamond) ‘FresePOWDER FORMING MACHINEElectronics cutterStep drillMetal cutting sawDouble margin drillGun barrelAngle milling cutterCarbide burrsCarbide tipped cutterChamfering toolIC card engraving cutterSide cutterStaple CutterPCD diamond cutter specialized in grooving floorsV-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert PCD Diamond Tool Saw Blade with Indexable InsertNAS toolDIN or JIS toolSpecial toolMetal slitting sawsShell end millsSide and face milling cuttersSide chip clearance sawsLong end millsend mill grinderdrill grindersharpenerStub roughing end millsDovetail milling cuttersCarbide slot drillsCarbide torus cuttersAngel carbide end millsCarbide torus cuttersCarbide ball-nosed slot drillsMould cutterTool manufacturer. 

Bewise Inc.  www.tool-tool.com

ようこそBewise Inc.の世界へお越し下さいませ、先ず御目出度たいのは新たな

情報を受け取って頂き、もっと各産業に競争力プラス展開。

弊社は専門なエンドミルの製造メーカーで、客先に色んな分野のニーズ

豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。

弊社は各領域に供給できる内容は:

(1)精密HSSエンドミルのR&D

(2)Carbide Cutting tools設計

(3)鎢鋼エンドミル設計

(4)航空エンドミル設計

(5)超高硬度エンドミル

(6)ダイヤモンドエンドミル

(7)医療用品エンドミル設計

(8)自動車部品&材料加工向けエンドミル設計

弊社の製品の供給調達機能は:

(1)生活産業~ハイテク工業までのエンドミル設計

(2)ミクロエンドミル~大型エンドミル供給

(3)小Lot生産~大量発注対応供給

(4)オートメーション整備調達

(5)スポット対応~流れ生産対応

弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。     

Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz. 

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт  www.tool-tool.com  для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web  www.tool-tool.com  for more info.

 

beeway 發表在 痞客邦 PIXNET 留言(0) 人氣()

一、引言

隨 著人們環保意識的提高及加入世貿組織後發達國家針對我國設置的綠色壁壘,客觀上要求機械產品在製造時盡可能少地消耗能源和污染環 境。而機械切削(以下簡稱切削)是機械製造中消耗能源和污染環境的最大來源,所以人們有針對性地提 出了綠色切削( 綠色製造 )的概念。所謂綠色切削就是指消 耗盡可能少的刀具材料、切削液、加工時間和電力,盡可能少地污染環境,來達到某種特定的切削目的一種切削方 式。由於高速切削的特點決定了高速切削可以節省切削液、刀具材料、切削工時,從而極大限度地節約自 然資源,極大限度地減少對環境的污染,保護環境,提高生產率和產品質量,達到“綠色切削”的目的。

二、高速切削的特點

1 .切削力小、振動頻率 低

切 削形成的過程分為擠壓塑性變 形和撕裂兩個階段,工件受切削力和切削熱影響而發生塑性變形主要在這個階段。</span> <span>由此可知:切削速度越 高,塑性變形的時間越短,剪切變形區域越窄,剪切角越大,變形因子越小,切屑流出速度越快(切屑中的熱量佔切削熱的 80% ),傳入工件和刀具中的熱量越小,所以高速切削可使切削變形平均減少 30% ~ 40% 以上,這十分適合於剛性較差和薄壁零件的切削加工。

從動力學角度分析頻率的形成可知,切削力 的降低將減小由於切削力產生的振動(即強迫振動)的振幅;轉速的提高使切削系統的工作頻率遠離機床的底階固有頻率,避免共振的發生;因此高速切削可大大降 低加工表面粗糙度,提高加工質量。

2.機床本身特徵

高 速切削機床應用了目前最先進的技術,是 集機、光、電、氣、液壓為一體的、採用了目前所知的最適合機床的複合材料所製成的尖端技術產品。所 以高速切削機床除主軸轉速高外,相對於普通數控機床,其自動化程度(又稱智能化)更高、功率更大、切削材料硬度較高(可高速切 削 HRC50~ 54 甚至 HRC60的材料);精度更高(達到 <span>0.001mm 甚至 0.0001mm )、切削和進給速度高(是普通數控機床的幾倍甚至幾十倍);由於廣泛採用伺服電機, 其傳動系統機械結構簡化且傳動可靠;採用複合材料或人造大理石為基座或工作台(如瑞士 MIKRON的 UCP600 )使機床剛性得到顯著提高,這些都使零件的尺寸精度得到極大提高。

3 .使用先進的刀具

(1 )塗層硬質合金刀具

TiC 塗層:具有很高的硬度與耐磨性,抗氧化性也較好,切削時能形成氧化鈦薄膜,從而降低 了摩擦係數,減小了刀具磨損,使切削速度提高 40% 以上,比較適合高速切削。TiC塗層與鋼的粘結溫度高,表面晶粒很細,切削時很少產生積屑瘤,這比較適合於高速精密 車削。缺點是線膨脹係數與基體差別較大,因此高速車削或銑削硬材料、高溫合金或帶夾雜物工件時,塗 層易崩裂。

TiN 塗層:在高溫時能形成氧化膜,與鐵基材料摩擦係數較小,抗粘結性能好、有效地降低了 摩擦力與切削溫度,TiN 塗層刀片抗月牙窪及後刀面磨損能力比 TiC塗層刀片強,最適合切削鋼與易粘刀的材料,使加工表面粗糙度減小,切削速度提 高。此外 TiN塗層抗碎裂性與抗熱震性能也較好,這很適合於高速切削。但其與基體結合強度低於TiC 塗層,且塗層厚時易剝落,一般用於高速車削。

TiC/TiN 複合塗層:兼具兩種塗層的優點,先塗 TiC ,再塗 TiN ,使結合強度提高,摩擦力、切削力、切削溫度降低,對高速切削中的粗、精加工都很 好。如株硬集團的 CN15、 CN25(精)、 CN35(粗)等。

TiC/AL2O3 複合塗層:先塗TiC,再塗 <AL2O3 。先塗 TiC使塗層粘結牢固,使塗層具有陶瓷的耐磨性、良好的化學穩定性和抗氧化性。該複合刀片能像陶瓷刀一樣高速切削,同時又避免了陶瓷的脆性、易崩刃的特 點,如株硬集團的 CA15 該塗層刀具很適合於高速切 削,特別是高速車削。

塗層刀具具有省貴重材料、易製造、使用時間長等特點,既符合環保的需要又為企業增加了經濟效益,所以被廣泛推薦使用。

陶瓷刀具

 

該材料以氧化鋁為主要成分,在高溫下燒結而成。

 

 

引用出處: 

 http://tw.myblog.yahoo.com/lifung-biz/article?mid=4413&prev=4414&next=4409

歡迎來到Bewise Inc.的世界,首先恭喜您來到這接受新的資訊讓產業更有競爭力,我們是提供專業刀具製造商,應對客戶高品質的刀具需求,我們可以協助客戶滿足您對產業的不同要求,我們有能力達到非常卓越的客戶需求品質,這是現有相關技術無法比擬的,我們成功的滿足了各行各業的要求,包括:精密HSS DIN切削刀具協助客戶設計刀具流程DIN or JIS 鎢鋼切削刀具設計NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計超高硬度的切削刀具醫療配件刀具設計複合式再研磨機PCD地板專用企口鑽石組合刀具粉末造粒成型機主機版專用頂級電桿PCBN刀具PCD刀具單晶刀具PCD V-Cut捨棄式圓鋸片組粉末成型機航空機械鉸刀主機版專用頂級電汽車業刀具設計電子產業鑽石刀具木工產業鑽石刀具銑刀與切斷複合再研磨機銑刀與鑽頭複合再研磨機銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計;從微細刀具到大型刀具;從小型生產到大型量產;全自動整合;我們的技術可提供您連續生產的效能,我們整體的服務及卓越的技術,恭迎您親自體驗!!  

BW Bewise Inc. Willy Chen willy@tool-tool.com  bw@tool-tool.com  www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com/ / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting toolaerospace tool .HSS  DIN Cutting toolCarbide end millsCarbide cutting toolNAS Cutting toolNAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end milldisc milling cutter,Aerospace cutting toolhss drillФрезерыCarbide drillHigh speed steelCompound SharpenerMilling cutterINDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) Core drillTapered end millsCVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden FingerPCD V-CutterPCD Wood toolsPCD Cutting toolsPCD Circular Saw BladePVDD End Millsdiamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE Single Crystal Diamond Metric end millsMiniature end millsСпециальные режущие инструменты Пустотелое сверло Pilot reamerFraisesFresas con mango PCD (Polycrystalline diamond) ‘FresePOWDER FORMING MACHINEElectronics cutterStep drillMetal cutting sawDouble margin drillGun barrelAngle milling cutterCarbide burrsCarbide tipped cutterChamfering toolIC card engraving cutterSide cutterStaple CutterPCD diamond cutter specialized in grooving floorsV-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert PCD Diamond Tool Saw Blade with Indexable InsertNAS toolDIN or JIS toolSpecial toolMetal slitting sawsShell end millsSide and face milling cuttersSide chip clearance sawsLong end millsend mill grinderdrill grindersharpenerStub roughing end millsDovetail milling cuttersCarbide slot drillsCarbide torus cuttersAngel carbide end millsCarbide torus cuttersCarbide ball-nosed slot drillsMould cutterTool manufacturer. 

Bewise Inc.  www.tool-tool.com

ようこそBewise Inc.の世界へお越し下さいませ、先ず御目出度たいのは新たな

情報を受け取って頂き、もっと各産業に競争力プラス展開。

弊社は専門なエンドミルの製造メーカーで、客先に色んな分野のニーズ

豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。

弊社は各領域に供給できる内容は:

(1)精密HSSエンドミルのR&D

(2)Carbide Cutting tools設計

(3)鎢鋼エンドミル設計

(4)航空エンドミル設計

(5)超高硬度エンドミル

(6)ダイヤモンドエンドミル

(7)医療用品エンドミル設計

(8)自動車部品&材料加工向けエンドミル設計

弊社の製品の供給調達機能は:

(1)生活産業~ハイテク工業までのエンドミル設計

(2)ミクロエンドミル~大型エンドミル供給

(3)小Lot生産~大量発注対応供給

(4)オートメーション整備調達

(5)スポット対応~流れ生産対応

弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。     

Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz.

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт  www.tool-tool.com  для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web  www.tool-tool.com  for more info.

 

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日 本東芝及東洋紡開發出用於手機等外殼(Body)之樹脂表面,埋入薄型天線(Antenna)的新技術。將由樹脂及金屬粉末製成的新材料,塗在外殼樹脂的 表面製作出電路。最新的手機可內藏5個以上的天線,在多功能化的需求下,更不斷追求天線的小型化,期望可在一年內達到實用等級的開發技術,並早日搭載於產 品上。

新開發的技術係將樹脂及金屬粉末製作成具導電性的Paste,之後塗在手機等 外殼的Polycarbonate ABS樹脂,製作電路以作為天線。係在多種類樹脂搭配的材料中,混入金屬粉末再溶入溶劑中,製作出具導電性的Paste。然後再以柔軟的矽當作印章,將電 路圖形(Pattern)於手機外殼等樹脂表面進行印刷。再以攝氏70℃加熱,溶劑揮發之後導電性Paste就會固化,銅等就會鍍在表面上形成天 線。

在樹脂上所製作埋入的天線,在攝氏60℃、濕度95%的高溫高濕測試中並無出現問 題,也顯示出其耐久性。今後將朝量 產化技術進行研發。以往雖有導電性Paste的材料,但使其固化溫度至少要130℃以上,可能會有使外殼樹脂因此溶解的危險。在手機、NB等攜帶型機器小 型化的趨勢中,為增加使用功能所搭載之天線也隨之增加,不過天線可搭載的面積是受到限制的。若採用新技術,只需要在外殼塗上厚度20微米的電路就大功告 成,將天線所使用的容積降低至一半以下。

 

圖:天線埋入之新技術示意圖

資料來源: 日經產業新聞/材料世界網整理

 

 

  

 

歡迎來到Bewise Inc.的世界,首先恭喜您來到這接受新的資訊讓產業更有競爭力,我們是提供專業刀具製造商,應對客戶高品質的刀具需求,我們可以協助客戶滿足您對產業的不同要求,我們有能力達到非常卓越的客戶需求品質,這是現有相關技術無法比擬的,我們成功的滿足了各行各業的要求,包括:精密HSS DIN切削刀具協助客戶設計刀具流程DIN or JIS 鎢鋼切削刀具設計NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計超高硬度的切削刀具醫療配件刀具設計複合式再研磨機PCD地板專用企口鑽石組合刀具粉末造粒成型機主機版專用頂級電桿PCBN刀具PCD刀具單晶刀具PCD V-Cut捨棄式圓鋸片組粉末成型機航空機械鉸刀主機版專用頂級電汽車業刀具設計電子產業鑽石刀具木工產業鑽石刀具銑刀與切斷複合再研磨機銑刀與鑽頭複合再研磨機銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計;從微細刀具到大型刀具;從小型生產到大型量產;全自動整合;我們的技術可提供您連續生產的效能,我們整體的服務及卓越的技術,恭迎您親自體驗!!  

BW Bewise Inc. Willy Chen willy@tool-tool.com  bw@tool-tool.com  www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com/ / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting toolaerospace tool .HSS  DIN Cutting toolCarbide end millsCarbide cutting toolNAS Cutting toolNAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end milldisc milling cutter,Aerospace cutting toolhss drillФрезерыCarbide drillHigh speed steelCompound SharpenerMilling cutterINDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) Core drillTapered end millsCVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden FingerPCD V-CutterPCD Wood toolsPCD Cutting toolsPCD Circular Saw BladePVDD End Millsdiamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE Single Crystal Diamond Metric end millsMiniature end millsСпециальные режущие инструменты Пустотелое сверло Pilot reamerFraisesFresas con mango PCD (Polycrystalline diamond) ‘FresePOWDER FORMING MACHINEElectronics cutterStep drillMetal cutting sawDouble margin drillGun barrelAngle milling cutterCarbide burrsCarbide tipped cutterChamfering toolIC card engraving cutterSide cutterStaple CutterPCD diamond cutter specialized in grooving floorsV-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert PCD Diamond Tool Saw Blade with Indexable InsertNAS toolDIN or JIS toolSpecial toolMetal slitting sawsShell end millsSide and face milling cuttersSide chip clearance sawsLong end millsend mill grinderdrill grindersharpenerStub roughing end millsDovetail milling cuttersCarbide slot drillsCarbide torus cuttersAngel carbide end millsCarbide torus cuttersCarbide ball-nosed slot drillsMould cutterTool manufacturer.

Bewise Inc.  www.tool-tool.com

ようこそBewise Inc.の世界へお越し下さいませ、先ず御目出度たいのは新たな

情報を受け取って頂き、もっと各産業に競争力プラス展開。

弊社は専門なエンドミルの製造メーカーで、客先に色んな分野のニーズ

豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。

弊社は各領域に供給できる内容は:

(1)精密HSSエンドミルのR&D

(2)Carbide Cutting tools設計

(3)鎢鋼エンドミル設計

(4)航空エンドミル設計

(5)超高硬度エンドミル

(6)ダイヤモンドエンドミル

(7)医療用品エンドミル設計

(8)自動車部品&材料加工向けエンドミル設計

弊社の製品の供給調達機能は:

(1)生活産業~ハイテク工業までのエンドミル設計

(2)ミクロエンドミル~大型エンドミル供給

(3)小Lot生産~大量発注対応供給

(4)オートメーション整備調達

(5)スポット対応~流れ生産対応

弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。   

Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz.

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт  www.tool-tool.com  для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web  www.tool-tool.com  for more info.

 

beeway 發表在 痞客邦 PIXNET 留言(0) 人氣()

剛剛在德國落幕的Cebit Show中(全球知名且每年固定在德國漢諾威舉行之電腦與通訊大會),為人注目的焦點之一是全球定位技術及系統的發展。眾所週知,代表歐洲衛星定位技術服 務的新里程碑,就在今年2008年邁開一大步,換言之,多年來,歐洲各國積極從事的伽利略衛星定位網路,將於今年正式啟用。屆時,這個號稱比美國衛星定位 系統GPS更佳提供定位精準度的新的衛星定位網路,將掀起更大的應用風潮。

有鑑於定 位技術的應用日漸擴大與展現歐洲伽利略衛星優越的定位追蹤能力,一家以生產定位晶片、模組與服務的知名廠商u-blox特別在會場中展示其u-blox 5 A-GPS和GALILEO-ready晶片在伽利略(GALILEO)衛星追蹤能力。

u- blox是一個可以支援50個通道的定位引擎,它的特色除了可以同時追蹤美國GPS與歐洲伽利略衛星外,同時更 可將定位時間縮減至一秒之內,由於這項功能的提供,將使該項晶片成為全球最快定位引擎。此外,第五代晶片u-blox也能提供離線服務 -AssistNow Offline,透過有效期限長達14日的離線輔助資料功能,將提供一些不需要每次開機都需連線的應用。目前,u-blox 5晶片和模組都已量產上市了。

另外,與行動裝置定位技術相關的重要產業消息包括 EGPS Forum的即將成立。這個以評估和促進「強化GPS」 (enhanced Global Positioning System; EGPS) 技術發展的產業組織,其發起組織為CSR與Motorola等,其成立目的在於廣泛評估和促進「強化GPS」 (enhanced Global Positioning System; EGPS) 技術發展。

EGPS主要針對行動裝置所開發的技術,其可在非常嚴苛的環境下,依舊提供即時且準確的定位資訊。所倡導的EGPS論壇將提供合乎消費者及法規所追求的精確且一致的定位資訊,預期將帶動行動裝置定位技術的蓬勃發展。

 

CSR和Motorola計劃將在2008年上半年備妥EGPS現場測試和效能測試程序,並大力推廣此項技術及其應用。

表一、u-blox 5 GPS Chips規格說明

 

資料來源:u-blox公司網站(2008/3)

 

 

 

引用出處: 

 http://www.materialsnet.com.tw/DocView.aspx?id=6759

歡迎來到Bewise Inc.的世界,首先恭喜您來到這接受新的資訊讓產業更有競爭力,我們是提供專業刀具製造商,應對客戶高品質的刀具需求,我們可以協助客戶滿足您對產業的不同要求,我們有能力達到非常卓越的客戶需求品質,這是現有相關技術無法比擬的,我們成功的滿足了各行各業的要求,包括:精密HSS DIN切削刀具協助客戶設計刀具流程DIN or JIS 鎢鋼切削刀具設計NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計超高硬度的切削刀具醫療配件刀具設計複合式再研磨機PCD地板專用企口鑽石組合刀具粉末造粒成型機主機版專用頂級電桿PCBN刀具PCD刀具單晶刀具PCD V-Cut捨棄式圓鋸片組粉末成型機航空機械鉸刀主機版專用頂級電汽車業刀具設計電子產業鑽石刀具木工產業鑽石刀具銑刀與切斷複合再研磨機銑刀與鑽頭複合再研磨機銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計;從微細刀具到大型刀具;從小型生產到大型量產;全自動整合;我們的技術可提供您連續生產的效能,我們整體的服務及卓越的技術,恭迎您親自體驗!!  

BW Bewise Inc. Willy Chen willy@tool-tool.com  bw@tool-tool.com  www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com/ / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting toolaerospace tool .HSS  DIN Cutting toolCarbide end millsCarbide cutting toolNAS Cutting toolNAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end milldisc milling cutter,Aerospace cutting toolhss drillФрезерыCarbide drillHigh speed steelCompound SharpenerMilling cutterINDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) Core drillTapered end millsCVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden FingerPCD V-CutterPCD Wood toolsPCD Cutting toolsPCD Circular Saw BladePVDD End Millsdiamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE Single Crystal Diamond Metric end millsMiniature end millsСпециальные режущие инструменты Пустотелое сверло Pilot reamerFraisesFresas con mango PCD (Polycrystalline diamond) ‘FresePOWDER FORMING MACHINEElectronics cutterStep drillMetal cutting sawDouble margin drillGun barrelAngle milling cutterCarbide burrsCarbide tipped cutterChamfering toolIC card engraving cutterSide cutterStaple CutterPCD diamond cutter specialized in grooving floorsV-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert PCD Diamond Tool Saw Blade with Indexable InsertNAS toolDIN or JIS toolSpecial toolMetal slitting sawsShell end millsSide and face milling cuttersSide chip clearance sawsLong end millsend mill grinderdrill grindersharpenerStub roughing end millsDovetail milling cuttersCarbide slot drillsCarbide torus cuttersAngel carbide end millsCarbide torus cuttersCarbide ball-nosed slot drillsMould cutterTool manufacturer. 

