[edit] Pigments, Additives and Coatings
About 95% of titanium ore extracted from the Earth is destined for refinement into titanium dioxide (TiO2), an intensely white permanent pigment used in paints, paper, toothpaste, and plastics.[32] It is also used in cement, in gemstones, as an optical opacifier in paper,[33] and a strengthening agent in graphite composite fishing rods and golf clubs.
TiO2 powder is chemically inert, resists fading in sunlight, and is very opaque: this allows it to impart a pure and brilliant white color to the brown or gray chemicals that form the majority of household plastics.[3] In nature, this compound is found in the minerals anatase, brookite, and rutile.[18] Paint made with titanium dioxide does well in severe temperatures, is somewhat self-cleaning, and stands up to marine environments.[3] Pure titanium dioxide has a very high index of refraction and an optical dispersion higher than diamond.[2]
Recently, it has been put to use in air purifiers (as a filter coating), or in film used to coat windows on buildings which when exposed to UV light (either solar or man-made) and moisture in the air produces reactive redox species like hydroxyl radicals that can purify the air or keep window surfaces clean.[34]
[edit] Aerospace and Marine
Because of its high tensile strength for its density,[6] high corrosion resistance,[2] and ability to withstand moderately high temperatures without creeping, titanium alloys are used in aircraft, armor plating, naval ships, spacecraft, and missiles.[3][2] For these applications, titanium alloyed with aluminum, vanadium, and other elements is used for a variety of components including critical structural parts, fire walls, landing gear, exhaust ducts (helicopters) and hydraulic systems. In fact, about two thirds of all titanium metal produced is used in aircraft engines and frames.[20] An estimated 58 tons are used in the Boeing 777, 43 in the 747, 18 in the 737, 24 in the Airbus A340, 17 in the A330 and 12 in the A320. The A380 may use 77 tons, including about 11 tons in the engines.[35] In engine applications, titanium is used for rotors, compressor blades, hydraulic system components and nacelles. The titanium 6AL-4V alloy accounts for almost 50% of all alloys used in aircraft applications. .[36]
Due to its high corrosion resistance to sea water, titanium is used to make propeller shafts and rigging and in the heat exchangers of desalination plants;[2] in heater-chillers for salt water aquariums, fishing line and leader, and diver knives as well. Titanium is used to manufacture the housings and other components of ocean-deployed surveillance and monitoring devices for scientific and military use.
[edit] Industrial
Welded titanium pipe and process equipment (heat exchangers, tanks, process vessels, valves) are used in the chemical and petrochemical industries primarily for corrosion resistance. Specific alloys are used in downhole and nickel hydrometallurgy applications due to their high strength (titanium Beta C) or corrosion resistance or combination of both. The pulp and paper industry uses titanium in process equipment exposed to corrosive media such as chlorine (in the bleachery).[37] Other applications include: ultrasonic welding, wave soldering,[38] and sputtering targets.[39]
[edit] Consumer and Architectural
Titanium metal is used in automotive applications, particularly in automobile or motorcycle racing, where weight reduction is critical while maintaining high strength and rigidity. The metal is generally too expensive to make it marketable to the general consumer market, other than high end products. Late model Corvettes have been available with titanium exhausts,[40] and racing bikes are frequently outfitted with titanium mufflers. Other automotive uses include piston rods and hardware (bolts, nuts, etc.).
Titanium is used in many sporting goods; tennis rackets, golf clubs, lacrosse stick shafts; cricket, hockey, lacrosse, and football helmet grills, and bicycle frames and components. Titanium alloys are also used in spectacle frames. This results in a rather expensive, but highly durable and long lasting frame which is light in weight and causes no skin allergies. Many backpackers use titanium equipment, including cookware, eating utensils, lanterns and tent stakes. Though slightly more expensive than traditional steel or aluminium alternatives, these titanium products can be significantly lighter without compromising strength. Titanium is also favored for use by farriers, since it is lighter and more durable than steel when formed into horseshoes. Titanium horseshoes can be found in horse racing, and are used by many Amish horse owners, who rely entirely on horse-drawn carriages for transportation.
