Titanium is capable of withstanding attack by dilute sulfuric and hydrochloric acids, chloride solutions, and most organic acids. This layer gives titanium excellent resistance to corrosion, almost equivalent to platinum. When it first forms, this protective layer is only 1–2 nm thick but it continues to grow slowly, reaching a thickness of 25 nm in four years. Like aluminium and magnesium, the surface of titanium metal and its alloys oxidize immediately upon exposure to air to form a thin non-porous passivation layer that protects the bulk metal from further oxidation or corrosion. Pourbaix diagram for titanium in pure water, perchloric acid, or sodium hydroxide The specific heat of the α form increases dramatically as it is heated to this transition temperature but then falls and remains fairly constant for the β form regardless of temperature. The metal is a dimorphic allotrope of an hexagonal α form that changes into a body-centered cubic (lattice) β form at 882 ☌ (1,620 ☏). Like steel structures, those made from titanium have a fatigue limit that guarantees longevity in some applications. Machining requires precautions, because the material can gall unless sharp tools and proper cooling methods are used. Titanium is not as hard as some grades of heat-treated steel it is non-magnetic and a poor conductor of heat and electricity. However, titanium loses strength when heated above 430 ☌ (806 ☏). Certain titanium alloys (e.g., Beta C) achieve tensile strengths of over 1,400 MPa (200,000 psi). Titanium is 60% denser than aluminium, but more than twice as strong as the most commonly used 6061-T6 aluminium alloy. Ĭommercially pure (99.2% pure) grades of titanium have ultimate tensile strength of about 434 MPa (63,000 psi), equal to that of common, low-grade steel alloys, but are less dense. Titanium is superconducting when cooled below its critical temperature of 0.49 K. It is paramagnetic and has fairly low electrical and thermal conductivity compared to other metals. The relatively high melting point (1,668 ☌ or 3,034 ☏) makes it useful as a refractory metal. It is a strong metal with low density that is quite ductile (especially in an oxygen-free environment), lustrous, and metallic-white in color. Characteristics Physical propertiesĪs a metal, titanium is recognized for its high strength-to-weight ratio. There are two allotropic forms and five naturally occurring isotopes of this element, 46Ti through 50Ti, with 48Ti being the most abundant (73.8%).
In its unalloyed condition, titanium is as strong as some steels, but less dense.
The two most useful properties of the metal are corrosion resistance and strength-to-density ratio, the highest of any metallic element. Titanium can be alloyed with iron, aluminium, vanadium, and molybdenum, among other elements, to produce strong, lightweight alloys for aerospace ( jet engines, missiles, and spacecraft), military, industrial processes (chemicals and petrochemicals, desalination plants, pulp, and paper), automotive, agriculture (farming), medical prostheses, orthopedic implants, dental and endodontic instruments and files, dental implants, sporting goods, jewelry, mobile phones, and other applications. Other compounds include titanium tetrachloride (TiCl 4), a component of smoke screens and catalysts and titanium trichloride (TiCl 3), which is used as a catalyst in the production of polypropylene. The most common compound, titanium dioxide, is a popular photocatalyst and is used in the manufacture of white pigments. The metal is extracted from its principal mineral ores by the Kroll and Hunter processes. The element occurs within a number of minerals, principally rutile and ilmenite, which are widely distributed in the Earth's crust and lithosphere it is found in almost all living things, as well as bodies of water, rocks, and soils. Titanium was discovered in Cornwall, Great Britain, by William Gregor in 1791 and was named by Martin Heinrich Klaproth after the Titans of Greek mythology. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion in sea water, aqua regia, and chlorine. Titanium is a chemical element with the symbol Ti and atomic number 22.
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