Bewise Inc.  www.tool-tool.com

ようこそBewise Inc.の世界へお越し下さいませ、先ず御目出度たいのは新たな

情報を受け取って頂き、もっと各産業に競争力プラス展開。

弊社は専門なエンドミルの製造メーカーで、客先に色んな分野のニーズ

豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。

弊社は各領域に供給できる内容は:

(1)精密HSSエンドミルのR&D

(2)Carbide Cutting tools設計

(3)鎢鋼エンドミル設計

(4)航空エンドミル設計

(5)超高硬度エンドミル

(6)ダイヤモンドエンドミル

(7)医療用品エンドミル設計

(8)自動車部品&材料加工向けエンドミル設計

弊社の製品の供給調達機能は:

(1)生活産業~ハイテク工業までのエンドミル設計

(2)ミクロエンドミル~大型エンドミル供給

(3)小Lot生産~大量発注対応供給

(4)オートメーション整備調達

(5)スポット対応~流れ生産対応

弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。     

Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz. 

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт  www.tool-tool.com  для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web  www.tool-tool.com  for more info.

 

beeway 發表在 痞客邦 PIXNET 留言(0) 人氣()

钪(旧译作 鉰、鏮)是一种柔软、银白色的过渡性金属,熔点1541℃。沸点2831℃。常见化合价+3。第一电离能为6.54电子伏特。易溶于水,可与热水作用,在 空气中容易变暗。常跟钆、铒等混合存在,产量很少。钪在地壳中的含量约为0.0005%,主要矿物为钪钇石,钪也存在于核裂变产物中,自然界存在的钪全部 为稳定同位素钪45。

纠错 编辑摘要

目录

  • 1 概述
  • 2 元素性质
  • 3 发现
  • 4 制取
  • 5 应用
  •  

  • 1 概述
    • 1.1 简介
    • 1.2 发现
  • 2 元素性质
    • 2.1 总体特性 
    • 2.2 原子属性
    • 2.3 物理属性
    • 2.4 其他性质
    • 2.5 地质数据
    • 2.6 人体中含量 
  • 3 发现
  • 4 制取
  • 5 应用
    • 5.1 钪的第一件法宝
    • 5.2 钪的第二件法宝
    • 5.3 钪的第三件法宝
  • 6 神奇的调料
  • 7 钪对人的作用
  • 8 相关词条
  • 9 参考资料

 

钪 - 概述

简介

 

钪 (旧译作鉰、鏮)是稀土元素之一,为银白色金属,质较软;熔点1541°C,沸点 2831°C,密度2.989克/厘米³。晶体结构有六方密堆积(1335°C以下)和体心立方。第一电离能为6.54电子伏特。钪在化合物中主要呈3价 态,易溶于水,可与热水作用放出氢,也易溶于酸,是一种强还原剂。在空气中容易氧化成Sc2O3而失去金属光泽变成暗灰色。钪的氧化物及氢氧化物只显碱 性,但其盐灰几乎不能水解。氧化钪为白色粉末,易溶于酸中生成相应的盐。 钪的氯化物为白色结晶,易溶于水并能在空气中潮解。钪的离子半径较小,形成配位 化合物的能力较强;钪能与多种氨羧络合剂生成稳定的螯合物;钪能与茜素和苯胂酸等有机试剂生成有色配合物,这个性质被用于钪的比色分析和光谱分析。常跟 钆、铒等混合存在,产量很少。钪在地壳中的含量约为0.0005%,主要矿物为钪钇石,钪也存在于核裂变产物中,自然界存在的钪全部为稳定同位素钪45。 另外,钪还有9种放射性同位素,即40~44Sc和46~49Sc。其中,46Sc作为示踪剂,已在化工、冶金及海洋学等方面使用。在医学上,国外还有人 研究用46Sc来医治癌症。

发现

 

1817年门捷列夫根据他的元素周期律,预言“类硼”的存在和性质;1879年瑞典的尼尔森从硅铍钇矿和黑稀金矿中分离出钪的氧化物;瑞典的克莱夫在研究钪的性质后,确认就是门捷列夫语言的“类硼”。

元素来源:

主要以矿物 thortveitile 和 wiikite 存在。在一些锡、钨矿中也含有钪,从钨矿、锡石及含有其他稀土的矿石中回收制得,主要矿物为钪钇石,极稀少。 

 

钪 - 元素性质

 

总体特性 

 

中文名称 钪

英文名称 Scandium

元素符号 Sc

原子序数 21

系列 过渡金属

族 3族

周期4

元素分区d

密度 2985kg/m3

颜色和外表 银白色

质地:质软

地壳含量 5×10-4 %

原子属性

相对原子质量 44.955912(6)原子量单位

原子半径(计算值)160(184)pm

共价半径 144 pm

 

钪元素性质数据

价电子排布 [氩]3d14s2

电子在每能级的排布 2,8,9,2

氧化价(氧化物 3(弱碱性)

晶体结构 六方密排晶格

晶胞参数:

a = 330.9 pm

b = 330.9 pm

c = 527.33 pm

α = 90°

β = 90°

γ = 120°

物理属性

物质状态 固态

熔点 1814 K(1541 °C)

沸点 3103 K(2830 °C)

摩尔体积 15.00×10-6m3/mol

汽化热 314.2 kJ/mol

熔化热 14.1 kJ/mol

蒸气压 22.1 帕(1812K)

声速 无数据(293.15K)

其他性质

电负性 1.36(鲍林标度)

比热 568 J/(kg•K)

电导率 1.77×106/(米欧姆)

热导率 15.8 W/(m•K)

第一电离能 633.1 kJ/mol

第二电离能 1235.0 kJ/mol

第三电离能 2388.6 kJ/mol

第四电离能 7090.6 kJ/mol

第五电离能 8843 kJ/mol

第六电离能 10679 kJ/mol

第七电离能 13310 kJ/mol

第八电离能 15250 kJ/mol

第九电离能 17370 kJ/mol

第十电离能 21726 kJ/mol

同位素 丰度 半衰期 衰变模式 衰变能量MeV 衰变产物

45Sc  100 % 稳定

46Sc  人造 83.79天 β衰变  2.367  46Ti

地质数据

滞留时间/年: 5000

太阳(相对于 H=1×1012): 1100

地壳/p.p.m.: 16

大西洋表面: 6.1 × 10-7 

太平洋表面:3.5 × 10-7

大西洋深处: 8.8 × 10-7 

太平洋深处:7.9 × 10-7

人体中含量 

血/mg dm-3 : c. 0.008

日摄入量/mg: c. 0.00005

人(70Kg)均体内总量/mg: c. 0.2

 

钪 - 发现

发现人:尼尔森 

发现年代:1876年

发现过程:

1879 年,瑞典的 化学教授尼尔森(L.F.Nilson, 1840~1899)和克莱夫(P.T.Cleve, 1840~1905)差不多同时在稀有的矿物硅铍钇矿和 黑稀金矿中找到了一种新元素。他们给这一元素定名为"Scandium"(钪),钪就是门捷列夫当初所预言的"类硼"元素。他们的发现再次证明了元素周期 律的正确性和门捷列夫的远见卓识。随着钪以及其他一些稀土元素的发现,完成了发现稀土元素第三阶段的另一半。

发现历史:

在 元素化学里,有一系列性质非常接近的金属元素被称为稀土元素。这一系列中包括了十五个镧系元素--镧(La)、铈(Ce)、镨(Pr)、钕(Nd)、钷 (Pm)、钐(Sm)、铕(Eu)、钆(G d)、铽(Tb)、镝(Dy)、钬(Ho)、铒(Er)、铥(Tm)、镱(Yb)、镥(Lu);以及和这些同族而性质相似的两个更轻的元素:钪(Sc)和 钇(Y)。这一系列元素最初是从瑞典产的比较稀少的矿物中发现的,"土"是当时对不溶于水的金属氧化物的统称,因此得名稀土(Rareearth)。在这 十七个元素里面,钪的排位是最靠前的,原子序数只有21,不过就发现而言,钪比他在元素周期表上面的左邻右舍都要晚了差不多上百年,即使在稀土里面,钪的 发现也不是较早的,排列在钇、铈、镧、铒、铽和镱后面,名列第七。

    门捷列夫的预言没有得到人们的注意,但是在十九世纪晚期,对稀土元素的研究却成为了一股热潮。在钪发现之前一年,瑞士的马利纳克 (deMarignac) 从玫瑰红色的铒土中,通过局部分解硝酸盐的方式,得到了一种不同于铒土的白色氧化物,他将这种氧化物命名为镱土,这就是稀土元素发现里面的第六名。当时老 马手头样品没多少 了,就建议手头有充足铒土的科学家多制备一些镱土,以研究它的性质。当时瑞典乌泼撒拉大学的尼尔森手头正好有铒土的样品,他就想按照马利纳克的方法将铒土 提纯,并精确测量铒和镱的原子量(因为他这个时候正在专注于精确测量稀土元素的物理与化学常数以期对元素周期律作出验证)。当他经过13次局部分解之后, 得到了3.5g纯净的镱土。但是这时候奇怪的事情发生了,马利纳克给出的镱的原子量是172.5,而尼尔森得到的则只有167.46。

    尼尔森敏 锐地意识到这里面有可能是什么轻质的元素鱼目混珠进去,才让这个原子量的测定不再准斤足两。于是他将得到的镱土又用相同的流程继续处理,最后当只剩下十分 之一样品的时候,测得的原子量更是掉到了134.75;同时光谱中还发现了一些新的吸收线。尼尔森的判断是正确的,因此也就获得了给孩子起名的权利。他用 他的故乡斯堪的纳维亚半岛给钪命名为Scandium。1879年,他正式公布了自己的研究结果,在他的论文中,还提到了钪盐和钪土的很多化学性质。不过 在这篇论文中,他没有能给出钪的精确原子量,也还不确定钪在元素周期中的位置。

    尼尔森的好友,也是同在乌泼撒拉大学任教的克利夫也在一起做这个工作。他从铒土出发,将铒土作为大量组分排除掉,再分出镱土和钪土之后,又从剩余物中找 到了钬和铥这两个新的稀土元素。做为副产物,他提纯了钪土,并进一步了解了钪的物理和化学性质。这样一来,门捷列夫放出的漂流瓶沉睡了十年之后,终于被克 利夫捞了起来,他认识到,钪,就是门捷列夫的类硼。我们来看看钪的一些化学性质和瓶中那张古旧的羊皮纸上写过的预言是否吻合吧。

    Eka-Boron Scandium

原子量 44 45.1(克利夫,1879)

原子体积:(立方厘米/摩尔)15.0

地壳中含量:(ppm)16

元素在太阳中的含量:(ppm) 0.04

元素在海水中的含量:(ppm)

太平洋表面 0.00000035

44.955910(IUPAC,现代)

可以形成Eb2O3形式的化合物,其比重3.5,碱性强于氧化铝,弱于氧化钇和氧化镁;是否能与氯化铵反应还是疑问。钪土Sc2O3,其比重3.86,碱性强于氧化铝,弱于氧化钇和氧化镁,与氯化铵不反应。

盐类无色,与氢氧化钾和碳酸钠形成胶体沉淀,各种盐类均难以完好结晶。钪盐无色,与氢氧化钾和碳酸钠形成胶体沉淀,硫酸盐极难结晶。

碳酸盐不溶于水,可能形成碱式碳酸盐沉淀。碳酸钪不溶于水,并容易脱掉二氧化碳。

硫酸复盐可能不形成矾。 钪的硫酸复盐不成矾。

无水氯化物EbCl3挥发性低于氯化铝,比氯化镁更容易水解。 ScCl3升华温度850oC,AlCl3则为100oC,在水溶液中水解。

Eb不由光谱发现。 Sc不由光谱发现。

在那个不但对于元素的电子层结构一无所知(连电子都是1899年才发现的),甚至还有权威如杜马这样的化学家对原子论都持怀疑态度。能将一个未发现的元素的性质描述得如此精准,真是让读者后背泛起一层隐隐的凉意。

 

钪 - 制取

 

钪合金

 

在 被发现后相当长一段时间里,因为难于制得,钪的用途一直没有表现出来。随着对稀土元素分离方法的日益改进,如今用于提纯钪的化合物,已经有了相当成熟的工 艺流程。因为钪比起钇和镧系元素来,氢氧化物的碱性是最弱的,所以包含了钪的稀土元素混生矿,经过处理转入溶液后用氨(或极稀的碱)处理时,氢氧化钪将首 先析出,故应用"分级沉淀"法可比较容易地把它从稀土元素中分离出来。

另一种方法是利用硝酸盐的分极分解进行分离,由于硝酸钪最容易分解,可以达到分离出钪的目的。

用电解的方法可制得金属钪,在炼钪时将ScCl3、KCl、LiCl共熔,以熔融的锌为阴极电解之,使钪在锌极上析出,然后将锌蒸去可得金属钪。

另外,在加工矿石生产铀、钍和镧系元素时易回收钪。在铀、钍、钨、锡等矿藏中综合回收伴生的钪也是钪的重要来源之一。

 

钪 - 应用

 

钪用途

 

1,在冶金工业中,钪常用于制造合金(合金的添加剂),以改善合金的强度、硬度和耐热和性能。如,在铁水中加入少量的钪,可显著改善铸铁的性能,少量的钪加入铝中,可改善其强度和耐热性。

2,在电子工业中,钪可用作各种半导体器件,如钪的亚硫酸盐在半导体中的应用已引起了国内外的注意,含钪的铁氧体在计算机磁芯中也颇有前途。

3,在化学工业上,用钪化合物作酒精脱氢及脱水剂,生产乙烯和用废盐酸生产氯时的高效催化剂。

4,在玻璃工业中,可以制造含钪的特种玻璃。

5,在电光源工业中,含钪和钠制成的钪钠灯,具有效率高和光色正的优点。

6,自然界中钪均以45Sc形式存在,另外,钪还有9种放射性同位素,即40~44Sc和46~49Sc。其中,46Sc作为示踪剂,已在化工、冶金及海洋学等方面使用。

7,在医学上,国外还有人研究用46Sc来医治癌症。

钪的第一件法宝

钪 的第一件法宝叫做钪钠灯,可以用来给千家万户带来光明。这是一种金属卤化物电光源:在灯泡中充入碘化钠和碘化钪,同时加入钪和钠箔,在高压放电 时,钪离子和钠离子分别发出他们的特征发射波长的光,钠的谱线为589.0和589.6nm两条著名的黄色光线,而钪的谱线为361.3~424.7nm 的一系列近紫外和蓝色光发射,因为互为补色,产生的总体光色就是白色光。正是由于钪钠灯具有发光效率高、光色好、节电、使用寿命长和破雾能力强等特点,使 其可广泛用于电视摄像和广场、体育馆、马路照明,被称为第三代光源。在中国这种灯还是作为新技术被逐渐推广的,而在一些发达国家,这种灯早在80年代初就 被广泛使用了。

钪的第二件法宝

钪的第二件法宝是太阳能光电池,可以将撒落地面的光明收集起来,变成推动人类社会的电力。在金属-绝缘体-半导体硅光电池和太阳能电池中,钪是最好的阻挡金属。

钪的第三件法宝

他 的第三件法宝叫做γ射线源, 这个法宝自己就能大放光明,不过这种光亮我们肉眼接收不到,是高能的光子流。我们平常从矿物中提炼出来的是45Sc,这是钪的唯一一种天然同位素,每一个 45Sc的原子核中有21个质子和24个中子。倘若我们像把猴子放到太上老君的炼丹炉中炼上七七四十九天一样将钪放在核反应堆中,让他吸收中子辐射,原子 核中多一个中子的46Sc就诞生了。46Sc这种人工放射性同位素可以当作γ射线源或者示踪原子,还可以用来对恶性肿瘤进行放射治疗。还有像钇镓钪石榴石 激光器,氟化钪玻璃红外光导纤维,电视机上钪涂层的阴极射线管之类的用途简直不知凡几,看来钪生来就和光明有缘呢。

 

钪 - 神奇的调料

 

金属钪

上 面说了钪的一些应用,不过因为价格高昂,考虑到成本在工业产品里很少会用到很大数量钪和钪的化合物,都是像灯泡里那样薄薄的一层钪箔之类的用法。而在更多 一些领域,钪和钪的化合物更是被作为神奇的调料使用,好像大厨手中的盐、糖或味精,只需要一星半点,就有画龙点睛的作用。

在无机化学里,掺 杂是一个非常重要的手段。在一个作为基体的晶体结构中掺入少量的其他化合物,因为被掺杂物质在化学性质上和原有基体的不同,晶格结 构会出现各种各样的变化和缺陷,从而或者提升原有基体的性质,或者增添原来不具有的活性。比如大家最耳熟能详的P型和N型半导体原料,就是分别在导通能力 很差的单晶硅里面,添加了因为缺少价电子导致空穴的硼,和因为富余价电子而产生自由电子的磷获得的。我们的钪也是一个重要的掺杂原料,很多材料就是因为掺 入了钪获得了意料之外的性质。

单质形式的钪,已经被大量应用于铝合金的掺杂。在铝中只要加入千分之几的钪就会生成Al3Sc新相,对铝合 金起变质作用,使合金的结构和性能发生明 显变化。加入0.2%~0.4%的Sc(这个比例也真的和家里炒菜放盐的比例差不多,只需要那么一点)可使合金的再结晶温度提高150~200℃,且高温 强度、结构稳定性、焊接性能和抗腐蚀性能均明显提高,并可避免高温下长期工作时易产生的脆化现象。高强高韧铝合金、新型高强耐蚀可焊铝合金、新型高温铝合 金、高强度抗中子辐照用铝合金等,在航天、航空、舰船、 核反应堆以及轻型汽车和高速列车等方面具有非常诱人的开发前景。钪也是铁的优良改化剂,少量钪可显著提高铸铁的强度和硬度。另外,钪还可用作高温钨和铬合 金的添加剂。当然,除了为他人做嫁衣裳之外,因为钪具有较高熔点,而其密度却和铝接近,也被应用在钪钛合金和钪镁合金这样的高熔点轻质合金上,但是这样的 稀罕东西恐怕只有航天飞机和火箭上才舍得用了,要是拿来做自行车架子,这个价值摆出去恐怕一天能被偷上二三十次。

单质的钪一般应用于合 金,而钪的氧化物也是物以类聚地在陶瓷材料上面起到了重要的作用。像可以用作固体氧化物燃料电池电极材料的四方相氧化锆陶瓷材 料有一种很特别的性质,在这种电解质的电导会随着温度和环境中氧的浓度增高而增大。但是这种陶瓷材料的晶体结构本身不能稳定存在,不具有工业价值;必须要 在其中掺杂一些能够将这种结构固定下来的物质才能够保持原有的性质。掺入6-10%的氧化钪就好像混凝土结构一样,让氧化锆能够稳定在四方形的晶格上。还 有像给高强度,耐高温的 工程陶瓷材料氮化硅做增密剂和稳定剂。氧化钪作为增密剂,可以在细小颗粒的边缘生成难熔相Sc2Si2O7,从而减小工程陶瓷的高温变形性,与添加其它氧 化物相比能更好改善氮化硅的高温机械性能。在高温反应堆核燃料中UO2加入少量Sc2O3可避免因UO2向U3O8转化发生的晶格转变、体积增大和出现裂 纹。

在有机化学上钪也并非默默无闻,不过在有机反应里面钪的作用虽然同样是一种调料,却和在无机材料里面用于掺杂不同,而是被作为催化剂 使用。 Sc2O3可用于乙醇或异丙醇脱水和脱氧、乙酸分解,由CO和H2制乙烯等等中。含Sc2O3的Pt-Al催化剂更是在石油化工中作为重油氢化提净,精炼 流程的重要催化剂。而在诸如异丙苯催化裂化反应中,Sc-Y沸石催化剂比硅酸铝的活性大1000倍;和一些传统的催化剂比起来,钪催化剂的发展前景将是很 光明的。

 

从 尼尔森注意到原子量数据的亏欠到今天,钪进入人们的视野不过一百年二十多年,却差不多坐了一百年的冷板凳,直到上个世纪后期材料科学的蓬勃发展才给他带来 了生机。到今天,连同钪在内的稀土元素都已经成为了材料科学中炙手可热的明星,在成千上万的体系中发挥着千变万化的作用,每天都在给我们的生活带来多一点 的便利,创造的经济价值更是难以计量。按阴阳五行的说法,土生金,其信然乎?

 

钪 - 钪对人的作用

钪对于人来说是不是必需元素,目前尚无定论。人体中钪微量存在。怀疑其有致癌性。钪容易与8-羟基喹啉形成络合物这种络合物的形成可以用于对钪的分析。用中子放射性分析法可以测定ng/g以下的钪定量。

 

引用出處: 

 http://www.hudong.com/wiki/%E9%92%AA

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Scandium ( /ˈskændiəm/ SKAN-dee-əm) is a chemical element with symbol Sc and atomic number 21. A silvery-white metallic transition metal, it has historically been sometimes classified as a rare earth element, together with yttrium and the lanthanoids. In 1879, Lars Fredrik Nilson and his team, found a new element with spectral analysis, in the minerals euxenite and gadolinite from Scandinavia.

Scandium is present in most of the rare earth element and uranium deposits, but it is extracted from these ores in only a few mines worldwide. Due to the low availability and the difficulties in the preparation of metallic scandium, which was first done in 1937, it took until the 1970s before applications for scandium were developed. The positive effects of scandium on aluminium alloys were discovered in the 1970s, and its use in such alloys remains its only major application.