Titanium has occasionally been used in architectural applications: the 120-foot (40 m) memorial to Yuri Gagarin, the first man to travel in space, in Moscow, is made of titanium for the metal's attractive color and association with rocketry.[41] The Guggenheim Museum Bilbao and the Cerritos Millennium Library were the first buildings in Europe and North America, respectively, to be sheathed in titanium panels. Other construction uses of titanium sheathing include the Frederic C. Hamilton Building in (Denver, Colorado).[42]
[edit] Medical
Because it is biocompatible (non-toxic and is not rejected by the body), titanium is used in a gamut of medical applications including surgical implements and implants, such as hip balls and sockets (joint replacement) that can stay in place for up to 20 years. Titanium has the inherent property to osseointegrate, enabling use in dental implants that can remain in place for over 30 years. This property is also useful for orthopedic implant applications.[8]
Since titanium is non-ferromagnetic, patients with titanium implants can be safely examined with magnetic resonance imaging (convenient for long-term implants). Preparing titanium for implantation in the body involves subjecting it to a high-temperature plasma arc which removes the surface atoms, exposing fresh titanium that is instantly oxidized.[8] Titanium is also used for the surgical instruments used in image-guided surgery, as well as wheelchairs, crutches, and any other product where high strength and low weight are important.
Its inertness and ability to be attractively colored makes it a popular metal for use in body piercing.[43] Titanium may be anodized to produce various colors.[44] A number of artists work with titanium to produce artworks such as sculptures, decorative objects and furniture.
[edit] Compounds
The +4 oxidation state dominates in titanium chemistry, but compounds in the +3 oxidation state are also common. Because of this high oxidation state, many titanium compounds have a high degree of covalent bonding.
Star sapphires and rubies get their asterism from the titanium dioxide impurities present in them.[8] Titanates are compounds made with titanium dioxide. Barium titanate has piezoelectric properties, thus making it possible to use it as a transducer in the interconversion of sound and electricity.[6] Esters of titanium are formed by the reaction of alcohols and titanium tetrachloride and are used to waterproof fabrics.[6]
Titanium nitride (TiN) is often used to coat cutting tools, such as drill bits. It also finds use as a gold-coloured decorative finish, and as a barrier metal in semiconductor fabrication.
Titanium tetrachloride (titanium(IV) chloride, TiCl4, sometimes called "Tickle") is a colourless liquid which is used as an intermediate in the manufacture of titanium dioxide for paint. It is widely used in organic chemistry as a Lewis acid, for example in the Mukaiyama aldol condensation. Titanium also forms a lower chloride, titanium(III) chloride (TiCl3), which is used as a reducing agent.
Titanocene dichloride is an important catalyst for carbon-carbon bond formation. Titanium isopropoxide is used for Sharpless epoxidation. Other compounds include; titanium bromide (used in metallurgy, superalloys, and high-temperature electrical wiring and coatings) and titanium carbide (found in high-temperature cutting tools and coatings).[3]
[edit] Isotopes
Naturally occurring titanium is composed of 5 stable isotopes; 46Ti, 47Ti, 48Ti, 49Ti and 50Ti with 48Ti being the most abundant (73.8% natural abundance). Eleven radioisotopes have been characterized, with the most stable being 44Ti with a half-life of 63 years, 45Ti with a half-life of 184.8 minutes, 51Ti with a half-life of 5.76 minutes, and 52Ti with a half-life of 1.7 minutes. All of the remaining radioactive isotopes have half-lives that are less than 33 seconds and the majority of these have half-lives that are less than half a second.[7]
The isotopes of titanium range in atomic weight from 39.99 u (40Ti) to 57.966 u (58Ti). The primary decay mode before the most abundant stable isotope, 48Ti, is electron capture and the primary mode after is beta emission. The primary decay products before 48Ti are element 21 (scandium) isotopes and the primary products after are element 23 (vanadium) isotopes.[7]
[edit] Precautions
Titanium is non-toxic even in large doses and does not play any natural role inside the human body. An estimated 0.8 milligrams of titanium is ingested by humans each day but most passes through without being absorbed. It does, however, have a tendency to bio-accumulate in tissues that contain silica. An unknown mechanism in plants may use titanium to stimulate the production of carbohydrates and encourage growth. This may explain why most plants contain about 1 part per million (ppm) of titanium, food plants have about 2 ppm and horsetail and nettle contain up to 80 ppm.[8]
As a powder or in the form of metal shavings, titanium metal poses a significant fire hazard and, when heated in air, an explosion hazard. Water and carbon dioxide-based methods to extinguish fires are ineffective on burning titanium; Class D dry powder fire fighting agents must be used instead.[3]
Even bulk titanium metal is susceptible to fire, when it is heated to its melting point. A number of titanium fires occur during breaking down devices containing titanium parts with cutting torches.
Titanium can catch fire when a fresh, non-oxidized surface gets in contact with liquid oxygen. Such surface can appear when an oxidized surface is struck with a hard object, or when a mechanical strain causes an emergence of a crack. This poses a limit for use of titanium in liquid oxygen systems in eg. aerospace industry.
Salts of titanium are often considered to be relatively harmless but its chlorine compounds, such as TiCl2, TiCl3 and TiCl4, have unusual hazards. The dichloride takes the form of pyrophoric black crystals, and the tetrachloride is a volatile fuming liquid. All of titanium's chlorides are corrosive.
