Titanium

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Titanium
Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous,corrosion-resistant (including sea water, aqua regia and chlorine) transition metal with a silver color.
Titanium was discovered in Cornwall, Great Britain, by William Gregor in 1791 and named by Martin HeinrichKlaproth for the Titans of Greek mythology. The element occurs within a number of mineral deposits, principally rutile and ilmenite, which are widely distributed in the Earth's crust and lithosphere, and it is found in almost all living things, rocks, water bodies, and soils. The metal is extracted from its principal mineral ores via the Kroll process or theHunter process. Its most commoncompound, titanium dioxide, is a popular photocatalyst and is used in the manufacture of white pigments. Other compounds include titanium tetrachloride (TiCl4), a component of smoke screens and catalysts; and titanium trichloride (TiCl3), which is used as a catalyst in the production of polypropylene. Titanium can be alloyed with iron, aluminium, vanadium, molybdenum, among other elements, to produce stronglightweight alloys for aerospace (jet engines, missiles, and spacecraft), military, industrial process (chemicals and petro-chemicals, desalination plants, pulp, and paper), automotive, agri-food, medical prostheses, orthopedic implants, dental and endodontic instruments and files, dental implants, sporting goods, jewelry, mobile phones, and other applications. The two most useful properties ofthe metal form are corrosion resistance and the highest strength-to-weight ratio of any metal. In its unalloyed condition, titanium is as strong as some steels, but 45% lighter. There are two allotropic forms [ and five naturally occurring isotopes of this element, 46Ti through50Ti, with 48Ti being the most abundant (73.8%). Titanium's properties are chemically and physically similar to zirconium,because both of them have the same number of valence electrons and are in the same group in the periodic table.

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Characteristics
Physical properties
A metallic element, titanium is recognized for its high strength-to-weight ratio.[7] It is a strong metal with low density that is quite ductile (especially in anoxygen-free environment),lustrous, and metallic-white in color. The relatively high melting point (more than 1,650 °C or 3,000 °F) makes it useful as arefractory metal. It is paramagnetic and has fairly low electrical and thermal conductivity.
Commercial (99.2% pure) grades of titanium have ultimate tensile strength of about 63,000 psi (434 MPa), equal to that of common, low-grade steel alloys, but are 45% lighter. Titaniumis 60% more dense than aluminium, but more than twice as strong as the most commonly used 6061-T6 aluminium alloy. Certain titanium alloys (e.g., Beta C) achieve tensile strengths of over 200,000 psi (1,400 MPa).
The metal is a dimorphic allotrope whose hexagonal alpha form changes into a body-centered cubic (lattice) β form at 882 °C (1,620 °F).[11] The specific heat of the alpha form increasesdramatically as it is heated to this transition temperature but then falls and remains fairly constant for the β form regardless of temperature.[11] Similar to zirconium and hafnium, an additional omega phase exists, which is thermodynamically stable at high pressures, but is metastable at ambient pressures. This phase is usually hexagonal (ideal) or trigonal (distorted) and can be viewed asbeing due to a soft longitudinal acoustic phonon of the β phase causing collapse of (111) planes of atoms.
Chemical properties
The most noted chemical property of titanium is its excellent resistance to corrosion; it is almost as resistant asplatinum, capable of withstanding attack by dilute sulfuric acid and hydrochloric acid as well as chlorine gas, chloride solutions, and most organic...