The properties of Sc compounds are intermediate between the properties of Al and Y, and there is a diagonal relationship between the behavior of Mg and Sc, just as there is between Be and Al. There has been controversy as to whether yttrium is in the same group as lanthanum or as lutetium.[3] In the chemical compounds of the elements shown as group 3, above, the predominant oxidation state is +3. The ions M3+ will all have the electronic configuration of a noble gas, so it is reasonable that they should be in the same group of the periodic table. Most modern text-books place Sc, Y, La and Ac in the same periodic group.

 

 

Contents

[hide]

  • 1 Properties
    • 1.1 Chemical characteristics of the element
    • 1.2 Isotopes
    • 1.3 Occurrence
  • 2 Production
  • 3 Compounds
    • 3.1 Oxides and hydroxides
    • 3.2 Halides and pseudohalides
    • 3.3 Organic derivatives
    • 3.4 Compounds where scandium is not Sc3+
  • 4 History
  • 5 Applications
  • 6 Health and safety
  • 7 See also
  • 8 References
  • 9 External links

[edit] Properties

[edit] Chemical characteristics of the element

Scandium metal is hard and has a silvery appearance. It develops a slightly yellowish or pinkish cast when exposed to air. It is not resistant to weathering and dissolves slowly in most dilute acids. It does not react with a 1:1 mixture of nitric acid (HNO3) and hydrofluoric acid, HF, presumably due to the formation of an impermeable passive layer on the surface of the metal.

[edit] Isotopes

Main article: Isotopes of scandium

Scandium exists naturally as a single isotope 45Sc, which has a nuclear spin of 7/2. Thirteen radioisotopes have been characterized with the most stable being 46Sc with a half-life of 83.8 days, 47Sc with a half-life of 3.35 days, and 48Sc with a half-life of 43.7 hours. All of the remaining radioactive isotopes have half lives that are less than 4 hours, and the majority of these have half-lives that are less than 2 minutes. This element also has five meta states with the most stable being 44mSc (t½ = 58.6 h).[4]

The isotopes of scandium range in atomic weight from 40 u (40Sc) to 54 u (54Sc). The primary decay mode at masses lower than the only stable isotope, 45Sc, is electron capture, and the primary mode at masses above it is beta emission. The primary decay products at atomic weights below 45Sc are calcium isotopes and the primary products from higher atomic weights are titanium isotopes.[4]

[edit] Occurrence

Scandium does not have a particularly low abundance in the earth's crust. Estimates vary from 18 to 25 ppm, which is comparable to the abundance of cobalt (20–30 ppm). Scandium is only the 50th most common element on earth (35th most abundant in the crust, but it is the 23rd most common element in the sun).[5] However, scandium is distributed sparsely and occurs in trace amounts in many minerals.[6] Rare minerals from Scandinavia[7] and Madagascar[8] such as thortveitite, euxenite, and gadolinite are the only known concentrated sources of this element. Thortveitite can contain up to 45% of scandium in the form of scandium(III) oxide.[7]

The stable form of scandium is created in supernovas via the r-process.[9]

[edit] Production

World production of scandium is in the order of 2 tonnes per year in the form of scandium oxide. The primary production is 400 kg while the rest is from stockpiles of Russia generated during the Cold War. In 2003, only three mines produced scandium: the uranium and iron mines in Zhovti Vody in Ukraine, the rare earth mines in Bayan Obo, China and the apatite mines in the Kola peninsula, Russia. In each case scandium is a byproduct from the extraction of other elements.[10] and is sold as scandium oxide.

The production of metallic scandium is in the order of 10 kg per year.[10][11] The oxide is converted to scandium fluoride and reduced with metallic calcium.

Madagascar and Iveland-Evje region in Norway have the only deposits of minerals with high scandium content, thortveitite (Sc,Y)2(Si2O7) and kolbeckite ScPO4·2H2O, but these are not being exploited.[11] Other scandium sources include the nickel and cobalt laterite mines in Australia at Greenvale, Queensland, Syerston and Lake Innes, New South Wales, iron, tin, and tungsten deposits in China and uranium deposits in Russia and Kazakhstan. As of 2003, scandium was not being extracted from the tailings at any of these mines, but some scandium extraction may be started if there is sufficient demand.[10] There is currently no primary production of scandium in the Americas, Europe, or Australia.

The absence of reliable, secure, stable and long term production has limited commercial applications of scandium in most countries. This is despite a comprehensive body of research and a large number of patents which identify significant benefits for the use of scandium over other elements. Particularly promising are the properties of stabilizing zirconia and strengthening aluminium alloys (0.5% scandium). Scandia-stabilized zirconia has a growing market demand for use as a high efficiency electrolyte in solid oxide fuel cells. The availability of high-purity scandium oxide production is proposed to commence from the NORNICO project near Greenvale, Queensland in 2013–2014.

[edit] Compounds

The chemistry is almost completely dominated by the trivalent ion. The radii of M3+ ions in the preceding table indicate why the chemistry of scandium is more closely related to that of yttrium than that of aluminium and explains why scandium has been classified as a lanthanide-like element.

 

Ionic radii (pm)

Al Sc Y La Lu

53.5 74.5 90.0 103.2 86.1

[edit] Oxides and hydroxides

The oxide Sc2O3 is weakly acidic and the hydroxide Sc(OH)3 is amphoteric:

 

Sc(OH)3 + 3 OH− → Sc(OH)3−

6Sc(OH)3 + 3 H+ + 3 H2O → [Sc(H2O)6]3+

The α- and γ- forms of scandium oxide hydroxide (ScO(OH)), are isostructural with their aluminium oxide hydroxide counterparts.[12] Solutions of Sc3+ in water are acidic because of hydrolysis.

[edit] Halides and pseudohalides

The halides ScX3 (X = Cl, Br, I) are very soluble in water, but ScF3 is insoluble. In all four halides the scandium is 6-coordinate. The halides are Lewis acids; for example, ScF3 dissolves a solution containing excess fluoride to form [ScF6]3−. The coordination number 6 is typical of Sc(III). In the larger Y3+ and La3+ ions, 8- and 9- coordination are often found. Scandium(III) triflate is sometimes used as a Lewis acid catalyst in organic chemistry.

[edit] Organic derivatives

Main article: Organoscandium compounds

Scandium forms a series of organometallic compounds with C5Me5 ligands (Cp) such as the chlorine-bridged dimer, [ScCp2Cl]2.[13]

[edit] Compounds where scandium is not Sc3+

Compounds that feature Sc in the oxidation state other than 3 are well known. The cluster [Sc6Cl12]3− is a similar structure to that of the Nb6Cl12 cluster wherein chloride centers bridge the 12 edges of an octahedron of metal atoms.[14] The nature of the hydride ScH2 is not yet fully understood.[2] It appears not to be a saline hydride of Sc(II), but may be a compound of Sc(III) with two hydrides and an electron which is delocalized in a kind of metallic structure. ScH can be observed spectroscopically at high temperatures in the gas phase.[1] In the compounds ScB and ScC, boron and carbon are incorporated non-stoichiometrically into the lattice of the scandium.[15]

[edit] History

Dmitri Mendeleev, creator of the periodic table, predicted the existence of an element ekaboron, with an atomic mass between 40 and 48 in 1869. Ten years later Lars Fredrik Nilson found a new element in the minerals euxenite and gadolinite from Scandinavia. He was able to prepare 2 grams of scandium oxide of high purity.[16][17] He named it scandium, from the Latin Scandia meaning "Scandinavia". Nilson was apparently unaware of Mendeleev's prediction, but Per Teodor Cleve recognized the correspondence and notified Mendeleev.[18]

Metallic scandium was produced for the first time in 1937 by electrolysis of a eutectic mixture, at 700–800 °C, of potassium, lithium, and scandium chlorides.[19] The first pound of 99% pure scandium metal was produced in 1960. The use for aluminium alloys began in 1971, following a US patent.[20] Aluminium-scandium alloys were also developed in the USSR.[21]

[edit] Applications

 

 

 

 

Parts of the MiG-29 are made from Al-Sc alloy.[22]

The addition of scandium to aluminium limits the excessive grain growth that occurs in the heat-affected zone of welded aluminium components. This has two beneficial effects: the precipitated Al3Sc forms smaller crystals than are formed in other aluminium alloys[22] and the volume of precipitate-free zones that normally exist at the grain boundaries of age-hardening aluminium alloys is reduced.[22] Both of these effects increase the usefulness of the alloy. However, titanium alloys, which are similar in lightness and strength, are cheaper and much more widely used.[23]

The main application of scandium by weight is in aluminium-scandium alloys for minor aerospace industry components. These alloys contain between 0.1% and 0.5% of scandium. They were used in the Russian military aircraft, specifically the MiG-21 and MiG-29.[22]

Some items of sports equipment, which rely on high performance materials, have been made with scandium-aluminium alloys, including baseball bats[24], lacrosse sticks, as well as bicycle[25] frames and components. Lacrosse sticks are also made with scandium-titanium alloys to take advantage of the strength of titanium. The American gunmaking company Smith & Wesson produces revolvers with frames composed of scandium alloy and cylinders of titanium.[26]

Approximately 20 kg (as Sc2O3) of scandium is used annually in the United States to make high-intensity discharge lamps.[27] Scandium iodide, along with sodium iodide, when added to a modified form of mercury-vapor lamp, produces a form of metal halide lamp, an artificial light source which produce a very white light with high color rendering index that sufficiently resembles sunlight to allow good color-reproduction with TV cameras.[28] About 80 kg of scandium is used in metal halide lamps/light bulbs globally per year. The first scandium-based metal halide lamps were patented by General Electric and initially made in North America, although they are now produced in all major industrialized countries. The radioactive isotope 46Sc is used in oil refineries as a tracing agent.[27] Scandium triflate is a catalytic Lewis acid used in organic chemistry.[29]

[edit] Health and safety

Elemental scandium is not considered to be toxic. Little animal testing of scandium compounds has been done.[30] The median lethal dose (LD50) levels for scandium(III) chloride for rats have been determined and were intraperitoneal 4 mg/kg and oral 755 mg/kg.[31] In the light of these results compounds of scandium should be handled as compounds of moderate toxicity.

引用出處: 

 http://en.wikipedia.org/wiki/Scandium

歡迎來到Bewise Inc.的世界,首先恭喜您來到這接受新的資訊讓產業更有競爭力,我們是提供專業刀具製造商,應對客戶高品質的刀具需求,我們可以協助客戶滿足您對產業的不同要求,我們有能力達到非常卓越的客戶需求品質,這是現有相關技術無法比擬的,我們成功的滿足了各行各業的要求,包括:精密HSS DIN切削刀具協助客戶設計刀具流程DIN or JIS 鎢鋼切削刀具設計NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計超高硬度的切削刀具醫療配件刀具設計複合式再研磨機PCD地板專用企口鑽石組合刀具粉末造粒成型機主機版專用頂級電桿PCBN刀具PCD刀具單晶刀具PCD V-Cut捨棄式圓鋸片組粉末成型機航空機械鉸刀主機版專用頂級電汽車業刀具設計電子產業鑽石刀具木工產業鑽石刀具銑刀與切斷複合再研磨機銑刀與鑽頭複合再研磨機銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計;從微細刀具到大型刀具;從小型生產到大型量產;全自動整合;我們的技術可提供您連續生產的效能,我們整體的服務及卓越的技術,恭迎您親自體驗!!

BW Bewise Inc. Willy Chen willy@tool-tool.com  bw@tool-tool.com  www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com/ / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting toolaerospace tool .HSS  DIN Cutting toolCarbide end millsCarbide cutting toolNAS Cutting toolNAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end milldisc milling cutter,Aerospace cutting toolhss drillФрезерыCarbide drillHigh speed steelCompound SharpenerMilling cutterINDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) Core drillTapered end millsCVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden FingerPCD V-CutterPCD Wood toolsPCD Cutting toolsPCD Circular Saw BladePVDD End Millsdiamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE Single Crystal Diamond Metric end millsMiniature end millsСпециальные режущие инструменты Пустотелое сверло Pilot reamerFraisesFresas con mango PCD (Polycrystalline diamond) ‘FresePOWDER FORMING MACHINEElectronics cutterStep drillMetal cutting sawDouble margin drillGun barrelAngle milling cutterCarbide burrsCarbide tipped cutterChamfering toolIC card engraving cutterSide cutterStaple CutterPCD diamond cutter specialized in grooving floorsV-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert PCD Diamond Tool Saw Blade with Indexable InsertNAS toolDIN or JIS toolSpecial toolMetal slitting sawsShell end millsSide and face milling cuttersSide chip clearance sawsLong end millsend mill grinderdrill grindersharpenerStub roughing end millsDovetail milling cuttersCarbide slot drillsCarbide torus cuttersAngel carbide end millsCarbide torus cuttersCarbide ball-nosed slot drillsMould cutterTool manufacturer.

Bewise Inc.  www.tool-tool.com

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豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。

弊社は各領域に供給できる内容は:

(1)精密HSSエンドミルのR&D

(2)Carbide Cutting tools設計

(3)鎢鋼エンドミル設計

(4)航空エンドミル設計

(5)超高硬度エンドミル

(6)ダイヤモンドエンドミル

(7)医療用品エンドミル設計

(8)自動車部品&材料加工向けエンドミル設計

弊社の製品の供給調達機能は:

(1)生活産業~ハイテク工業までのエンドミル設計

(2)ミクロエンドミル~大型エンドミル供給

(3)小Lot生産~大量発注対応供給

(4)オートメーション整備調達

(5)スポット対応~流れ生産対応

弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。   

Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz.

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт  www.tool-tool.com  для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web  www.tool-tool.com  for more info.

 

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镉(gé,音隔),是一种化学元素,它的化学符号是Cd,它的原子序数是48,是一种蓝白色的过渡金属,性质柔软,有毒。镉能在锌矿中找到。镉和锌均会用作电池的材料。

纠错 编辑摘要

目录

  • 1 概述
  • 2 发现
  • 3 性质
  • 4 元素用途
  • 5 危害
  •  

  • 1 概述
  • 2 发现
  • 3 性质
  • 4 元素用途
  • 5 危害
    • 5.1 人体
    • 5.2 环境
    • 5.3 预防
  • 6 污染事件

 

 

镉 - 概述

镉和锌是同族之金属元素,往往与锌、铜、铅等共生,在冶炼铜、锌及镀镉工厂中均有相当量的镉单质和化合物排入大气与废水,废水中的镉排入江河沉积天水底并被生物吸收。

目 前,世界上主要生产镉的国家有美国、独联体、加拿大、日本、澳大利亚等国。美国是世界主要产镉的国家,1940年就已接近3000吨。1977年世界镉的 总产量已近两万吨。美国也是最大的镉进口国,其次是英国、法国和比利时。估计资本主义国家镉的消费量占世界总消费量的三分之二左右。

 

镉 - 发现

镉 与它的同族元素汞和锌相比,被发现的晚的多。它在地壳中含量比汞还多一些,但是汞一经出现就以强烈的金属光泽、较大的比重、特殊的流动性和能够溶解多种金 属的姿态吸引了人们的注意。镉在地壳中的含量比锌少得多,常常以少量包含于锌矿中,很少单独成矿。金属镉比锌更易挥发,因此在用高温炼锌时,它比锌更早逸 出,逃避了人们的觉察。这就注定了镉不可能先于锌而被人们发现。

 

镉 - 性质

镉,原子序数48,原子量112.411,元素名来源于拉丁文,原意是“菱锌矿”。镉是较稀有的元素,在地壳中的含量约为十万分之二。镉在自然界都以化合物形式存在,主要硫镉矿等。镉有8种天然同位素:镉106、108、110、111、112、113、114、116。

 

镉 为银白色有光泽金属,熔点320.9°C,沸点765°C,密度8.642克/厘米³。比锡稍硬,比锌软,有韧性和延展性。镉在干燥空气中很稳定,湿空气 中表面覆盖氧化膜,红热时形成褐色氧化物,燃烧时产生红色火焰;镉与卤素在高温下反应剧烈,形成卤化镉;可与硫直接化合成硫化镉;能溶于酸形成相应的盐, 但不溶于强碱。

 

镉 - 元素用途

用于电底、制造合金等;并可做成原子反应堆中的中子吸收棒。镉氧化电位高,故可用作铁、钢、铜之保护膜,广用于电镀上,并用于充电电池、电视映像管、黄色颜料及作为塑料之安定剂。镉化合物可用于杀虫剂、杀菌剂、颜料、油漆等之制造业。

 

镉 - 危害

人体

镍镉电池

镉不是人体所必需的微量元素。新生婴儿体内几乎无镉,人体中镉全部是出生后通过外界环境(例如饮水、食物、香烟)进入人体的。

研究显示,镉中毒会造成肾小管再吸收障碍,低分子量蛋白质和钙质等由尿中流失,长期下去容易形成骨质软化,关节疼痛、骨折及骨骼变形等。

 

长期摄入过量的镉,会影响体内其他有益元素的效能,造成肝肾损害、肺气肿、支气管炎、内分泌失调、食欲不振、失眠等问题。镉转移至动脉,使血压上升,引致血管脂肪化。高血压病人尿中的镉含量较正常值高出40%。另外,镉也是一种致癌物质,可能诱发前列腺癌症。

加工食物会破坏镉与锌的平衡,饮食中若锌含量不足,身体便会积存镉以取代。

环境

镉 污染土壤,可造成公害病痛痛病。镉对土壤的污染,主要通过两种形式,一是工业废气中的镉随风向四周扩散,经自然沉降,蓄积于工厂周围土壤中,另一 种方式是含镉工业废水灌溉农田,使土壤受到镉的污染。因此为了防止镉对环境的污染,必须做好环境保护工作,严格执行镉的环境卫生标准。

预防

为了预防镉中毒,熔炼、使用镉及其化合物的场所,应具有良好的通风和密闭装置。焊接和电镀工艺除应有必要的排风设备外,操作时应戴个人防毒面具。不应在生产场所进食和吸烟。中国规定的生产场所氧化镉最高容许浓度为0.1mg/m3。

 

镀镉器皿不能存放食品,特别是醋类等酸性食品。高锌食物有助排除镉。此外,高钙和高硒食物亦有排镉效力。

 

镉 - 污染事件

浏阳镉污染

1、2009年8月的湖南浏阳市镇头镇镉污染,事源长沙湘和化工厂生产次氧化锌和硫酸锌但没有完善的排污设施。截止09年8月2日,该工厂被永久关闭。

2、1930-1960件代,日本富山县神通川流域部分镉污染。事源炼锌厂排放的含镉废水污染了周围的耕地和水源。

引用出處: 

 http://www.hudong.com/wiki/%E9%95%89

歡迎來到Bewise Inc.的世界,首先恭喜您來到這接受新的資訊讓產業更有競爭力,我們是提供專業刀具製造商,應對客戶高品質的刀具需求,我們可以協助客戶滿足您對產業的不同要求,我們有能力達到非常卓越的客戶需求品質,這是現有相關技術無法比擬的,我們成功的滿足了各行各業的要求,包括:精密HSS DIN切削刀具協助客戶設計刀具流程DIN or JIS 鎢鋼切削刀具設計NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計超高硬度的切削刀具醫療配件刀具設計複合式再研磨機PCD地板專用企口鑽石組合刀具粉末造粒成型機主機版專用頂級電桿PCBN刀具PCD刀具單晶刀具PCD V-Cut捨棄式圓鋸片組粉末成型機航空機械鉸刀主機版專用頂級電汽車業刀具設計電子產業鑽石刀具木工產業鑽石刀具銑刀與切斷複合再研磨機銑刀與鑽頭複合再研磨機銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計;從微細刀具到大型刀具;從小型生產到大型量產;全自動整合;我們的技術可提供您連續生產的效能,我們整體的服務及卓越的技術,恭迎您親自體驗!!

BW Bewise Inc. Willy Chen willy@tool-tool.com  bw@tool-tool.com  www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com/ / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting toolaerospace tool .HSS  DIN Cutting toolCarbide end millsCarbide cutting toolNAS Cutting toolNAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end milldisc milling cutter,Aerospace cutting toolhss drillФрезерыCarbide drillHigh speed steelCompound SharpenerMilling cutterINDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) Core drillTapered end millsCVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden FingerPCD V-CutterPCD Wood toolsPCD Cutting toolsPCD Circular Saw BladePVDD End Millsdiamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE Single Crystal Diamond Metric end millsMiniature end millsСпециальные режущие инструменты Пустотелое сверло Pilot reamerFraisesFresas con mango PCD (Polycrystalline diamond) ‘FresePOWDER FORMING MACHINEElectronics cutterStep drillMetal cutting sawDouble margin drillGun barrelAngle milling cutterCarbide burrsCarbide tipped cutterChamfering toolIC card engraving cutterSide cutterStaple CutterPCD diamond cutter specialized in grooving floorsV-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert PCD Diamond Tool Saw Blade with Indexable InsertNAS toolDIN or JIS toolSpecial toolMetal slitting sawsShell end millsSide and face milling cuttersSide chip clearance sawsLong end millsend mill grinderdrill grindersharpenerStub roughing end millsDovetail milling cuttersCarbide slot drillsCarbide torus cuttersAngel carbide end millsCarbide torus cuttersCarbide ball-nosed slot drillsMould cutterTool manufacturer.