[edit] See also
[edit] References
- ^ a b c "Titanium". Encyclopædia Britannica Concise. (2005).
- ^ a b c d e f g h i j k l m Titanium. Los Alamos National Laboratory (2004). Retrieved on 2006-12-29.
- ^ a b c d e f g h i j k Krebs, Robert E. (2006). The History and Use of Our Earth's Chemical Elements: A Reference Guide (2nd edition). Westport, CT: Greenwood Press. ISBN 0313334382.
- ^ Matthew J. Donachie, Jr. (1988). TITANIUM: A Technical Guide. Metals Park, OH: ASM International, p.11. ISBN 0871703092.
- ^ a b c d e f g h i j k l m Barksdale, Jelks (1968). The Encyclopedia of the Chemical Elements. Skokie, Illinois: Reinhold Book Corporation, 732-38 "Titanium". LCCCN 68-29938.
- ^ a b c d e f g h "Titanium". Columbia Encyclopedia (6th edition). (2000 – 2006). New York: Columbia University Press. ISBN 0787650153.
- ^ a b c Barbalace, Kenneth L. (2006). Periodic Table of Elements: Ti - Titanium. Retrieved on 2006-12-26.
- ^ a b c d e f g h i j Emsley, John (2001). Nature's Building Blocks: An A-Z Guide to the Elements. Oxford: Oxford University Press, pp. 451 – 53. ISBN 0-19-850341-5.
- ^ Origins of the Element Names: Names Derived from Mythology or Superstition
- ^ van Arkel, A. E.; de Boer, J. H. (1925). "Preparation of pure titanium, zirconium, hafnium, and thorium metal". Z. Anorg. Allg. Chem. 148: 345 – 50.
- ^ Yanko, Eugene; Omsk VTTV Arms Exhibition and Military Parade JSC (2006). Submarines: general information. Retrieved on 2006-12-26.
- ^ Stainless Steel World. "VSMPO Stronger Than Ever", KCI Publishing B.V., July/August 2001, pp. 16–19. Retrieved on 2007-01-02.
- ^ NATIONAL MATERIALS ADVISORY BOARD, Commission on Engineering and Technical Systems (CETS), National Research Council (1983). Titanium: Past, Present, and Future. Washington, DC: national Academy Press, R9. NMAB-392.
- ^ Titanium Metals Corporation. Answers.com. Encyclopedia of Company Histories,. Answers Corporation (2006). Retrieved on 2007-01-02.
- ^ Defense National Stockpile Center (2006). Strategic and Critical Materials Report to the Congress. Operations under the Strategic and Critical Materials Stock Piling Act during the Period October 2004 through September 2005. United States Department of Defense, § 3304.
- ^ Bush, Jason. "Boeing's Plan to Land Aeroflot", BusinessWeek, 2006-02-15. Retrieved on 2006-12-29.
- ^ DuPont (2006-12-09). U.S. Defense Agency Awards $5.7 Million to DuPont and MER Corporation for New Titanium Metal Powder Process. Retrieved on 2006-12-26.
- ^ a b c d e f "Titanium". Encyclopædia Britannica. (2006). Retrieved on 2006-12-29.
- ^ Matthew J. Donachie, Jr. (1988). TITANIUM: A Technical Guide. Metals Park, OH: ASM International, Appendix J, Table J.2. ISBN 0871703092.
- ^ a b c Emsley, John (2001). Nature's Building Blocks: An A-Z Guide to the Elements. Oxford: Oxford University Press, 455. ISBN 0-19-850341-5.
- ^ Casillas, N.; Charlebois, S.; Smyrl, W. H.; White, H. S. (1994). "Pitting Corrosion of Titanium". J. Electrochem. Soc. 141 (3): 636 – 42. Abstract
- ^ a b "Titanium". Microsoft Encarta. (2005). Retrieved on 2006-12-29.
- ^ Cordellier, Serge; Didiot, Béatrice (2004). L'état du monde 2005: annuaire économique géopolitique mondial. Paris: La Découverte.
- ^ Matthew J. Donachie, Jr. (1988). TITANIUM: A Technical Guide. Metals Park, OH: ASM International, Chapter 4. ISBN 0871703092.
- ^ Chen, George Zheng; Fray, Derek J.; Farthing, Tom W. (2000). "Direct electrochemical reduction of titanium dioxide to titanium in molten calcium chloride". Nature 407: 361 – 64. DOI:10.1038/35030069. Abstract
- ^ Matthew J. Donachie, Jr. (1988). TITANIUM: A Technical Guide. Metals Park, OH: ASM International, p.16, Appendix J. ISBN 0871703092.
