titanium (for the mythological Titans), symbol Ti, chemical element, silvery gray metal of transition Group IVb of the periodic table, lightweight, high-strength, low-corrosion structural metal, used in alloy form for parts in high-speed aircraft. A compound of titanium and oxygen was discovered (1791) by the English chemist and mineralogist William Gregor and independently rediscovered (1795) and named by the German chemist Martin Heinrich Klaproth. Widely distributed and plentiful, titanium is the ninth most abundant element in the Earth’s crust, found combined in practically all rocks, sand, clay, and other soils. It is also present in plants and animals, natural waters and deep-sea dredgings, and meteorites and stars. The two prime commercial minerals are ilmenite and rutile. The metal was isolated in pure form (1910) by the New Zealand-born U.S. metallurgist Matthew A. Hunter by reducing titanium tetrachloride (TiCl4) with sodium in an airtight steel cylinder. After 1947 titanium changed from a laboratory curiosity to an important structural metal commercially produced by the Kroll process (magnesium reduction of the tetrachloride). In pure form titanium is ductile, about half as dense as iron and less than twice as dense as aluminum; it can be polished to a high lustre. The metal has a very low electrical and thermal conductivity and is paramagnetic (weakly responsive to a magnet). Two crystal structures exist: below 882° C (1,620° F), hexagonal close-packed (alpha); above 882° C, body-centred cubic (beta). Natural titanium consists of five stable isotopes from titanium-46 to titanium-SO. The importance of titanium is based on its ability to be alloyed with most metals and some nonmetals.

By alloying titanium, its tensile strength can be increased fivefold to 200,000 pounds per square inch (14,000 kilograms per square centimetre). Titanium has excellent corrosion resistance in many environments because of the formation of a passive oxide surface film. No noticeable corrosion of the metal has been found after exposure to seawater for over three years. Its combination of high strength, low density, and excellent corrosion resistance explains why titanium is used for many parts of aircraft, spacecraft, missiles, and ships. It is used in prosthetic devices also, because there is no reaction between titanium and fleshy tissues and bones. Titanium has also been utilized as a deoxidizer in steel and as an alloying addition in many steels to reduce grain size, in stainless steel to reduce carbon content, in aluminum to refine grain size, and in copper to produce hardening. Although at room temperatures titanium is resistant to tarnishing, at elevated temperatures it reacts with oxygen in the air. This is no detriment to the properties of titanium during forging or fabrication of its alloys; the oxide scale is removed after fabrication. In the liquid state, however, titanium is very reactive and reduces all known refractories. It exhibits three valences in compounds of the type TiO, Ti203, and Ti02. The -1-4 oxidation state the most stable as in the dioxide (TiOa, white pigment) and the tetrachloride (a liquid smoke-producing compound used for skywriting and smoke screens). atomic number 22 atomic weight 47.90 melting point 1,675° C (3,047° F) boiling point 3,260° C (5,900° F) specific gravity 4.5 (20° C) valence 2, 3, 4 electronic config. 2-8-10 2 or (Ar)3d24s2

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Author Resource BoxI live in Middlesex, UK. I am a researcher for a company which manufactures agricultural supplies to the farms in the countyside. Married with 2 children.Read Ben Heus Profile