Bewise Inc.  www.tool-tool.com

ようこそBewise Inc.の世界へお越し下さいませ、先ず御目出度たいのは新たな

情報を受け取って頂き、もっと各産業に競争力プラス展開。

弊社は専門なエンドミルの製造メーカーで、客先に色んな分野のニーズ

豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。

弊社は各領域に供給できる内容は:

(1)精密HSSエンドミルのR&D

(2)Carbide Cutting tools設計

(3)鎢鋼エンドミル設計

(4)航空エンドミル設計

(5)超高硬度エンドミル

(6)ダイヤモンドエンドミル

(7)医療用品エンドミル設計

(8)自動車部品&材料加工向けエンドミル設計

弊社の製品の供給調達機能は:

(1)生活産業~ハイテク工業までのエンドミル設計

(2)ミクロエンドミル~大型エンドミル供給

(3)小Lot生産~大量発注対応供給

(4)オートメーション整備調達

(5)スポット対応~流れ生産対応

弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。   

Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz.

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт  www.tool-tool.com  для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web  www.tool-tool.com  for more info.

 

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Cadmium ( /ˈkædmiəm/ KAD-mee-əm) is a chemical element with the symbol Cd and atomic number 48. The soft, bluish-white metal is chemically similar to the two other metals in group 12, zinc and mercury. Similar to zinc it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low melting point compared to transition metals. Cadmium and its congeners are not considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states.[2] Average concentration in the earth’s crust is between 0.1 and 0.5 parts per million (ppm). It was discovered simultaneously by Stromeyer and Hermann, both in Germany, as an impurity in zinc carbonate.[3]

Cadmium occurs as a minor component in most zinc ores and therefore is a byproduct of zinc production. Cadmium was used for a long time as a pigment and for corrosion resistant plating on steel. Cadmium compounds were used to stabilize plastic. With the exception of its use in nickel-cadmium batteries and cadmium telluride solar panels, the use of cadmium is generally decreasing in its other applications. These declines have been due to competing technologies, cadmium’s toxicity in certain forms and concentration and resulting regulations.[4] Although cadmium is toxic, one enzyme, a carbonic anhydrase with cadmium as reactive center has been discovered.

 

 

Contents

[hide]

  • 1 Characteristics
    • 1.1 Physical properties
    • 1.2 Chemical properties
    • 1.3 Isotopes
  • 2 History
  • 3 Occurrence
  • 4 Extraction
  • 5 Applications
    • 5.1 Batteries
    • 5.2 Other uses
    • 5.3 Historic uses
  • 6 Biological role
    • 6.1 Neurological role
  • 7 Toxicity
  • 8 Product recalls
    • 8.1 Highbury Seats
    • 8.2 Jewelry
    • 8.3 McDonald's drinking glasses
  • 9 See also
  • 10 References
  • 11 External links

[edit] Characteristics

[edit] Physical properties

Cadmium is a soft, malleable, ductile, bluish-white bivalent metal. It is similar in many respects to zinc but forms complex compounds.[5]

[edit] Chemical properties

 

See also Category: Cadmium compounds

The most common oxidation state of cadmium is +2, though rare examples of +1 can be found. Cadmium burns in air to form brown amorphous cadmium oxide (CdO). The crystalline form of the same compound is dark red and changes color when heated, similar to zinc oxide. Hydrochloric acid, sulfuric acid and nitric acid dissolve cadmium by forming cadmium chloride (CdCl2) cadmium sulfate (CdSO4) or cadmium nitrate (Cd(NO3)2). The oxidation state +1 can be reached by dissolving cadmium in a mixture of cadmium chloride and aluminium chloride, forming the Cd22+ cation, which is similar to the Hg22+ cation in mercury(I) chloride.[5]

 

Cd + CdCl2 + 2 AlCl3 → Cd2[AlCl4]2

[edit] Isotopes

 

 

 

 

The cadmium-113 total cross section clearly showing the cadmium cutoff.

Main article: Isotopes of cadmium

Naturally occurring cadmium is composed of 8 isotopes. For two of them, natural radioactivity was observed, and three others are predicted to be radioactive but their decay is not observed, due to extremely long half-life times. The two natural radioactive isotopes are 113Cd (beta decay, half-life is 7.7 × 1015 years) and 116Cd (two-neutrino double beta decay, half-life is 2.9 × 1019 years). The other three are 106Cd, 108Cd (double electron capture), and 114Cd (double beta decay); only lower limits on their half-life times have been set. At least three isotopes - 110Cd, 111Cd, and 112Cd - are stable. Among the isotopes absent in natural cadmium, the most long-lived are 109Cd with a half-life of 462.6 days, and 115Cd with a half-life of 53.46 hours. All of the remaining radioactive isotopes have half-lives that are less than 2.5 hours, and the majority of these have half-lives that are less than 5 minutes. This element also has 8 known meta states, with the most stable being 113mCd (t½ = 14.1 years), 115mCd (t½ = 44.6 days), and 117mCd (t½ = 3.36 hours).

The known isotopes of cadmium range in atomic mass from 94.950 u (95Cd) to 131.946 u (132Cd). For isotopes lighter than 112 u, the primary decay mode is electron capture and the dominant decay product is element 47 (silver). Heavier isotopes decay mostly through beta emission producing element 49 (indium).

One isotope of cadmium, 113Cd, absorbs neutrons with very high probability if they have an energy below the cadmium cut-off and transmits them readily otherwise. The cadmium cut-off is about 0.5 eV.[6] Neutrons with energy below the cutoff are deemed slow neutrons, distinguishing them from intermediate and fast neutrons.

Cadmium is created via the long S-process in low-medium mass stars (.6 -> 10 solar masses), lasting thousands of years to do. It requires a silver atom to capture a neutron and then undergo beta decay.[citation needed]

[edit] History

 

 

 

 

Friedrich Stromeyer

Cadmium (Latin cadmia, Greek καδμεία meaning "calamine", a cadmium-bearing mixture of minerals, which was named after the Greek mythological character, Κάδμος Cadmus, the founder of Thebes) was discovered simultaneously by Friedrich Stromeyer[7] and Karl Samuel Leberecht Hermann, both in Germany, as an impurity in zinc carbonate.[4] Stromeyer found the new element as an impurity in zinc carbonate (calamine), and, for 100 years, Germany remained the only important producer of the metal. The metal was named after the Latin word for calamine, since the metal was found in this zinc compound. Stromeyer noted that some impure samples of calamine changed color when heated but pure calamine did not. He was persistent in studying these results and eventually isolated cadmium metal by roasting and reduction of the sulfide. Even though cadmium and its compounds may be toxic in certain forms and concentrations, the British Pharmaceutical Codex from 1907 states that cadmium iodide was used as a medication to treat "enlarged joints, scrofulous glands,[8] and chilblains".

In 1927, the International Conference on Weights and Measures redefined the meter in terms of a red cadmium spectral line (1 m = 1,553,164.13 wavelengths).[9] This definition has since been changed (see krypton).

After the industrial scale production of cadmium started in the 1930s and 1940s the major application was the coating of iron and steel to prevent corrosion.[4] In 1944, 62% and in 1956 59% of the cadmium in the United States was used for this purpose.[10] The second application was red, orange and yellow pigments based on sulfides and selenides of cadmium. In 1956, 24% of the cadmium used within the United States was used for this purpose.[10] The stabilizing effect of cadmium-containing chemicals (carboxylates such as the laureate and the stearate) on PVC led to a increased use of those compounds in the 1970s and 1980s. The use of cadmium in applications such as pigments, coatings, stabilizers and alloys declined due to environmental and health regulations in the 1980s and 1990s. In 2006, only 7% of total cadmium consumption was used for plating and coating and only 10% was used for pigments.[4] The decrease in consumption in other applications was made up by a growing demand of cadmium in nickel-cadmium batteries, which accounted for 81% of the cadmium consumption in the United States in 2006.[11]

[edit] Occurrence

 

 

 

 

Cadmium metal

 

See also Category: Cadmium minerals

Cadmium-containing ores are rare and are found to occur in small quantities. However, traces do naturally occur in phosphate, and have been shown to transmit in food through fertilizer application.[12] Greenockite (CdS), the only cadmium mineral of importance, is nearly always associated with sphalerite (ZnS). As a consequence, cadmium is produced mainly as a byproduct from mining, smelting, and refining sulfidic ores of zinc, and, to a lesser degree, lead and copper. Small amounts of cadmium, about 10% of consumption, are produced from secondary sources, mainly from dust generated by recycling iron and steel scrap. Production in the United States began in 1907, but it was not until after World War I that cadmium came into wide use.[13][14]

One place where metallic cadmium can be found is the Vilyuy River basin in Siberia.[15]

[edit] Extraction

 

 

 

 

World production trend

 

 

 

 

Cadmium output in 2005

In 2001, China was the top producer of cadmium with almost one-sixth world share closely followed by South Korea and Japan, reports the British Geological Survey.[16]

Cadmium is a common impurity in zinc ores, and it is most often isolated during the production of zinc. Some zinc ores concentrates from sulfidic zinc ores contain up to 1.4% of cadmium.[17] In 1970s, the output of cadmium was 6.5 pounds per ton of zinc.[17] Zinc sulfide ores are roasted in the presence of oxygen, converting the zinc sulfide to the oxide. Zinc metal is produced either by smelting the oxide with carbon or by electrolysis in sulfuric acid. Cadmium is isolated from the zinc metal by vacuum distillation if the zinc is smelted, or cadmium sulfate is precipitated out of the electrolysis solution.[14][18]

[edit] Applications

[edit] Batteries

 

 

 

 

Ni-Cd batteries

In 2009, 86% of all the cadmium is used in batteries, predominantly in rechargeable nickel-cadmium batteries. Nickel-cadmium cells have a nominal cell potential of 1.2 V. The cell consists of a positive nickel hydroxide electrode and a negative cadmium electrode plate separated by an alkaline electrolyte (potassium hydroxide). The European Union banned the use of cadmium in electronics in 2004 with several exceptions but reduced the allowed content of cadmium in electronics to 0.002%.[19]

[edit] Other uses

 

 

 

 

Violet light from a helium cadmium metal vapor laser. The highly monochromatic color arises from the 441.563 nm transition line of cadmium.

 

 

 

 

Train painted with cadmium orange

 

 

 

 

A photograph and representative spectrum of photoluminescence from colloidal CdSe quantum dots.

Most of cadmium which is not consumed in battery production is used mainly for cadmium pigments, coatings and plating. Examples of some uses include:

  • In electroplating (6% cadmium).[20] Cadmium electroplating is widely used in aircraft industry due to the excellent corrosion resistance of cadmium-plated steel components. The coating is usually passivated by chromate salts.[citation needed]
  • Helium-cadmium lasers are a popular source of blue-ultraviolet laser light. They operate either at 325 or 422 nm and are used in fluorescence microscopes and various laboratory experiment.[21]
  • Cadmium is used as a barrier to control neutrons in nuclear fission.[20]
  • The pressurized water reactor designed by Westinghouse Electric Company uses an alloy consisting of 80% silver, 15% indium, and 5% cadmium.[20]
  • Cadmium oxide in black and white television phosphors and in the blue and green phosphors for color television picture tubes.[22]
  • Cadmium sulfide (CdS) as a photoconductive surface coating for photocopier drums.[23]
  • In paint pigments, cadmium forms various salts, with CdS being the most common. This sulfide is used as a yellow pigment. Cadmium selenide can be used as red pigment, commonly called cadmium red. To painters who work with the pigment, cadmium yellows, oranges, and reds are the most brilliant and long-lasting colors to use. In fact, during production, these colors are significantly toned down before they are ground with oils and binders, or blended into watercolors, gouaches, acrylics, and other paint and pigment formulations. Since these pigments are potentially toxic, it is recommended to use a barrier cream on the hands to prevent absorption through the skin when working with them[24] even though the amount of cadmium absorbed into the body through the skin is usually reported to be less than 1%.[citation needed]
  • Cadmium selenide quantum dots emit bright luminescence under UV excitation (He-Cd laser, for example). The color of this luminescence can be green, yellow or red depending on the particle size. Colloidal solutions of those particles are used for imaging of biological tissues and solutions with a fluorescence microscope.[25]
  • Cadmium is a component of some compound semiconductors, such as cadmium sulfide, cadmium selenide, and cadmium telluride, which can be used for light detection or solar cells. HgCdTe is sensitive to infrared[20] light and therefore may be utilized as an infrared detector or switch for example in remote control devices.
  • In PVC as heat, light, and weathering stabilizers[20][26] although cadmium stabilizers have now been almost completely replaced with barium-zinc, calcium-zinc and organo-tin stabilizers.
  • In molecular biology, cadmium is used to block voltage-dependent calcium channels from fluxing calcium ions, as well as in hypoxia research to stimulate proteasome-dependent degradation of Hif-1α.[27]

[edit] Historic uses

  • In many kinds of solder.[20]
  • In bearing alloys, due to a low coefficient of friction and very good fatigue resistance.[20]
  • In some of the lowest-melting alloys, such as Wood's metal.[28]

[edit] Biological role

Cadmium has no known useful role in higher organisms.[29] A role for cadmium in lower lifeforms has recently been found. A cadmium-dependent carbonic anhydrase has been found in marine diatoms. Cadmium performs the same function as zinc in other anhydrases, but the diatoms live in environments with very low zinc concentrations and thus the biological system has utilized cadmium in place of zinc to perform that function normally carried out by zinc. The discovery was made using X-ray absorption fluorescence spectroscopy (XAFS), and cadmium was characterized by noting the energy of the X-rays that were absorbed.[30]

The highest concentration of cadmium has been found to be absorbed in the kidneys of humans, and up to about 30 mg of cadmium is commonly inhaled throughout childhood and adolescence. [31][32]

[edit] Neurological role

Cadmium can be used to block calcium channels in chicken neurons. (source:"Calcium channel block by cadmium in chicken sensory neurons" -- PNAS March 1, 1989 vol. 86 no. 5 1736-1740)

[edit] Toxicity

Main article: Cadmium poisoning

 

 

 

 

WHO international poison warning symbol

The most dangerous form of occupational exposure to cadmium is inhalation of fine dust and fumes, or ingestion of highly soluble cadmium compounds.[4] Inhalation of cadmium-containing fumes can result initially in metal fume fever but may progress to chemical pneumonitis, pulmonary edema, and death.[33]

Cadmium is also a potential environmental hazard. Human exposures to environmental cadmium are primarily the result of fossil fuel combustion, phosphate fertilizers, natural sources, iron and steel production, cement production and related activities, nonferrous metals production, and municipal solid waste incineration.[4] However, there have been a few instances of general population toxicity as the result of long-term exposure to cadmium in contaminated food and water. In the decades leading up to World War II, Japanese mining operations contaminated the Jinzū River with cadmium and traces of other toxic metals. As a consequence, cadmium accumulated in the rice crops growing along the riverbanks downstream of the mines. Some members of the local agricultural communities consuming the contaminated rice developed itai-itai disease and renal abnormalities, including proteinuria and glucosuria.[34] The victims of this poisoning were almost exclusively post-menopausal women with low iron and other mineral body stores. Similar general population cadmium exposures in other parts of the world have not resulted in the same health problems as long as the populations maintained sufficient iron and other mineral levels. Thus, while cadmium is a major factor in the Itai Itai disease in Japan, most researchers have concluded that it was one of several factors.[4] Cadmium is one of six substances banned by the European Union's Restriction on Hazardous Substances (RoHS) directive, which bans certain hazardous substances in electrical and electronic equipment but allows for certain exemptions and exclusions from the scope of the law.[35]

There has been research linking exposure to cadmium to lung and prostate cancer. However, there is still a substantial controversy about the carcinogenicity of cadmium in the scientific community. More recent studies suggest that arsenic rather than cadmium may lead to the increased lung cancer mortality rates. Furthermore, most data regarding the carcinogenicity of cadmium rely on research confounded by the presence of other carcinogenic substances.[4]

Tobacco smoking is the most important single source of cadmium exposure in the general population. It has been estimated that about 10% of the cadmium content of a cigarette is inhaled through smoking. The absorption of cadmium from the lungs is much more effective than that from the gut, and as much as 50% of the cadmium inhaled via cigarette smoke may be absorbed.[36]

On average, smokers have 4-5 times higher blood cadmium concentrations and 2-3 times higher kidney cadmium concentrations than non-smokers. Despite the high cadmium content in cigarette smoke, there seems to be little exposure to cadmium from passive smoking. No significant effect on blood cadmium concentrations could be detected in children exposed to environmental tobacco smoke.[37]

[edit] Product recalls

[edit] Highbury Seats

In May 2006, a sale of the seats from Arsenal F.C.'s old stadium, Highbury in London, England was cancelled after the seats were discovered to contain trace amounts of cadmium.[38]

[edit] Jewelry

Reports of high levels of cadmium use in children's jewelry in 2010 led to a US Consumer Product Safety Commission investigation. Twelve percent of the 103 items tested from New York, Ohio, Texas and California contained at least 10 percent cadmium, with a single item test claimed to be 91 percent cadmium.[39] The CPSC issued specific recall notices for cadmium content applying to jewelry sold by Claire's[40] and Wal-Mart[41] stores.

[edit] McDonald's drinking glasses

In June 2010 McDonald's voluntarily recalled more than 12 million promotional “Shrek Forever After 3D” Collectable Drinking Glasses due to concerns over cadmium levels in paint pigments used on the glassware.[42] The glasses were manufactured by ARC International, of Millville, NJ.[

 

引用出處: 

 http://en.wikipedia.org/wiki/Cadmium

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铟是银白色并 略带淡蓝色的金属 ,熔点156.61℃,沸点2080℃,密度7.3克/厘米3(20℃)。很软,能用指甲刻痕,比铅的硬度还低。铟的可塑性强,有延展性,可压成极薄的金 属片。从常温到熔点之间,铟与空气中的氧作用缓慢,表面形成极薄的氧化膜,温度更高时,与氧、卤素、硫、硒、碲、磷作用。大块金属铟不与沸水和碱反应,但 粉末状的铟可与水作用,生成氢氧化铟。铟与冷的稀酸作用缓慢,易溶于浓热的无机酸和乙酸、草酸。铟能与许多金属形成合金。铟的氧化态为+1和+3,主要化 合物有In2O3、In(OH)3,与卤素化合时,能形成一卤化物和三卤化物。

纠错 编辑摘要

目录

  • 1 汉字铟
  • 2 词典释义
  • 3 金属铟概述
  • 4 综合性质
  • 5 特性
  •  

  • 1 汉字铟
  • 2 词典释义
  • 3 金属铟概述
    • 3.1 简介
    • 3.2 发现及用途
    • 3.3 存在
    • 3.4 资源
  • 4 综合性质
    • 4.1 物理性质
    • 4.2 化学性质
  • 5 特性
  • 6 发现
  • 7 用途
  • 8 产地
  • 9 危险性
  • 10 提取工艺
  • 11 工业生产中提取铟的方法
  • 12 应用领域
  • 13 中国铟价面临“有市无价”
  • 14 投资前景
  • 15 字源字形

 

铟 - 汉字铟

繁体字:銦

拼音:yīn  

注音:ㄧㄣ

简体部首:钅,部外笔画:6,总笔画:11

繁体部首:金

五笔86&98:QLDY

仓颉:OPWK

郑码:PJD

笔顺编号:31115251341

四角号码:86700

UniCode:CJK 统一汉字 U+94DF铟 繁体字:銦 添至备忘录

拼音:yīn   注音:ㄧㄣ

简体部首:钅,部外笔画:6,总笔画:11

繁体部首:金

五笔86&98:QLDY  仓颉:OPWK  郑码:PJD

笔顺编号:31115251341  四角号码:86700  UniCode:CJK 统一汉字 U+94DF[1]

 

铟 - 词典释义

基本字义

● 铟

(銦)

yīn  ㄧㄣˉ

◎ 一种金属元素,质软,能拉成细丝。可作低熔合金、轴承合金、半导体、电光源等的原料。

详细字义

◎ 铟

銦 yīn

〈名〉

一种软的有延展性的易熔银白色金属元素,原子序数49,不易失去光泽,与铝和镓类似,主要是三价,在闪锌矿和其他矿石中有很小量存在,主要作飞机用的涂敷铅的银轴承的镀层 [indium]——元素符号In

 

铟 - 金属铟概述

简介

铟 (英文:indium),元素符号In,原子序数49,原子量114.82,属周期系ⅢA族。铟是一种柔软的银灰色金属,带有光泽。从常温到熔点之间, 铟与空气中的氧作用缓慢,表面形成极薄的氧化膜,温度更高时,与氧、卤素、硫、硒、碲、磷作用。大块金属铟不与沸水和碱反应,但粉末状的铟可与水作用,生 成氢氧化铟。铟与冷的稀酸作用缓慢,易溶于浓热的无机酸和乙酸、草酸。铟能与许多金属形成合金。铟的氧化态为+1和+3,主要化合物有In2O3、 In(OH)3,与卤素化合时,能形成一卤化物和三卤化物。铟-115是最常见的铟同位素,带有微弱的放射性。

发现及用途

 1863 年F.赖希和H.T.里希特为了寻找铊而研究闪锌矿,用处理矿物所得的硫化物进行光谱分析,发现一条靛蓝色光谱,认为是一种新元素,并命名为 铟,意思是“靛蓝色”,同年分离出金属铟。铟主要作为包复层或与其它金属制成合金,以增强耐腐蚀性;铟有优良的反射性,可用来制造反射镜;铟合金可作反应 堆控制棒;在无线电和半导体技术中,铟及铟的化合物也有重要用途。铟可用作低熔点合金、半导体、整流器、热敏电阻等。含24%铟及76%镓的合金,在室温 下是液体。铟是电子、电信、光电产业不可或缺的关键原材料之一,70%的铟用于制造液晶显示产品,在电子、电信、光电、国防、通讯等领域具有广泛用途,极 具战略地位。铟产业被称为“信息时代的朝阳产业”。

存在

铟在地壳中的含量为 1×10-5%,它虽然也有独立矿物 ,硫铟铜矿(CuInS2)、硫铟铁矿(FeInS4)、水铟矿[In(OH)3],但量极少, 绝大部分铟都分散在其他矿物中,主要是含硫的铅、锌矿物,闪锌矿中铟的含量为0.0001%~0.1%,铅锌冶炼厂和锡冶炼厂都能回收铟。

资源

铟 是非常稀少的金属,全世界铟的地质含量仅为1.6万吨,为黄金地质储量的1/6。铟在地壳中的含量约十万分之一,没有独立矿物,广泛分布于闪锌矿中,含 量在0.1%以下。铟矿物多伴生在有色金属硫化矿物中,特别是硫化锌矿,其次是方铅矿、氧化铅矿、锡矿、硫化铜矿和硫化锑矿等。虽然在一些有色金属精矿中 铟得到初步富集,但由于铟品位低,一般不可直接作为提铟原料。而上述有色金属精矿经过冶炼或高炉炼铁后得到的粗锌、粗铅、炉渣、浸出渣、溶液、烟尘、合 金、阳极泥等是提铟的主要原料。中国拥有世界上最大的铟储量,也是全球最大的铟生产国和出口国,产量占世界铟总产量的30%以上。2006年,中国精铟产 量近6吨,原生铟供应量占全球的60%以上。日本是世界上最大的铟消费国,每年铟需求量占世界铟年产量的70%以上,绝大部分从中国进口。

 

铟 - 综合性质

物理性质

颜色和状态:银白色金属

声音在其中的传播速率(m/S):1215

密度:7.31克/厘米3

熔点:156.61℃

沸点:2080℃

莫氏硬度:1.2

电离能 (kJ /mol) : 5.786电子伏特

M - M+ 558.3

M+ - M2+ 1820.6

M2+ - M3+ 2704

M3+ - M4+ 5200

M4+ - M5+ 7400

M5+ - M6+ 9500

M6+ - M7+ 11700

M7+ - M8+ 13900

M8+ - M9+ 17200

M9+ - M10+ 19700

其它:稀散元素之一,有延展性,比铝软。  

化学性质

元素原子量:114.8

元素类型:金属

原子体积(立方厘米/摩尔):15.7

原子序数:49

元素符号:In

相对原子质量:114.8

核内质子数:49

核外电子数:49

核电荷数:49

氧化态:

主要:In+3

其它:In+1, In+2

质子质量:8.1977E-26

质子相对质量:49.343

所属周期:5

所属族数:IIIA

摩尔质量:115g/mol

外围电子排布:5s2 5p1

核外电子排布:2,8,18,18,3

晶体结构:晶胞为四方晶胞。  

    晶胞参数:

a = 325.23 pm

b = 325.23 pm

c = 494.61 pm

α = 90°

β = 90°

γ = 90°

原子半径:2

其它:易溶于酸或碱;不能分解水;在空气中很稳定;燃烧时会发生鲜紫色的火焰。

 

铟 - 特性

其一:铟金属显银白略带淡蓝色,光泽亮丽,在弯曲时会发出鸣音。其与铜银金的合金制作假牙。熔点156.61°C,沸点2080°C,密度7.3克/厘米³;延展性好,比铅还软。

其 二:铟具有熔点低(156.61°C),沸点高 (2080°C),传导性好,延展性好,比铅还软,能用指甲刻痕;可塑性强,可压成极薄的金属片。其氧化物能形成透明的导电膜等特性,近年在铟锡氧化物 (ITO)、半导体、低熔点合金等方面得到广泛应用。特别是由于铟锡氧化物(ITO)具有可见光透过率95%以上、紫外线吸收率≥70%、对微波衰减率 ≥85%、导电和加工性能良好、膜层既耐磨又耐化学腐蚀等优点,作为透明导电膜已获得广泛应用。随着IT产业的迅猛发展,用于笔记本电脑、电视和手机等各 种新型液晶显示器(LCD)以及接触式屏幕、建筑用玻璃等方面,作为透明电极涂层的ITO靶材(约占铟用量的70%)用量的急剧增长,使铟的需求正以年均 30%以上的增长率递增。世界市场上平面显示器的快速增长成为全世界铟的生产的最主要的最终用户,包括平面电视、台式计算机显示器、可上网的笔记本电脑、 手机等主要的平面显示器的快速发展和应用,使得国际市场对铟的需求急剧增长,而且目前还没有新的用于替代ITO的材料研究出来。

其三、从常 温到熔点之间,铟与空气中的氧作用缓慢,表面形成极薄的氧化膜,温度更高时,与氧、卤素、硫、硒、碲、磷作用。铟在空气中的氧化作用很慢;大块金属铟不与 沸水和碱反应,但粉末状的铟可与水作用,生成氢氧化铟。铟与冷的稀酸作用缓慢,易溶于浓热的无机酸和乙酸、草酸。 铟可作为包复层或与其它金属制成合金,以增强发动机轴承耐腐蚀性;铟有优良的反射性,可用来制造反射镜;银铅铟合金可作高速航空发动机的轴承材料。易熔的 伍德合金中每加1%铟,可降低熔点1.45℃。铟化合物半导体有锑化铟(通迅激光光源、太阳能电池),磷化铟和锑化铟(红外检测、光磁器件、太阳能转换器 等)。 

其四:铟合金可作反应堆控制棒,能够敏感地检测中子幅射;可用于登陆舱,着陆时不脆化、不开裂。 

 

铟 - 发现

1863年,德国的赖希和李希特,用光谱法研究闪锌矿,发现有新元素,即铟。

铊 被发现和取得后,德国弗赖贝格(Freiberg)矿业学院物理学教授赖希由于对铊的一些性质感兴趣,希望得到足够的金属进行实验研究。他在 1863年开始在夫赖堡希曼尔斯夫斯特(Himmelsfüst)出产的锌矿中寻找这种金属。这种矿石所含主要成分是含砷的黄铁矿、闪锌矿、辉铅矿、硅 土、锰、铜和少量的锡、镉等。赖希认为其中还可能含有铊。虽然实验花费了很多时间,他却没有获得期望的元素。但是他得到了一种不知成分的草黄色沉淀物。他 认为是一种新元素的硫化物。

只有利用光谱进行分析来证明这一假设。可是赖希是色盲,只得请求他的助手H.T.李希特进行光谱分析实验。李 希特在第一次实验就成功了,他在分光镜中 发现一条靛蓝色的明线,位置和铯的两条蓝色明亮线不相吻合,就从希腊文中“靛蓝”(indikon)一词命名它为indium(铟)(In)。两位科学家 共同署名发现铟的报告。分离出金属铟的还是他们两人共同完成的。他们首先分离出铟的氯化物和氢氧化物,利用吹管在木炭上还原成金属铟,于1867年在法国 科学院展出。

铟在地壳中的分布量比较小,又很分散。它的富矿还没有发现过,只是在锌和其他一些金属矿中作为杂质存在,因此它被列入稀有金属。

 

铟 - 用途

铟锭因其光渗透性和导电性强,主要用于生产ITO 靶材(用于生产液晶显示器和平板屏幕),这一用途是铟锭的主要消费领域,占全球铟消费量的70%。

其次的几个消费领域分别是:电子半导体领域,占全球消费量的12%;焊料和合金领域占12%;研究行业占6%。另,因为其较软的性质在某些需填充金

属的行业上也用于压缝。如:较高温度下的真空缝隙填充材料。

医学:肝、脾、骨髓扫描用铟胶体。脑、肾扫描用铟-DTPA。肺扫描用铟Fe(OH)**3颗粒。 胎盘扫描用铟Fe抗坏血酸。 肝血池扫描用铟输铁蛋白。

 

铟 - 产地

中国是世界上铟锭主要生产地,此外全球还有美国、加拿大及日本等国生产。

我国的铟分布在铅锌矿床和铜多金属矿床中,保有储量为13014t,分布15 个省区,主要集中在云南(占全国铟总储量的40%)、广西(31.4%)、内蒙古(8.2%)、青海(7.8%)、广东(7%)。

尚未发现铟的单独矿床,它以微量伴生在锌、锡等矿物中。当其含量达十万分之几,就有工业生产价值,目前主要是从闪锌矿中提取。另外,从锌、铅和锡生产的废渣、烟尘中也可回收铟。

 

铟 - 危险性

重金属,有轻微毒性。

健康危害:

铟 比铅还毒。美国和英国已公布了铟的职业接触限值均为0.1 mg/m3[11]。而这两个国家铅的标准为0.15 mg/m3。说明铟的毒性不可轻 视。液晶显示器含有铟,据新华社消息,28岁的黄力(化名)就职于江苏一家生产手机液晶显示屏的企业,主要工作是将一些金属粉喷在液晶屏幕模板上.工作两 年后,他经常呼吸困难、 喘不过气来,检查发现肺部布满雪花状的白色颗粒物.经过半年多时间的医学循征,呼吸科专家认为,黄力是罕见的铟中毒,他血液里的 铟是常规的300倍。黄力肺里的粉尘颗粒无法抽出,所以肺部功能很难恢复,而且还在不断地自我排出蛋白质。所以每隔一个月就要到医院进行一次全肺灌洗,否 则就可能旧病复发,有生命危险。

环境危害: 对环境有危害,对水体可造成污染。

燃爆危险: 可燃,具刺激性。

 

铟 - 提取工艺

 铟的提取工艺以萃取-电解法为主,这也是现今世界上铟生产的主流工艺技术。其原则工艺流程是:含铟原料→富集→化学溶解→净化→萃取→反萃取→锌(铝)置换→海绵铟→电解精炼→精铟。

铟 多数与其性质类似的锌、 铅、铜和锡等共生,现已发现有自然铟、硫铟铁矿(FeIn2S4)、硫铟铜矿(CuInS2)、硫铜锌铟矿[(Cu,Zn,Fe)3(In,Sn)S4] 和羟铟矿[In(OH)3]等5种含铟矿物。铟在硫化矿中的含量最高,闪锌矿是主要工业来源,铜矿、方铅矿、黄锡矿与锡石也含有较高的铟,但由于产量极 少,非常分散,不能作为直接生产铟的原料,一般是从锌、铅、锡等重金属冶炼的副产物中回收生产。由于稀散金属离子在化学性质上有许多相似之处,造成分离、 富集、回收上的困难,近年来,随着铟需求量不断增加,对于铟的富集、回收进行了很多的研究。

世界上铟产量的90% 来自铅锌冶炼厂的副产 物。铟的冶炼回收方法主要是从铜、 铅、锌的冶炼浮渣、熔渣及阳极泥中通过富集加以回收。根据回收原料的来源及含铟量的差别,应用不同的提取工艺,达到最佳配置和最大收益。常用的工艺技术有 氧化造渣、金属置换、电解富集、酸浸萃取、萃取电解、离子交换、电解精炼等。当前较为广泛应用的是溶剂萃取法,它是一种高效分离提取工艺。离子交换法用于 铟的回收,还未见工业化的报导。在从较难挥发的锡和铜内分离铟的过程中,铟多数集中在烟道灰和浮渣内。在挥发性的锌和镉中分离时,铟则富集于炉渣及滤渣 内。

 

在ISP炼铅锌工艺中,精矿中的铟较大部分富集于粗锌精馏工序产出的粗铅中,回收富铟粗铅的铟,一直采用碱煮提铟工艺,存在生产能力小、生产成本高、金属回收率低等缺点。

为 了简化铟的提取流程,降低生产成本,提高金属回收率,针对原有的提铟生产工艺,本项目通过条件试验、循环实验及综合试验,研究开发了“富铟粗铅电 解-铅电解液萃铟”提取工艺,确定了新工艺的最佳工艺参数。工艺流程为:粗铅熔化铸成极板,装入电解槽通电进行电解,阳极中的铟溶解进入电解液,当铟富集 到一定浓度后,抽出电解液进行萃取、反萃,富铟反萃液经pH调节、置换、压团熔铸后得到粗铟。[2]

 

铟 - 工业生产中提取铟的方法

 

1、从炼锌副产品中回收铟

日 本同和矿业公司以炼锌中产生的净液残渣作为原料,先分离和浸出,脱铜、脱铝,除去原料中与镓铟性质相似的重金 属,然后在富集镓铟的溶液中加入盐酸,混合搅拌,调整酸度之后,再用醚萃取铟,使它和镓及其它金属分离。最后用水反萃出铟,再经置换,熔融和电解。 在每 次电解中需调整电流密度和电解液的酸度,以除去微量的镉、 锡和铝等,生产出4 N 以上的金属铟。此外,铟的选择性分离法是把铅、锌冶炼过程中产生的含有微量的铟烟尘、阳极泥等各种残渣以及电解排出液作为原料, 采用含萃取剂膦酸二(2-乙基己基)酯的有机溶剂,于pH小于1.0的条件下,对含铟及其它金属的硫酸溶液萃取,然后用盐酸在30-700C 进行反萃, 从而选择性分离铟。其萃取铟的效率可高达98%以上。

 

2、硬锌真空蒸馏提锌和富集锗铟银

“硬锌真空蒸馏提 锌和富集锗铟银”项目属于材料学科,冶金技术领域科研项目。硬锌是粗锌火法精馏过程中 产出的一种中间产物,是由粗锌中的高沸点物质组成,其主要是以锌铅铁砷为主体并含有锗铟银等元素的多元合金。硬锌的产出率约占粗锌处理量的4%。由昆明理 工大学中国工程院院士戴永年等人主持研究的“硬锌真空蒸馏提锌和富集锗铟银”项目获得了2003年度国家技术发明奖二等奖。

该技术用“真 空蒸馏法提锌和富集锗铟银”的新流程及新工艺,并成功地研制了与该工艺流程配套的生产设备,突破了常规的在现有生产技术上进行技术改造 的传统做法,取得了成功。有关专家评价道,该发明工艺属国内首创,且安全可靠,操作方便,无“三废”污染,属“绿色冶金”新技术,符合国家所倡导的资源综 合利用的可持续发展战略,具有新颖性、创造性和实用性。

 

3、从矿渣中回收金属铟

从锑、锌矿渣中回收金属铟 一般采用酸化浸出-萃取法。在其他矿渣中如铁矾渣、铜渣等也含有稀散金属铟。冰铜冶炼转炉吹炼得到的铜渣中铟含量达0.6%~0.95%,具有较大的回收 价值。从铁矾渣中富集、回收铟可采用还原挥发处理和萃取提铟新工艺,将铁矾渣在高温下用炭还原,并加入某助剂使铟从渣中挥发出来,形成富铟物料,再进行浸 出-萃取-电积,可得到纯度为99.99%的高纯铟,铟回收率大于80% ,同时解决了铁矾渣的污染问题。

 

4、从烟灰中回收金属铟

冶 炼烟灰中主要含有锌、铅、铜和铁等金属,同时含有少量铟。铟在冶炼烟灰中主要以In2O3,In2S3和 In2(SO4)3等物相存在。从冶炼烟灰中回收铟主要采用酸浸—溶剂萃取法。株洲冶炼集团采用硫酸直接浸出—萃取法从铅浮渣反射炉烟尘中提取铟,在 200g?L-1硫酸溶液中浸出,铟的浸出率为90%,用P204作萃取剂,适当条件下溶液中铟的萃取率可达85%,用HCl作反萃剂,反萃率在95%以 上。在酸浸过程中加入NaCl有利于进一步提高铟的浸出率。对铅烟灰进行酸化焙烧—水浸,铟浸出率提高到88%以上。在萃取过程中采用P204水平箱萃取 法,铟的萃取率从90%提高到95%。

 

5、从废水中回收金属铟

1)萃取法

在铟的富集与回收中,萃取是重要的方法,萃取剂包括二(2一乙基己基)膦酸(HDEHP、P204),P5708、P507D、P350、PV?HQPF、Cyanex923、TR-PO、TBP和石油亚砜等。

 

2)离子交换法

萃淋树脂具有萃取剂流量少,柱负载量高,传质性能好等优点,广泛应用于分离工程。

 

3)液膜法

液膜分离法是一种高效、快速、节能的高新分离技术。以P291为流动载体,L113A为表面活性剂,液体石腊为膜增强剂,煤油为膜溶剂,硫酸和硫酸肼水溶液为内相试剂,用该乳状液膜体系对铟进行分离富集。

 

6、从合金中回收金属铟

以 铅、锡等为主体的多元合金及金属化合物,含有铟、锗等有价金属,可采用碱熔、酸浸的方法回收铟、锗等有价金属。 如电炉底铅是以铅、锡等为主体的多元合金及金属化合物,往电炉底铅中加入NaOH,进行碱熔和碱煮,将细浸出渣酸浸,两段酸浸的铟总浸出率达99%,铟直 收率达84.3%。

中国铟的提取工艺在上世纪90年代初获得突破,在有色金属工业快速发展的大背景下,铟的提取工艺普及非常快,特别是铟 价高涨之后,铟的综合回收受到 企业的普遍重视,国内科研单位和生产企业针对各种含铟物料的提铟工艺又取得长足进展,因此中国铟产量增长迅速。主要生产厂家工艺特点在于针对不同的含铟原 料采取不同的初步富集方法和溶解技术,再根据介质情况选择适合的萃取剂。如华锡集团和柳州铟泰科技有限责任公司提铟原料为含铟量大约0.2%的炼锌铁钒 渣;葫芦岛锌厂、韶关华力公司、韶关冶炼厂则是从含铟2%~3%的硬锌块中提铟;株洲冶炼厂用置换渣(铟2%~3%)作为提铟原料;柳州锌品公司从生产立 德粉的浸出渣(含铟0.2%)中提炼。[3]

 

铟 - 应用领域

铟 称得上“合金的维生素”,铟合金可用作钎焊料,铟是无铅焊料新的重要添加元素,世界无铅焊料的发展趋势有利于铟钎焊料的应用。利用铟合金熔点低的 特点还可制成特殊合金,用于消防系统的断路保护装置及自动控制系统的热控装置;添加少量铟制造的轴承合金是一般轴承合金使用寿命的4-5倍;铟合金还可用 于牙科医疗、钢铁和有色金属的防腐装饰件、塑料金属化等方面。

由于铟具有较强的抗腐蚀性及对光的反射能力,可制成军舰或客轮上的反射镜。铟对中子辐射敏感,可用作原子能工业的监控剂量材料,目前用在原子能工业的铟,大约与电子工业上的用量相近。

铟 可在蓄电池中作添加剂,在无汞碱性电池中作为缓蚀剂,可使电池成为绿色环保产品。铟在防止雾化层方面的用量不断增加,铟涂层最初是在汽车制造业中 采用,有可能普及到工业及高档民用建筑业中去。日本索尼公司发明了以铟代替钪的新阴极,这样每根电子枪的成本就降到了掺钪电子枪的十分之一左右。因此,在 电视机大功率输出、长寿命方面,铟的应用发展前景引人注目。

在光电子领域,铟及其化合物半导体具有广泛的用途。在铟基III-V族化合物 半导体如锑化铟(INSB)、磷化铟(INP)、砷化铟(INAS)等 中,研究和应用最早的是锑化铟(INSB),而最受重视并具有潜在应用前景的是磷化铟(INP),它在微波通讯向毫米波通讯方面,作为光纤通讯的激光光源 和异质结太阳能电池材料方面,都有突破性进展,展现了铟应用的可喜前景。锑化铟和砷化铟在红外探测和光磁器件方面也有重要用途。在太阳能电池中,含铟化合 物薄膜材料正异军突起,以其高转换率、低成本、便于携带等优势受到瞩目。

铜铟硒(CIS)等I-II-VI三元化合物薄膜半导体材料,由于 有价格低廉、性能良好和工艺简单的优点,将成为今后大力发展太阳电池工业的一个重 要方向,促使铟在该领域的应用不断增大。以信息技术为中心的新产业已经兴起,铟锡氧化物(ITO)是各类平板显示器不可缺少的关键材料,目前全世界的铟有 75%左右消耗在这方面,未来仍然大有作为。不仅如此,随着铟的提取、加工技术不断进步,生产成本的降低,铟的应用还在继续拓展。 [4]

 

铟 - 中国铟价面临“有市无价”

 

中国铟资源丧失定价权 日本加工后10倍价钱买回 

在经历了年初短暂的行业回暖后,目前的铟价正面临“有市无价”的尴尬。“近期铟价显现出疲弱迹象,需求也不旺,预计报价还将有小幅下滑。”天津稀有金属交易中心信息中心工作人员王先生对 《每日经济新闻》表示。

目 前铟价为现货商询价2778元~3000元/千克 (不含税),市场价格则为3100元/千克。而在今年8月份,铟价还维持在3600元/千克,短短几个 月间整整下降了500元。事实上,产量仅为银的1%的铟一直被外界看好。按照产业分析人士的估值,铟的合理价值应在2000~3000美元/千克,也就是 目前铟价的大约6倍。稀缺战略资源因何遭遇价格“尴尬”?《每日经济新闻》对此进行了调查。

19家企业联合争夺定价权

相 关资料显示,中国是全球第一大原生铟供应国,然而,这一垄断性资源优势却没有体现出 “中国价值”,铟资源价格长期遭受外国厂家的压制。19家中国具有 铟出口资质和配额的企业就MB(MetalBul-letin,英国《金属导报》周刊)的精铟报价问题发表联合声明:认为MB报道的精铟价格不能代表当前 中国市场的主流价格;2010年6月中旬以来,中国厂商未曾以MB所报道的低价出货,上述企业要求MB公正地发布即时市场价格,否则将联合业内人士拒绝参 照MB的报价,并拒绝向其提供任何有关信息。

 

19家企业“激烈”行动背后正是中国在国际铟市场缺少话语权的具体体现。据 《每日经济新闻》了解,自6月9日以来。MB对铟金属的最低报价就一直维持在 520美元/千克,中国企业对此明确提出异议,认为MB报价低于市场主流价格;MB声称其报道的低价确为中国出口的不含税价格。在几次与MB沟通未果的情 况下,中国企业通过公开申明的方式表明自己的立场。而中国有色金属工业协会铟业分会(以下简称铟业分会)也表态称,中国是铟最主要的原产地,理应在铟的价 格问题上更有话语权。“从6~7月份,铟业分会就MB低报中国铟价格与对方进行了一个半月的艰难磋商,最后迫使MB正视中国企业的要求,提高了报价。”铟 业分会会长赵立奎表示。 

 

约九成小铟厂退出市场 

铟矿多伴生在有色 金属硫化矿物中,特别是硫化锌矿,其次是方铅矿、氧化铅矿、锡矿等,需通过相关工艺才能提炼出铟,目前包括株冶集团、中金岭南、ST锌 业、ST珠峰、罗平锌电等企业都有铟业务。方正证券铟业分析师邓新荣表示,对于株冶集团等企业来说,铟并不是主营业务,而是副产品,生产成本低,因此价格 也往往不高,这也造成了铟价格一直被市场低估。

 

作为中国最重要的有色金属冶炼基地之一,云南省已探明的铟储量占到了全国的40%左右。以个旧地区为例,当地铟资源富集于铅、锡、锌、铜等矿中,原先精加工铟厂有乘风有色金属、云锡集团、自立矿冶厂等企业,另有十余家粗加工铟厂。

 

由于国内在产业链延伸方面的科技投入不够,致使铟的深加工产品不能生产,国内下游行业直接消费少,精铟必须依赖出口。但是来自欧美及铟主要消费国日本的厂家需求持续低迷,加上走私现象猖獗,出口市场只能不断以低价进行竞争。

 

与铟价的低迷相比,各种提取铟的原材料价格却在不断上涨,另外,环保等方面的要求日益严格,许多小铟厂被迫关闭。“整体关闭了90%,现在只剩下2家了.

 

个旧市双龙贵金属实业有限公司高经理在接受记者采访时表示,目前提炼铟的各种辅助材料价格一直上涨,挤压了粗铟的利润空间。由于没有成熟的处理铟生产废水的方法,这些企业承受着巨大的环保压力。“国家实行节能减排之后,光环保一项就让铟厂的成本增加了20%。”

 

压 力不止于此,2007年6月18日开始,中国对铟出口实行许可证和配额管理,并征收15%的关税。而在此前,出口铟可以享受退税13%。一进一退之间利 润的巨大下滑也让林炼焕下定决心关闭了小铟厂,转行做铜业生意了。在个旧颇有实力的乘风有色金属也停止了铟业生产,据公司段总经理介绍,由于没有利润,厂 里虽然拥有铟出口配额,但也不得不停止生产。

 

根据铟业分会的统计,从2007年开始,中国精铟产量连续3年逐年下降。为此,国家在政策上又进行了一番调整,从2009年7月1日起,对“未锻轧铟、废碎料”的出口暂定关税由原先的15%下调为5%,“铟粉末”出口暂定关税由10%下调为5%。 

 

日本控制铟加工核心技术 

虽然中小铟厂退出市场、关税提高等因素让铟出口下降,但这丝毫没有阻止外资染指中国铟资源的热情。在《每日经济新闻》的调查中发现,这些外资正以更为隐蔽的方式来获取中国的铟资源,其中以日本最为典型。 

 

日本是铟需求大国,中国70%的铟出口日本。但是日本将这些原产铟加工成高端产品后,又高价卖给中国企业。

 

中国国内铟产业的发展存在“群龙无首”、中小企业当道的现象,目前拥有100多家铟厂,铟资源呈分散状态,约95%的生产厂家年生产量仅在1~5吨,且多数只能加工初级原料产品。 

 

作 为最大的铟采购商,日本企业主要采取的是分散采购的方式。日本企业最常用的做法是到铟厂比较集中的区域挨个打听铟厂的产能,然后“狮子大开口”,要求采 购。比如你的产能只有1吨,那么他就会开口说要3吨,因为产能达不到,再加上是国际贸易,所以小铟厂往往不敢贸然接单。实际上,各家铟厂的情况基本已被日 本买家摸透,然后这些日本买家就开始动用国内招聘的中间采购商几百斤几百斤地从这些小铟厂购买,以达到压价的目的。

 

日商从大量公开采购转为小量分散采购,一方面是在采购战略性极强的物资上避开国际市场的关注,另一方面巧妙利用采购时间差,扭曲正常的供求关系,并配合以舆论宣传、恶意打压来操纵市场价格,坐收渔利。 

 

中小铟厂规模小,许多企业因资金缺乏,迫于生存的压力只能竞相压价出货,从而造成了长期以来极具战略储备意义的铟资源大量低价流失。

 

更为严重的是,在铟产业链中,中国通过消耗大量的铟资源赚取微薄的利润,而日本等国却将每年从中国大量进口的低价铟加工成高端产品,再以高价卖给中国。铟靶材(ITO粉)就是其中之一。

 

铟 是ITO靶材生产的主要原料,自1994年以来,中国国内有不少企业联合高校对相关技术进行研发,但至今无法掌握高品质ITO靶材制作所需之技术,这些 技术目前主要被日本的几大公司掌握,日本矿业公司、三井产业等4家企业控制着全世界95%左右的ITO靶材市场份额。此前有媒体报道称,株冶集团等国内公 司曾与日本企业进行过谈判,但一直无法引进相关技术。

 

以目前的市场价格为例,中国出口精铟价格仅为每吨300万元左右,但从日本进口的铟靶材(ITO粉)高达每吨两三千万元,价格接近精铟的10倍,利润可见一般。[6]

 

铟 - 投资前景

铟在世界属于稀缺资源。全球预估铟储量仅5万吨,其中可开采的占50%。由于目前未发现独立铟矿,工业通过提纯废锌、废锡的方法生产金属铟,回收率约为50-60%,这样,真正能得到的铟只有1.5-1.6万吨。

基于铟的稀缺和不可替代性,美国从1985年开始金属铟的储备。2007年,日本也将铟列入战略储备金属名单。中国拥有世界上80%的铟储量,却没有铟的定价权,走私情况猖獗,走私量甚至大于正常出口量。中国对铟资源的保护还有待加强。

上世纪二三十年代,铟首先应用于合金材料的生产。八十年代,铟被大量用于电子工业。至06年,铟的用量逾千吨,广泛用于发光材料、半导体轴承制造。铟作为一种优良的改性剂,有“金属维他命”之称。良好的商品属性支撑了铟的金融属性的开发。

铟具有很好的保值性能。当前,一些金融部门、南方的投行已经接受铟作为融资工具进行抵押贷款。

铟 还可以作为投机工具活跃于资本市场。一般金属行情波动周期为5-7年,而铟则相对的具有很好的价格波动性。每年铟价会有两轮涨势。由于日本是目前 最大的铟消费国,每年4月份日本的通关优惠政策会导致日本采购大增,铟价暴涨。而11月底前日韩企业则会为第二年生产提前2-3月大量采购,价格也会小 涨。从2001年1月至今,铟价涨跌可为跌宕起伏,最低时只有50美元/千克,最高达到1050美元/千克。如此波动的行情有利于投机者利用金融杠杆进行 有效操作,获取大量利益。

未来,铟还可能与股票债券等硬性资产相提并论,用作风险规避。铟与银价值非常相近,而相比之下铟更加稀缺。铟优 于黄金投 资的理由还在于,金价已经到达一个高位,绝无翻倍可能(全球黄金储量以16万吨计,接盘需要79万亿美元,这显然是不可能的),而铟的储量则只有1.5万 吨,用量却以每年20-30%的比率上升,未来价格有翻倍可能,甚至会回到1000美元的高位。尽管短期内市场暂时疲软,但长期来看,如果没有强力的替代 材料出现,铟的价格总会有所突破。

 

引用出處: 

 http://www.hudong.com/wiki/%E9%93%9F

歡迎來到Bewise Inc.的世界,首先恭喜您來到這接受新的資訊讓產業更有競爭力,我們是提供專業刀具製造商,應對客戶高品質的刀具需求,我們可以協助客戶滿足您對產業的不同要求,我們有能力達到非常卓越的客戶需求品質,這是現有相關技術無法比擬的,我們成功的滿足了各行各業的要求,包括:精密HSS DIN切削刀具協助客戶設計刀具流程DIN or JIS 鎢鋼切削刀具設計NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計超高硬度的切削刀具醫療配件刀具設計複合式再研磨機PCD地板專用企口鑽石組合刀具粉末造粒成型機主機版專用頂級電桿PCBN刀具PCD刀具單晶刀具PCD V-Cut捨棄式圓鋸片組粉末成型機航空機械鉸刀主機版專用頂級電汽車業刀具設計電子產業鑽石刀具木工產業鑽石刀具銑刀與切斷複合再研磨機銑刀與鑽頭複合再研磨機銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計;從微細刀具到大型刀具;從小型生產到大型量產;全自動整合;我們的技術可提供您連續生產的效能,我們整體的服務及卓越的技術,恭迎您親自體驗!!  

BW Bewise Inc. Willy Chen willy@tool-tool.com  bw@tool-tool.com  www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com/ / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting toolaerospace tool .HSS  DIN Cutting toolCarbide end millsCarbide cutting toolNAS Cutting toolNAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end milldisc milling cutter,Aerospace cutting toolhss drillФрезерыCarbide drillHigh speed steelCompound SharpenerMilling cutterINDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) Core drillTapered end millsCVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden FingerPCD V-CutterPCD Wood toolsPCD Cutting toolsPCD Circular Saw BladePVDD End Millsdiamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE Single Crystal Diamond Metric end millsMiniature end millsСпециальные режущие инструменты Пустотелое сверло Pilot reamerFraisesFresas con mango PCD (Polycrystalline diamond) ‘FresePOWDER FORMING MACHINEElectronics cutterStep drillMetal cutting sawDouble margin drillGun barrelAngle milling cutterCarbide burrsCarbide tipped cutterChamfering toolIC card engraving cutterSide cutterStaple CutterPCD diamond cutter specialized in grooving floorsV-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert PCD Diamond Tool Saw Blade with Indexable InsertNAS toolDIN or JIS toolSpecial toolMetal slitting sawsShell end millsSide and face milling cuttersSide chip clearance sawsLong end millsend mill grinderdrill grindersharpenerStub roughing end millsDovetail milling cuttersCarbide slot drillsCarbide torus cuttersAngel carbide end millsCarbide torus cuttersCarbide ball-nosed slot drillsMould cutterTool manufacturer. 

Bewise Inc.  www.tool-tool.com

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Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz. 

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт  www.tool-tool.com  для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web  www.tool-tool.com  for more info.

 

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Indium ( /ˈɪndiəm/ IN-dee-əm) is a chemical element with chemical symbol In and atomic number 49. This rare, very soft, malleable and easily fusible post-transition metal is chemically similar to aluminium. Indium was discovered in 1863 and named for the indigo blue line in its spectrum that was the first indication of its existence in zinc ores, as a new and unknown element. The metal was first isolated in the following year. Zinc ores continue to be the primary source of indium, where it is found in compound form. Very rarely the element can be found as grains of native (free) metal, but these are not of commercial importance.

Indium's current primary application is to form transparent electrodes from indium tin oxide in liquid crystal displays and touchscreens, and this use largely determines its global mining production. It is widely used in thin-films to form lubricated layers (during World War II it was widely used to coat bearings in high-performance aircraft). It is also used for making particularly low melting point alloys, and is a component in some lead-free solders.

Indium is not known to be used by any organism. In a similar way to aluminum salts, indium (III) ions can be toxic to the kidney when given by injection, but oral indium compounds do not have the chronic toxicity of salts of heavy metals, probably due to poor absorption in basic conditions. Radioactive indium-111 (in very small amounts on a chemical basis) is used in nuclear medicine tests, as a radiotracer to follow the movement of labeled proteins and white blood cells in the body.

 

 

Contents

[hide]

  • 1 Characteristics
  • 2 Isotopes
  • 3 Creation
  • 4 History
  • 5 Occurrence and consumption
    • 5.1 Resources
    • 5.2 Production
  • 6 Applications
    • 6.1 Electronics
    • 6.2 Metal and alloys
    • 6.3 Other uses
  • 7 Precautions
  • 8 See also
  • 9 References
  • 10 External links

[edit] Characteristics

 

 

 

 

Indium wetting the glass surface of a test tube

Indium is a very soft, silvery-white, relatively rare true metal with a bright luster. As a pure metal, indium emits a high-pitched "cry", when it is bent.[2] Both gallium and indium are able to wet glass. A number of standard electrode potentials, depending on the reaction under study,[3] is reported for indium:

- 0.40 In2+ + e− ↔ In+

 

 

- 0.49 In3+ + e− ↔ In2+

 

 

- 0.40 In2+ + 3 e− ↔ In+

 

 

- 0.338 In3+ + 3 e− ↔ Ino

Unlike its period 5 neighbor cadmium, indium is not a cumulative poison.

Indium demonstrates the inert pair effect to a limited extent, forming some In (I) compounds such as Indium(I) bromide. The most stable oxidation state for indium, however, is still (III). Unlike the corresponding thallium compounds, indium (I) compounds are not stable in water.

[edit] Isotopes

Main article: Isotopes of indium

Indium in nature consists of two primordial nuclides. One unusual property of indium (shared only with rhenium) is that although it possesses a stable isotope, its most common (abundant) isotope (95.7%) is slightly and measurably radioactive. This isotope, indium-115 very slowly decays by beta emission to tin. This decay has a half-life of 4.41×1014 years, four orders of magnitude larger than the age of the universe and nearly 50,000 times longer than that of natural thorium.[4]

[edit] Creation

Indium is created via the long S-process in low-medium mass stars (.6 -> 10 solar masses). This takes thousands of years to do. It requires a cadmium atom to capture sufficient neutrons and then undergo Beta decay.

[edit] History

In 1863 the German chemists Ferdinand Reich and Hieronymous Theodor Richter were testing ores from the mines around Freiberg, Saxony. They dissolved the minerals pyrite, arsenopyrite, galena and sphalerite in hydrochloric acid and distilled the raw zinc chloride. As it was known that ores from that region sometimes contain thallium they searched for the green emission lines with spectroscopic methods. The green lines were absent but a blue line was present in the spectrum. As no element was known with a bright blue emission they concluded that a new element was present in the minerals. They named the element with the blue spectral line indium, from the indigo color seen in its spectrum.[5][6] Richter went on to isolate the metal in 1864.[7] At the World Fair 1867 an ingot of 0.5 kg (1.1 lb) was presented.[8]

[edit] Occurrence and consumption

Indium ranks 61st in abundance in the Earth's crust at approximately 0.25 ppm,[9] which means it is more than three times as abundant as silver, which occurs at 0.075 ppm.[10] Fewer than 10 indium minerals are known, none occurring in significant deposits. Examples are the dzhalindite (In(OH)3) and indite (FeIn2S4).[11]

[edit] Resources

Based on content of indium in zinc ore stocks, there is a worldwide reserve base of approximately 6,000 tonnes of economically viable indium.[12] This figure has led to estimates suggesting that, at current consumption rates, there is only 13 years' supply of indium left.[13] However, the Indium Corporation, the largest processor of indium, claims that, on the basis of increasing recovery yields during extraction, recovery from a wider range of base metals (including tin, copper and other polymetallic deposits) and new mining investments, the long-term supply of indium is sustainable, reliable and sufficient to meet increasing future demands.[14]

This conclusion also seems reasonable in light of the fact that silver, three times less abundant than indium in the earths crust,[15] is currently mined at approximately 18,300 tonnes per annum,[16] which is 40 times greater than current indium mining rates.

[edit] Production

The lack of indium mineral deposits and the fact that indium is enriched in sulfidic lead, tin, copper, iron and predominately in zinc deposits, makes zinc production the main source for indium. The indium is leached from slag and dust of zinc production. Further purification is done by electrolysis.[8]

Indium is produced mainly from residues generated during zinc ore processing but is also found in iron, lead, and copper ores.[2] Canada is a leading producer of indium. The Teck Cominco refinery in Trail, British Columbia, is the largest single source indium producer, with production of 32,500 kg in 2005, 41,800 kg in 2004 and 36,100 kg in 2003. South American Silver's Malku Khota property in Bolivia is the largest resource of indium with an indicated resource of 845,000 kg and inferred resource of 968,000 kg.Adex Mining Inc.’s Mount Pleasant Mine in New Brunswick, Canada, holds about 15 to 20% of the world’s total known indium resources.[17]

The amount of indium consumed is largely a function of worldwide LCD production. Worldwide production is currently 476 tonnes per year from mining and a further 650 tonnes per year from recycling.[14] Demand has risen rapidly in recent years with the popularity of LCD computer monitors and television sets, which now account for 50% of indium consumption.[18] Increased manufacturing efficiency and recycling (especially in Japan) maintain a balance between demand and supply. Demand increased as the metal is used in LCDs and televisions, and supply decreased when a number of Chinese mining concerns stopped extracting indium from their zinc tailings. In 2002, the price was US$94 per kilogram. The recent changes in demand and supply have resulted in high and fluctuating prices of indium, which from 2005 to 2007 ranged from US$700/kg to US$1,000/kg.[12] Demand for indium may increase with large-scale manufacture of CIGS-based thin film solar technology starting by several companies in 2008, including Nanosolar and Miasole.

[edit] Applications

 

 

 

 

A magnified image of an LCD screen showing RGB pixels. Individual transistors are seen as white dots in the bottom part.

The first large-scale application for indium was as a coating for bearings in high-performance aircraft engines during World War II. Afterward, production gradually increased as new uses were found in fusible alloys, solders, and electronics. In the 1950s, tiny beads of it were used for the emitters and collectors of PNP alloy junction transistors. In the middle and late 1980s, the development of indium phosphide semiconductors and indium tin oxide thin films for liquid crystal displays (LCD) aroused much interest. By 1992, the thin-film application had become the largest end use.[19][20]

[edit] Electronics

  • Indium oxide (In2O3) and indium tin oxide (ITO) are used as a transparent conductive coating applied to glass substrates in the making of electroluminescent panels.
  • Some indium compounds such as indium antimonide, indium phosphide,[21] and indium nitride[22] are semiconductors with useful properties.
  • Indium is used in the synthesis of the semiconductor copper indium gallium selenide (CIGS), which is used for the manufacture of thin film solar cells.[23]
  • Used in light-emitting diodes (LEDs) and laser diodes based on compound semiconductors such as InGaN, InGaP that are fabricated by Metalorganic Vapor Phase Epitaxy (MOVPE) technology.
  • The ultrapure metalorganics of indium, specifically high purity trimethylindium (TMI) is used as a precursor in III-V compound semiconductors, while it is also used as the semiconductor dopant in II-VI compound semiconductors.[24]
  • As one of many substitutes for mercury in alkaline batteries to prevent the zinc from corroding and releasing hydrogen gas (e.g., US Pat US5188869)

[edit] Metal and alloys

 

 

 

 

Ductile indium wire

  • Very small amounts used in aluminium alloy sacrificial anodes (for salt water applications) to prevent passivation of the aluminium.
  • To bond gold electrical test leads to superconductors, indium is used as a conducting glue and applied under a microscope with precision tweezers.
  • In the form of a wire it is used as a vacuum seal and a thermal conductor in cryogenics and ultra-high vacuum applications. For example, in manufacturing gaskets which deform to fill gaps.[25]
  • Used as a calibration material for Differential scanning calorimetry.
  • It is an ingredient in the alloy Galinstan, which is liquid at room temperature while not being toxic like mercury.

[edit] Other uses

  • Indium tin oxide is used as a light filter in low pressure sodium vapor lamps. The infrared radiation is reflected back into the lamp, which increases the temperature within the tube and therefore improves the performance of the lamp.[20]
  • Indium's melting point of 429.7485 K (156.5985 °C) is a defining fixed point on the international temperature scale ITS-90.
  • Indium's high neutron capture cross section for thermal neutrons makes it suitable for use in control rods for nuclear reactors, typically in an alloy containing 80% silver, 15% indium, and 5% cadmium.
  • In nuclear engineering, the (n,n') reactions of 113In and 115In are used to determine magnitudes of neutron fluxes.
  • Indium is also used as a thermal interface material by personal computer enthusiasts in the form of pre-shaped foil sheets fitted between the heat-transfer surface of a microprocessor and its heat sink. The application of heat partially melts the foil and allows the indium metal to fill in any microscopic gaps and pits between the two surfaces, removing any insulating air pockets that would otherwise compromise heat transfer efficiency.
  • 111In emits gamma radiation and is used in indium leukocyte imaging, or indium scintigraphy, a technique of medical imaging. Indium leukocyte scintigraphy has many applications, including early phase drug development, and the monitoring of activity of white blood cells. For the test, blood is taken from the patient, white cells removed, labeled with the radioactive 111In, then re-injected back into the patient. Gamma imaging will then reveal any areas of on-going white cell localization such as new and developing areas of infection.

[edit] Precautions

Pure indium in metal form is considered non-toxic by most sources. In the welding and semiconductor industries, where indium exposure is relatively high, there have been no reports of any toxic side-effects.

Indium compounds, like aluminum compounds, complex with hydroxyls to form insoluble salts in basic conditions, and are thus not well-absorbed from food, giving them fairly low oral toxicty. Soluble indium (III) is toxic when delivered parenterally, however, causing damage primarily to the kidney (both inner and outer parts). Other indium compounds are toxic when administered outside the GI tract: for example, anhydrous indium trichloride (InCl3) and indium phosphide (InP) are quite toxic when delivered into the lungs (the latter is a suspected carcinogen).[

 

引用出處: 

 http://en.wikipedia.org/wiki/Indium

歡迎來到Bewise Inc.的世界,首先恭喜您來到這接受新的資訊讓產業更有競爭力,我們是提供專業刀具製造商,應對客戶高品質的刀具需求,我們可以協助客戶滿足您對產業的不同要求,我們有能力達到非常卓越的客戶需求品質,這是現有相關技術無法比擬的,我們成功的滿足了各行各業的要求,包括:精密HSS DIN切削刀具協助客戶設計刀具流程DIN or JIS 鎢鋼切削刀具設計NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計超高硬度的切削刀具醫療配件刀具設計複合式再研磨機PCD地板專用企口鑽石組合刀具粉末造粒成型機主機版專用頂級電桿PCBN刀具PCD刀具單晶刀具PCD V-Cut捨棄式圓鋸片組粉末成型機航空機械鉸刀主機版專用頂級電汽車業刀具設計電子產業鑽石刀具木工產業鑽石刀具銑刀與切斷複合再研磨機銑刀與鑽頭複合再研磨機銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計;從微細刀具到大型刀具;從小型生產到大型量產;全自動整合;我們的技術可提供您連續生產的效能,我們整體的服務及卓越的技術,恭迎您親自體驗!!  

BW Bewise Inc. Willy Chen willy@tool-tool.com  bw@tool-tool.com  www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com/ / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting toolaerospace tool .HSS  DIN Cutting toolCarbide end millsCarbide cutting toolNAS Cutting toolNAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end milldisc milling cutter,Aerospace cutting toolhss drillФрезерыCarbide drillHigh speed steelCompound SharpenerMilling cutterINDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) Core drillTapered end millsCVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden FingerPCD V-CutterPCD Wood toolsPCD Cutting toolsPCD Circular Saw BladePVDD End Millsdiamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE Single Crystal Diamond Metric end millsMiniature end millsСпециальные режущие инструменты Пустотелое сверло Pilot reamerFraisesFresas con mango PCD (Polycrystalline diamond) ‘FresePOWDER FORMING MACHINEElectronics cutterStep drillMetal cutting sawDouble margin drillGun barrelAngle milling cutterCarbide burrsCarbide tipped cutterChamfering toolIC card engraving cutterSide cutterStaple CutterPCD diamond cutter specialized in grooving floorsV-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert PCD Diamond Tool Saw Blade with Indexable InsertNAS toolDIN or JIS toolSpecial toolMetal slitting sawsShell end millsSide and face milling cuttersSide chip clearance sawsLong end millsend mill grinderdrill grindersharpenerStub roughing end millsDovetail milling cuttersCarbide slot drillsCarbide torus cuttersAngel carbide end millsCarbide torus cuttersCarbide ball-nosed slot drillsMould cutterTool manufacturer. 

Bewise Inc.  www.tool-tool.com

ようこそBewise Inc.の世界へお越し下さいませ、先ず御目出度たいのは新たな

情報を受け取って頂き、もっと各産業に競争力プラス展開。

弊社は専門なエンドミルの製造メーカーで、客先に色んな分野のニーズ

豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。

弊社は各領域に供給できる内容は:

(1)精密HSSエンドミルのR&D

(2)Carbide Cutting tools設計

(3)鎢鋼エンドミル設計

(4)航空エンドミル設計

(5)超高硬度エンドミル

(6)ダイヤモンドエンドミル

(7)医療用品エンドミル設計

(8)自動車部品&材料加工向けエンドミル設計

弊社の製品の供給調達機能は:

(1)生活産業~ハイテク工業までのエンドミル設計

(2)ミクロエンドミル~大型エンドミル供給

(3)小Lot生産~大量発注対応供給

(4)オートメーション整備調達

(5)スポット対応~流れ生産対応

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Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz. 

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镓是银白色金 属。密度5.904克/厘米3。熔点29.78℃。沸点2403℃。化合价2和3。第一电离能5.999电子伏特。凝固点很低。由于稳定固体的复杂结构, 纯液体有显著的过冷的趋势,可以放在冰浴内几天不结晶。质软、性脆,在空气中表现稳定。加热可溶于酸和碱;与沸水反应剧烈,但在室温时仅与水略有反应。高 温时能与大多数金属作用。由液态转化为固态时,膨胀率为3.1%,宜存放于塑料容器中。

纠错 编辑摘要

目录

  • 1 概述
  • 2 理化性质
  • 3 综合性质
  • 4 发现
  • 5 来源及用途
  •  

  • 1 概述
  • 2 理化性质
  • 3 综合性质
  • 4 发现
  • 5 来源及用途
  • 6 高纯镓
  • 7 硝酸镓
  • 8 磷酸镓
  • 9 氧化镓
  • 10 提炼
  • 11 参考资料

 

高纯镓

 

 

镓 - 概述

镓 是元素周期表第四周期ⅢA族元素,元素符号Ga,原子序数31,原子量69.723。1875年法国化学家布瓦博德朗在闪锌矿中离析出几克性质与门捷列夫 预言的“类铝”相同的元素,并命名。元素名来源于他的祖国,愿意为“法国的”。镓是化学史上第一个先从理论预言,后在自然界中被发现验证的化学元素。镓在 地壳中的含量约0.001%,含量最富的锗石中也只含0.5%左右。固体镓为蓝灰色,液体镓为银白色;熔点29.78°C,沸点2403°C,固体密度 5.907克/厘米³。镓与钒、铌、锆形成的合金具有超导性。

 

镓 - 理化性质

 

金 属镓固态为淡蓝色,液态呈银白色,熔点29.93`C,沸点2403`C,密度5.9g电阻率27x10-8fI•m,液态镓的蒸气压很 低,1350℃时仅为133.3Pa,在所有元素中,镓的液态温度范围最宽(从29.93-2403'C),由于固态镓的结构复杂,液态镓易出现过冷现 象,在快速冷却时,液体镓可以在一40℃的过冷状态下仍保持液态。液态镓转为固态时,镓体积膨胀,膨胀率达3.2%,液态镓几乎能润湿所有物质的表面,具 有优良的浇注性能,镓能迅速扩散到某些金属的晶格内,在高温下能和许多金属生成合金。

镓的外电子层构型为「Ar]3d104s2p1, 有+1--+3三种价态,其中以+3价化合物最稳定。镓在常温空气中稳定,260℃时才开始和氧作 用,100℃时钵不和水作用,但200℃时高压水蒸气会氧化镓生成氢氧化镓。镓的化学性质和锌、铝相似,属于两性元素。和铝相似,既能溶于酸,又能溶于 碱。镓的化学活性和锌相近,但不如铝活泼。镓缓慢溶于硫酸和盐酸中,室温下不溶于硝酸,但溶于热的硝酸、高氯酸、氢氟酸和王水中。随纯度提高,镓在酸和碱 中溶解速度变慢,镓能和卤素作用生成各种卤化物,和硫、硒、磷、砷、锑生成半导体性质的化合物,金属镓腐蚀很强,镓对人体无害,是一种安全金属。

 

镓 - 综合性质

 

元素名称:镓

元素原子量:69.72

元素类型:金属

原子体积:(立方厘米/摩尔):11.8

高纯三甲基镓

 

地壳中含量:(ppm):18

元素在太阳中的含量:(ppm):0.04

元素在海水中的含量:(ppm):  0.00001

 

发现人:布瓦博德朗    发现年代:1875年

原子序数:31

元素符号:Ga

元素英文名称:Gallium

相对原子质量:69.72

核内质子数:31

核外电子数:31

核电核数:31

质子质量:5.1863E-26

质子相对质量:31.217

所属周期:4

所属族数:IIIA

摩尔质量:70

氢化物:GaH3

氧化物:Ga2O3

最高价氧化物化学式:Ga2O3

密度:5.907

熔点:29.78

沸点:2403.0

以下为增加内容:

氧化态:Main  Ga+3

Other  Ga+1, Ga+2

声音在其中的传播速率:(m/S):2740

 

晶胞参数:

a = 451.97 pm

b = 766.33 pm

c = 452.6 pm

α = 90°

β = 90°

γ = 90°

 

电离能 (kJ/ mol) 

M - M+ 578.8

M+ - M2+ 1979

M2+ - M3+ 2963

M3+ - M4+ 6200

M4+ - M5+ 8700

M5+ - M6+ 11400

M6+ - M7+ 14400

M7+ - M8+ 17700

M8+ - M9+ 22300

M9+ - M10+ 26100

 

外围电子排布:4s2 4p1

晶体结构:晶胞为正交晶胞。

莫氏硬度:1.5 

核外电子排布:2,8,18,3

颜色和状态:蓝白色金属

原子半径:1.81

常见化合价:+3

 

镓 - 发现

在化学元素周期系建立的过程中,性质相似的元素成为一族已为化学家们接受。当时法国化学家布瓦邦德朗利用光谱分析发觉到,在铝族中,在铝和铟之间缺少一个元

金属镓,镓锭

素。 从1865年开始,他用分光镜寻找这个元素, 分析了许多矿物,但是都没有成功。直到1875年9月,布瓦邦德朗在法国化学家们面前表演了一组实验,证明新元素的存在。当时布瓦邦德朗测定的新元素比重 是4.7,而门捷列夫根据元素周期系推算出的比重应该是5.9~6。布瓦邦德朗又重新测定了这种新元素,证实了比重应该是5.96。他将此物质命名为 gallium,元素符号定为Ga。

镓的发现不仅是一个化学元素的发现,它的发现引起了科学家们对门捷列夫制定的元素周期系的重视,使化学元素周期系得到赞扬和承认。发现人:布瓦博德朗,发现时间和地点:1875在法国的布瓦博德朗在用光谱分析从闪锌矿得到的提取物时,发现了镓。。

 

镓 - 来源及用途

 

元素来源:它凝固时膨胀,,常是作为从铝土矿中提取铝或从锌矿石中提取锌时的副产物得到的。

元 素用途:用于半导体工业,发光二极管和 砷化镓激光二极管。其他化合物:GaCl3-氯化锌,一种稀有蓝白色三价金属元素,在低温时硬而脆,而一超过室温就熔融。镓的化学活性低于铝,在常温下几 乎不受氧和水的侵蚀,只在高温下才被氧化;它与稀酸作用缓慢,可溶于热的强酸及强碱中,分别形成镓盐或镓酸盐;卤素与镓反应生成三卤化镓或一卤化镓;镓在 高温下能与硫、硒、碲、磷、砷、锑反应,生成的化合物都有半导体性质;镓的氧化和氢氧化物都是两性的,可溶于酸和碱中。镓可用作高温温度计和真空装置中的 密封液;镓的最重要的应用是在制造半导体器件方面;镓还用来制造阴极蒸汽灯等。

 

镓 - 高纯镓

高纯镓:high purity gallium,一般杂质总含量在10

高纯镓

-5 以下的金属镓。按镓含量分为5N,6N,7N和8N共四种级别。质软,淡蓝色光泽。熔点29.78℃。沸点2403℃。斜方晶型,各向异性显著。0℃的电 阻率沿a,b,c三个轴分别为1.75×10-6Ω•m,8.20×10-6Ω•m和55.30×10-6Ω•m。超纯镓剩余电阻率比值 ρ300K/ρ4.2K为55 000。采用化学处理、电解精炼、真空蒸馏、区域熔炼、拉单晶等多种工艺方法制备。主要用于电子工业和通讯领域,是制取各种镓化合物半导体的原料,硅、锗 半导体的掺杂剂,核反应堆的热交换介质。

 

镓 - 硝酸镓

分子 式:Ga(NO3)3•9H2O,用途:为制取镓化合物原料。性质:无色透明结晶体,易吸潮,空气中易分解。易溶于水,20℃时每100g水可溶解 295g,可溶于乙醇,但不溶于乙醚。102℃开始脱水,170℃完全分解,生成二氧化镓。由浓硝酸和氢氧化镓或金属镓作用制取。

 

镓 - 磷酸镓

 

磷酸镓:gallium phosphate

分子式:GaPO4•2H2O 

性质:白色无定形粉末,难溶于水(溶度积1.0×10-21)。140℃脱水。540℃转化为晶体。密度3.26g/cm3。熔点1670℃。和磷酸作用生成磷酸氢镓化合物。

制法:由镓盐溶液和碱金属磷酸盐在pH=5时反应制取。

 

镓 - 氧化镓

氧化镓别名三氧化二镓,氧化镓(Ga2O3)是一种宽禁带半导体,Eg=4

高纯试剂 氧化镓

.9eV,其导电性能和发光特性长期以来一直引起人们的注意。-Ga2O3是一种透明的氧化物半导体材料,在光电子器件方面有广阔的应用前景 ,被用作于Ga基半导体材料的绝缘层,以及紫外线滤光片。它还可以用作O2化学探测器。

 

 

镓 - 提炼

镓 在常温下,看上去象一块锡,如果你想把它放在手心里,它马上就熔化了,成为银亮的小珠。原来镓的熔点很低,只有29.8℃。镓的熔点虽然很低,可是沸点却 非常高,竟高达2070℃!人们就利用镓的这个特性来制造测量高温的温度计。把这种温度计伸进炉火熊熊的炼钢炉中,玻璃外壳都快熔化了,里边的镓还没有沸 腾,如果用耐高温的石英玻璃来制造镓温度计的外壳,它能够一直测到1500℃的高温。所以,人们常用这种温度计来测量反应炉、原子反应堆的温度。

 

镓具有较好的铸造特性,由于它“热缩冷胀”,被用来制造

金属镓

铅 字合金,使字体清晰。在原子能工业中,用镓作为热传导介质,把反应堆中的热量传导出来。 镓与许多金属,如铋、铅、锡、镉,铟、铊等,生成熔点低于60℃的易熔合金。其中如含铟25%的镓铟合金(熔点16℃),含锡8%的镓锡合金(熔点 20℃),可以用在电路熔断器和各种保险装置上,温度一高,它们就会自动熔化断开,起到安全保险的作用。

 

镓同玻璃合作,有增强玻璃折射率的效能,可以用来制造特种光学玻璃。因为镓对光的反射能力特别强,同时又能很好地附着在玻璃上,承受较高的温度,所以用它做反光镜最适宜,镓镜能把70%以上射来的光反射出去。

镓 的一些化合物,如今与尖端科学技术结下了不解之缘。砷化镓是近年来新发现的一种半导体材料,性能优良,用它作为电子元件,可以使电子设备的体积大为缩小, 实现微型化。人们还用砷化镓做元件制成了激光器,这是一种效率高、体积小的新型激光器。镓和磷的化合物——磷化镓是一种半导体发光元件,能够射出红光或绿 光,人们把它做成了各种阿拉伯数字形状,在电子计算机中,就利用它来显示计算结果。

 

引用出處: 

 http://www.hudong.com/wiki/%E9%95%93

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Gallium ( /ˈɡæliəm/ GAL-ee-əm) is a chemical element that has the symbol Ga and atomic number 31. Elemental gallium does not occur in nature, but as the gallium(III) salt in trace amounts in bauxite and zinc ores. A soft silvery metallic poor metal, elemental gallium is a brittle solid at low temperatures. As it liquefies slightly above room temperature, it will melt in the hand. Its melting point is used as a temperature reference point, and from its discovery in 1875 to the semiconductor era, its primary uses were in high-temperature thermometric applications and in preparation of metal alloys with unusual properties of stability, or ease of melting; some being liquid at room temperature or below. The alloy Galinstan (68.5% Ga, 21.5% In, 10% Sn) has a melting point of about −19 °C (−2 °F).

In semiconductors, the major-use compound is gallium arsenide used in microwave circuitry and infrared applications. Gallium nitride and indium gallium nitride, minority semiconductor uses, produce blue and violet light-emitting diodes (LEDs) and diode lasers. Semiconductor use is now almost the entire (> 95%) world market for gallium, but new uses in alloys and fuel cells continue to be discovered.

Gallium is not known to be essential in biology, but because of the biological handling of gallium's primary ionic salt gallium(III) as though it were iron(III), the gallium ion localizes to and interacts with many processes in the body in which iron(III) is manipulated. As these processes include inflammation, which is a marker for many disease states, several gallium salts are used, or are in development, as both pharmaceuticals and radiopharmaceuticals in medicine.

 

 

Contents

[hide]

  • 1 Notable characteristics
  • 2 History
  • 3 Occurrence
  • 4 Production
  • 5 Applications
    • 5.1 Semiconductors
    • 5.2 Wetting and alloy improvement
    • 5.3 Galinstan and other liquid alloys
    • 5.4 Energy storage
    • 5.5 Biomedical applications
      • 5.5.1 As gallium(III) salts
      • 5.5.2 As radiogallium salts
    • 5.6 Other uses
  • 6 Chemistry
    • 6.1 Chalcogen compounds
    • 6.2 Aqueous chemistry
    • 6.3 Pnictogen compounds
    • 6.4 Halides
    • 6.5 Hydrogen compounds
  • 7 Precautions
  • 8 See also
  • 9 References
  • 10 External links

[edit] Notable characteristics

Elemental gallium is not found in nature, but it is easily obtained by smelting. Very pure gallium metal has a brilliant silvery color and its solid metal fractures conchoidally like glass. Gallium metal expands by 3.1 percent when it solidifies, and therefore storage in either glass or metal containers is avoided, due to the possibility of container rupture with freezing. Gallium shares the higher-density liquid state with only a few materials like silicon, germanium, bismuth, antimony and water.

Gallium attacks most other metals by diffusing into their metal lattice. Gallium for example diffuses into the grain boundaries of Al/Zn alloys[1] or steel,[2] making them very brittle. Also, gallium metal easily alloys with many metals, and was used in small quantities as a plutonium-gallium alloy in the plutonium cores of the first and third nuclear bombs, to help stabilize the plutonium crystal structure.[3]

The melting point of 302.9146 K (29.7646°C, 85.5763°F) is near room temperature. Gallium's melting point (mp) is one of the formal temperature reference points in the International Temperature Scale of 1990 (ITS-90) established by BIPM.[4][5][6] The triple point of gallium of 302.9166 K (29.7666°C, 85.5799°F), is being used by NIST in preference to gallium's melting point.[7]

Gallium is a metal that will melt in one's hand. This metal has a strong tendency to supercool below its melting point/freezing point. Seeding with a crystal helps to initiate freezing. Gallium is one of the metals (with caesium, rubidium, francium and mercury) which are liquid at or near normal room temperature, and can therefore be used in metal-in-glass high-temperature thermometers. It is also notable for having one of the largest liquid ranges for a metal, and (unlike mercury) for having a low vapor pressure at high temperatures. Unlike mercury, liquid gallium metal wets glass and skin, making it mechanically more difficult to handle (even though it is substantially less toxic and requires far fewer precautions). For this reason as well as the metal contamination problem and freezing-expansion problems noted above, samples of gallium metal are usually supplied in polyethylene packets within other containers.

 

 

 

 

Crystallization of gallium from the melt

Gallium does not crystallize in any of the simple crystal structures. The stable phase under normal conditions is orthorhombic with 8 atoms in the conventional unit cell. Each atom has only one nearest neighbor (at a distance of 244 pm) and six other neighbors within additional 39 pm. Many stable and metastable phases are found as function of temperature and pressure.

The bonding between the nearest neighbors is found to be of covalent character, hence Ga2 dimers are seen as the fundamental building blocks of the crystal. This explains the drop of the melting point compared to its neighbour elements aluminium and indium. The compound with arsenic, gallium arsenide is a semiconductor commonly used in light-emitting diodes.

High-purity gallium is dissolved slowly by mineral acids.

Gallium has no known biological role, although it has been observed to stimulate metabolism.[8]

[edit] History

Gallium (the Latin Gallia means "Gaul", essentially modern France) was discovered spectroscopically by Paul Emile Lecoq de Boisbaudran in 1875 by its characteristic spectrum (two violet lines) in an examination of a zinc blende from the Pyrenees.[9] Before its discovery, most of its properties had been predicted and described by Dmitri Mendeleev (who had called the hypothetical element "eka-aluminium" on the basis of its position in his periodic table). Later, in 1875, Lecoq obtained the free metal by electrolysis of its hydroxide in potassium hydroxide solution. He named the element "gallia" after his native land of France. It was later claimed that, in one of those multilingual puns so beloved of men of science in the early 19th century, he had also named gallium after himself, as his name, "Le coq", is the French for "the rooster", and the Latin for "rooster" is "gallus"; however, in an 1877 article Lecoq denied this supposition.[10] (The supposition was also noted in Building Blocks of the Universe, a book on the elements by Isaac Asimov; cf. the naming of the J/ψ meson.)

[edit] Occurrence

Gallium does not exist in free form in nature, and the few high-gallium minerals such as gallite (CuGaS2) are too rare to serve as a primary source of the element or its compounds. Its abundance in the Earth's crust is approximately 16.9 ppm.[11] Gallium is found and extracted as a trace component in bauxite and to a small extent from sphalerite. The amount extracted from coal, diaspore and germanite in which gallium is also present is negligible. The United States Geological Survey (USGS) estimates gallium reserves to exceed 1 million tonnes, based on 50 ppm by weight concentration in known reserves of bauxite and zinc ores.[12][13] Some flue dusts from burning coal have been shown to contain small quantities of gallium, typically less than 1% by weight.[14][15][16][17]

[edit] Production

The only two economic sources for gallium are as byproduct of aluminium and zinc production, while the sphalerite for zinc production is the minor source. Most gallium is extracted from the crude aluminium hydroxide solution of the Bayer process for producing alumina and aluminium. A mercury cell electrolysis and hydrolysis of the amalgam with sodium hydroxide leads to sodium gallate. Electrolysis then gives gallium metal. For semiconductor use, further purification is carried out using zone melting, or else single crystal extraction from a melt (Czochralski process). Purities of 99.9999% are routinely achieved and commercially widely available.[18] An exact number for the world wide production is not available, but it is estimated that in 2007 the production of gallium was 184 tonnes with less than 100 tonnes from mining and the rest from scrap recycling.[12]

[edit] Applications

[edit] Semiconductors

 

 

 

 

Gallium based blue LEDs

 

 

 

 

Gallium phosphate crystal

The semiconductor applications are the main reason for the low-cost commercial availability of the extremely high-purity (99.9999+%) metal.

Gallium arsenide (GaAs) and gallium nitride (GaN) used in electronic components represented about 98% of the gallium consumption in the United States in 2007. About 66% of semiconductor gallium is used in the U.S. in integrated circuits (mostly gallium arsenide), such as the manufacture of ultra-high speed logic chips and MESFETs for low-noise microwave preamplifiers in cell phones. About 20% is used in optoelectronics.[12] World wide gallium arsenide makes up 95% of the annual global gallium consumption.[18]

Gallium arsenide is used in optoelectronics in a variety of infrared applications. Aluminium gallium arsenide (AlGaAs) is used in high-powered infrared laser diodes. As a component of the semiconductors indium gallium nitride and gallium nitride, gallium is used to produce blue and violet optoelectronic devices, mostly laser diodes and light-emitting diodes. For example, gallium nitride 405 nm diode lasers are used as a violet light source for higher-density compact disc data storage, in the Blu-ray Disc standard.[19]

Gallium is used as a dopant for the production of solid-state devices such as transistors. However, worldwide the actual quantity used for this purpose is minute, since dopant levels are usually of the order of a few parts per million.

Multijunction photovoltaic cells, developed for satellite power applications, are made by molecular beam epitaxy or metalorganic vapour phase epitaxy of thin films of gallium arsenide, indium gallium phosphide or indium gallium arsenide.The Mars Exploration Rovers and several satellites use triple junction gallium arsenide on germanium cells.[20] Gallium is the rarest component of new photovoltaic compounds (such as copper indium gallium selenium sulfide or Cu(In,Ga)(Se,S)2) for use in solar panels as a more efficient alternative to crystalline silicon.[21]

[edit] Wetting and alloy improvement

  • Because gallium wets glass or porcelain, gallium can be used to create brilliant mirrors. When the wetting action of gallium-alloys is not desired (as in Galinstan glass thermometers), the glass must be protected with a transparent layer of gallium(III) oxide.[22]
  • Gallium readily alloys with most metals, and has been used as a component in low-melting alloys. The plutonium used in nuclear weapon pits is machined by alloying with gallium to stabilize its δ phase.[23]
  • Gallium added in quantities up to 2% in common solders can aid wetting and flow characteristics.

[edit] Galinstan and other liquid alloys

A nearly eutectic alloy of gallium, indium, and tin is a room temperature liquid which is widely available in medical thermometers, replacing problematic mercury. This alloy, with the trade-name Galinstan (with the "-stan" referring to the tin), has a low freezing point of −19 °C (−2.2°F).[24] It has been suggested that this family of alloys could also be used to cool computer chips in place of water.[25] Much research is being devoted to gallium alloys as substitutes for mercury dental amalgams, but these compounds have yet to see wide acceptance.

[edit] Energy storage

Aluminium is reactive enough to reduce water to hydrogen, being oxidized to aluminium oxide. However, the aluminium oxide forms a protective coat which prevents further reaction. Galinstan has been applied to activate aluminium (removing the oxide coat), so that aluminium can react with water, generating hydrogen and steam in a reaction being considered as a helpful step in a hydrogen economy.[26][dubious – discuss] A number of other gallium-aluminium alloys are also usable for the purpose of essentially acting as chemical energy store to generate hydrogen from water, on-site.

After reaction with water the resultant aluminium oxide and gallium mixture must be reformed back into electrodes with energy input.[26][27] The thermodynamic efficiency of the aluminium smelting process is estimated as 50%.[28] Therefore, at most only half the energy that goes into smelting the aluminium could be recovered by a hydrogen fuel cell.

[edit] Biomedical applications

[edit] As gallium(III) salts

  • Gallium nitrate (brand name Ganite) has been used as an intravenous pharmaceutical to treat hypercalcemia associated with tumor metastasis to bones. Gallium is thought to interfere with osteoclast function. It may be effective when other treatments for maligancy-associated hypercalcemia are not.[29]
  • Gallium maltolate, an orally-aborbable form of gallium(III) ion, is in clinical and preclinical trials as a potential treatment for a number of types of cancer, infectious disease, and inflammatory disease.[30]
  • Research is being conducted to determine whether gallium ion can be used to fight bacterial infections in people with cystic fibrosis. Gallium is similar in size to iron, an essential nutrient for respiration. When gallium ions are mistakenly picked up by bacteria such as Pseudomonas, the bacteria's ability to respire is interfered with and the bacteria die. The mechanism behind this is that iron is redox active, which allows for the transfer of electrons during respiration, but gallium is redox inactive.[31][32]

[edit] As radiogallium salts

Gallium-67 salts such as gallium citrate and gallium nitrate are used as radiopharmaceutical agents in a nuclear medicine imaging procedure commonly referred to as a gallium scan. The form or salt of gallium is not important, since it is the free dissolved gallium ion Ga3+ which is the active radiotracer. For these applications, the radioactive isotope 67Ga is used. The body handles Ga3+ in many ways as though it were iron, and thus it is bound (and concentrates) in areas of inflammation, such as infection, and also areas of rapid cell division. This allows such sites to be imaged by nuclear scan techniques. This use has largely been replaced by fluorodeoxyglucose (FDG) for positron emission tomography, "PET" scan and indium-111 labelled leukocyte scans. However, the localization of gallium in the body has some properties which make it unique in some circumstances from competing modalities using other radioisotopes.

Gallium-68, a positron emitter with a half life of 68 min., is now used as a diagnostic radionuclide in CT-PET when linked to pharmaceutical preparations such as DOTATOC, a somatostatin analogue used for neuroendocrine tumors investigation, and DOTATATE, a newer one, used for neuroendocrine metastasis and lung neuroendocrine cancer, such as certain types of microcytoma. Galium-68's preparation as a pharmaceutical is chemical and the radionuclide is extracted by elution from germanium-68, a synthetic radioisotope of germanium, in gallium-68 generators.

[edit] Other uses

  • Magnesium gallate containing impurities (such as Mn2+), is beginning to be used in ultraviolet-activated phosphor powder.
  • Neutrino detection. Possibly the largest amount of pure gallium ever collected in a single spot is the Gallium-Germanium Neutrino Telescope used by the SAGE experiment at the Baksan Neutrino Observatory in Russia. This detector contains 55-57 tonnes of liquid gallium.[33] Another experiment was the GALLEX neutrino detector operated in the early 1990s in an Italian mountain tunnel. The detector contained 12.2 tons of watered gallium-71. Solar neutrinos caused a few atoms of Ga-71 to become radioactive Ge-71, which were detected. The solar neutrino flux deduced was found to have a deficit of 40% from theory. This was not explained until better solar neutrino detectors and theories were constructed (see SNO).[34]
  • As a liquid metal ion source for a focused ion beam.
  • As alloying element in the magnetic shape memory alloy Ni-Mn-Ga.
  • In a classic prank by scientists, who fashion gallium spoons and serve tea to unsuspecting guests. The spoons melt in the hot tea.[35]

[edit] Chemistry

Gallium is found primarily in the +3 oxidation state. The +1 oxidation is also attested in some compounds, although they tend to disproportionate into elemental gallium and gallium(III) compounds. What are sometimes referred to as gallium(II) compounds are actually mixed-oxidation state compounds containing both gallium(I) and gallium(III).[36]

[edit] Chalcogen compounds

At room temperature, gallium metal is unreactive towards air and water due to the formation of a passive, protective oxide layer. At higher temperatures, however, it reacts with oxygen in the air to form gallium(III) oxide, Ga2O3.[36] Reducing Ga2O3 with elemental gallium in vacuum at 500 °C to 700 °C yields the dark brown gallium(I) oxide, Ga2O.[37]:285 Ga2O is a very strong reducing agent, capable of reducing H2SO4 to H2S.[37]:207 It disproportionates at 800 °C back to gallium and Ga2O3.[38]

Gallium(III) sulfide, Ga2S3, has 3 possible crystal modifications.[38]:104 It can be made by the reaction of gallium with hydrogen sulfide (H2S) at 950 °C.[37]:162 Alternatively, Ga(OH)3 can also be used at 747 °C:[39]

 

2 Ga(OH)3 + 3 H2S → Ga2S3 + 6 H2O

Reacting a mixture of alkali metal carbonates and Ga2O3 with H2S leads to the formation of thiogallates containing the [Ga2S4]2− anion. Strong acids decompose these salts, releasing H2S in the process.[38]:104-105 The mercury salt, HgGa2S4, can be used as a phosphor.[40]

Gallium also forms sulfides in lower oxidation states, such as gallium(II) sulfide and the green gallium(I) sulfide, the latter of which is produced from the former by heating to 1000 °C under a stream of nitrogen.[38]:94

The other binary chalcogenides, Ga2Se3 and Ga2Te3, have zincblende structure. They are all semiconductors, but are easily hydrolysed, limiting their usefulness.[38]:104

[edit] Aqueous chemistry

Strong acids dissolve gallium, forming gallium(III) salts such as Ga2(SO4)3 and Ga(NO3)3. Aqueous solutions of gallium(III) salts contain the hydrated gallium ion, [Ga(H2O)6]3+.[41]:1033 Gallium(III) hydroxide, Ga(OH)3, may be precipitated from gallium(III) solutions by adding ammonia. Dehydrating Ga(OH)3 at 100 °C produces gallium oxide hydroxide, GaO(OH).[37]:140-141

 

Alkaline hydroxide solutions dissolve gallium, forming gallate salts containing the Ga(OH)−

4 anion.[36][41]:1033[42] Gallium hydroxide, which is amphoteric, also dissolves in alkali to form gallate salts.[37]:141 Although earlier work suggested Ga(OH)3−

6 as another possible gallate anion,[43] this species was not found in later work.[42]

[edit] Pnictogen compounds

Gallium reacts with ammonia at 1050 °C to form gallium nitride, GaN. Gallium also forms binary compounds with phosphorus, arsenic, and antimony: gallium phosphide (GaP), gallium arsenide (GaAs), and gallium antimonide (GaSb). These compounds have the same structure as ZnS, and have important semiconducting properties.[41]:1034 GaP, GaAs, and GaSb can be synthesized by the direct reaction of gallium with elemental phosphorus, arsenic, or antimony.[38]:99 They exhibit higher electrical conductivity than GaN.[38]:101 GaP can also be synthesized by the reaction of Ga2O with phosphorus at low temperatures.[44]

Gallium also forms ternary nitrides; for example:[38]:99

 

Li3Ga + N2 → Li3GaN2

Similar compounds with phosphorus and antimony also exist: Li3GaP2 and Li3GaAs2. These compounds are easily hydrolyzed by dilute acids and water.[38]:101

[edit] Halides

Gallium(III) oxide reacts with fluorinating agents such as HF or F2 to form gallium(III) fluoride, GaF3. It is an ionic compound strongly insoluble in water. However, it does dissolve in hydrofluoric acid, in which it forms an adduct with water, GaF3·3H2O. Attempting to dehydrate this adduct instead forms GaF2OH·nH2O. The adduct reacts with ammonia to form GaF3·3NH3, which can then be heated to form anhydrous GaF3.[37]:128-129

Gallium(III) chloride is formed by the reaction of gallium metal with chlorine gas.[36] Unlike the trifluoride, gallium(III) chloride exists as dimeric molecules, Ga2Cl6, with a melting point of 78 °C. This is also the case for the bromide and iodide, Ga2Br6 and Ga2I6.[37]:133

 

Like the other group 13 trihalides, gallium(III) halides are Lewis acids, reacting as halide acceptors with alkali metal halides to form salts containing GaX−

4 anions, where X is a halogen. They also react with alkyl halides to form carbocations and GaX−

4.[37]:136-137

When heated to a high temperature, gallium(III) halides react with elemental gallium to form the respective gallium(I) halides. For example, GaCl3 reacts with Ga to form GaCl:

 

2 Ga + GaCl3 3 GaCl (g)

At lower temperatures, the equilibrium shifts toward the left and GaCl disproportionates back to elemental gallium and GaCl3. GaCl can also be made by the reaction of Ga with HCl at 950 °C; it can then be condensed as red solid.[41]:1036

Gallium(I) compounds can be stabilized by forming adducts with Lewis acids. For example:

 

GaCl + AlCl3 → Ga+[AlCl4]−

The so-called "gallium(II) halides", GaX2, are actually adducts of gallium(I) halides with the respective gallium(III) halides, having the structure Ga+[GaX4]−. For example:[36][41]:1036[45]

 

GaCl + GaCl3 → Ga+[GaCl4]−

[edit] Hydrogen compounds

Like aluminium, gallium also forms a hydride, GaH3, known as gallane, which may be obtained by the reaction of lithium gallanate (LiGaH4) with gallium(III) chloride at −30 °C:[41]:1031

 

3 LiGaH4 + GaCl3 → 3 LiCl + 4 GaH3

In the presence of dimethyl ether as solvent, GaH3 polymerizes to (GaH3)n. If no solvent is used, the dimer Ga2H6 (digallane) is formed as a gas. Its structure is similar to diborane, having two hydrogen atoms bridging the two gallium centers,[41]:1031 unlike α-AlH3 in which aluminium has a coordination number of 6.[41]:1008

Gallane is unstable above −10 °C, decomposing to elemental gallium and hydrogen.[46]

[edit] Precautions

While not considered toxic, the data about gallium are inconclusive. Some sources suggest that it may cause dermatitis from prolonged exposure; other tests have not caused a positive reaction. Like most metals, finely divided gallium loses its luster and powdered gallium appears gray. Thus, when gallium is handled with bare hands, the extremely fine dispersion of liquid gallium droplets, which results from wetting skin with the metal, may appear as a gray skin stain.

 

引用出處: 

 http://en.wikipedia.org/wiki/Gallium

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(6)ダイヤモンドエンドミル

(7)医療用品エンドミル設計

(8)自動車部品&材料加工向けエンドミル設計

弊社の製品の供給調達機能は:

(1)生活産業~ハイテク工業までのエンドミル設計

(2)ミクロエンドミル~大型エンドミル供給

(3)小Lot生産~大量発注対応供給

(4)オートメーション整備調達

(5)スポット対応~流れ生産対応

弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。     

Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz.

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт  www.tool-tool.com  для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web  www.tool-tool.com  for more info.

歡迎來到Bewise Inc.的世界,首先恭喜您來到這接受新的資訊讓產業更有競爭力,我們是提供專業刀具製造商,應對客戶高品質的刀具需求,我們可以協助客戶滿足您對產業的不同要求,我們有能力達到非常卓越的客戶需求品質,這是現有相關技術無法比擬的,我們成功的滿足了各行各業的要求,包括:精密HSS DIN切削刀具協助客戶設計刀具流程DIN or JIS 鎢鋼切削刀具設計NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計超高硬度的切削刀具醫療配件刀具設計複合式再研磨機PCD地板專用企口鑽石組合刀具粉末造粒成型機主機版專用頂級電桿PCBN刀具PCD刀具單晶刀具PCD V-Cut捨棄式圓鋸片組粉末成型機航空機械鉸刀主機版專用頂級電汽車業刀具設計電子產業鑽石刀具木工產業鑽石刀具銑刀與切斷複合再研磨機銑刀與鑽頭複合再研磨機銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計;從微細刀具到大型刀具;從小型生產到大型量產;全自動整合;我們的技術可提供您連續生產的效能,我們整體的服務及卓越的技術,恭迎您親自體驗!!

BW Bewise Inc. Willy Chen willy@tool-tool.com  bw@tool-tool.com  www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com/ / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting toolaerospace tool .HSS  DIN Cutting toolCarbide end millsCarbide cutting toolNAS Cutting toolNAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end milldisc milling cutter,Aerospace cutting toolhss drillФрезерыCarbide drillHigh speed steelCompound SharpenerMilling cutterINDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) Core drillTapered end millsCVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden FingerPCD V-CutterPCD Wood toolsPCD Cutting toolsPCD Circular Saw BladePVDD End Millsdiamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE Single Crystal Diamond Metric end millsMiniature end millsСпециальные режущие инструменты Пустотелое сверло Pilot reamerFraisesFresas con mango PCD (Polycrystalline diamond) ‘FresePOWDER FORMING MACHINEElectronics cutterStep drillMetal cutting sawDouble margin drillGun barrelAngle milling cutterCarbide burrsCarbide tipped cutterChamfering toolIC card engraving cutterSide cutterStaple CutterPCD diamond cutter specialized in grooving floorsV-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert PCD Diamond Tool Saw Blade with Indexable InsertNAS toolDIN or JIS toolSpecial toolMetal slitting sawsShell end millsSide and face milling cuttersSide chip clearance sawsLong end millsend mill grinderdrill grindersharpenerStub roughing end millsDovetail milling cuttersCarbide slot drillsCarbide torus cuttersAngel carbide end millsCarbide torus cuttersCarbide ball-nosed slot drillsMould cutterTool manufacturer.

Bewise Inc.  www.tool-tool.com

ようこそBewise Inc.の世界へお越し下さいませ、先ず御目出度たいのは新たな

情報を受け取って頂き、もっと各産業に競争力プラス展開。

弊社は専門なエンドミルの製造メーカーで、客先に色んな分野のニーズ

豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。

弊社は各領域に供給できる内容は:

(1)精密HSSエンドミルのR&D

(2)Carbide Cutting tools設計

(3)鎢鋼エンドミル設計

(4)航空エンドミル設計

(5)超高硬度エンドミル

(6)ダイヤモンドエンドミル

(7)医療用品エンドミル設計

(8)自動車部品&材料加工向けエンドミル設計

弊社の製品の供給調達機能は:

(1)生活産業~ハイテク工業までのエンドミル設計

(2)ミクロエンドミル~大型エンドミル供給

(3)小Lot生産~大量発注対応供給

(4)オートメーション整備調達

(5)スポット対応~流れ生産対応

弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。   

Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz.

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт  www.tool-tool.com  для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web  www.tool-tool.com  for more info.

 

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