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Titanium
Titanium is a chemical element in the periodic table that has the symbol Ti and atomic number 22. It is a light, strong, lustrous, corrosion-resistant (including resistance to sea water and chlorine) transition metal with a white-silvery-metallic color. Titanium is used in strong light-weight alloys (most notably with iron and aluminum) and its most common compound, titanium dioxide, is used in white pigments.
This element occurs in numerous minerals with the main sources being rutile and ilmenite, which are widely distributed over the Earth. There are two allotropic forms and five naturally-occurring isotopes of this element; Ti-46 through Ti-50 with Ti-48 being the most abundant (73.8%). One of titanium's most notable characteristic is that it is as strong as steel but is less than half its weight. Titanium's properties are chemically and physically similar to zirconium
Notable characteristics
Titanium is well known for its excellent corrosion resistance (almost as resistant as platinum), being able to withstand attack by acids, moist chlorine gas, and by common salt solutions. Pure titanium is not soluble in water but is soluble in concentrated acids. A metallic element, it is also well-known for its high strength-to-weight ratio. It is a light, strong metal with low density (40% as dense as steel) that, when pure, is quite ductile (especially in an oxygen-free environment), easy to work, lustrous, and metallic-white in color. The relatively high melting point of this element makes it useful as a refractory metal. Titanium is as strong as steel, but 45% lighter; it is 60% heavier than aluminum, but twice as strong. These properties make titanium very resistant to the usual kinds of metal fatigue.
This metal forms a passive but protective oxide coating (leading to corrosion-resistance) when exposed to elevated temperatures in air but at room temperatures it resists tarnishing. The metal, which burns when heated in air 610° C or higher (forming titanium dioxide) is also one of the only elements that burn in pure nitrogen gas (it burns at 800° C and forms titanium nitride). Titanium is resistant to dilute sulfuric and hydrochloric acid, along with chlorine gas, chloride solutions, and most organic acids. It is paramagnetic (weakly attracted to magnets) and has a very low electrical and thermal conductivity.
Experiments have shown that natural titanium becomes very radioactive after it is bombarded with deuterons, emitting mainly positrons and hard gamma rays. The metal is a dimorphic allotrope with the hexagonal alpha form changing into the cubic beta form very slowly at around 880°C. When it is red hot the metal combines with oxygen, and when it reaches 550°C it combines with chlorine. It also reacts with with the other halogens and absorbs hydrogen
Applications
Approximately 95% of titanium is consumed in the form of titanium dioxide (TiO2), an intensely white permanent pigment with good covering power in paints, paper, and plastics. Paints made with titanium dioxide are excellent reflectors of infrared radiation and are therefore used extensively by astronomers and in exterior paints. It is also used as a strengthening filler in paper and cement and in gemstones.
Because of its very high tensile strength (even at high temperatures), light weight, extraordinary corrosion resistance, and ability to withstand extreme temperatures, titanium alloys are principally used in aircraft, armor plating, naval ships, spacecraft and missiles. It is used in steel alloys to reduce grain size and as a deoxidizer but in stainless steel it is employed to reduce carbon content. Titanium is often alloyed with aluminium (to refine grain size), vanadium, copper (to harden), iron, manganese, molybdenum and with other metals.
Its vanadium alloy is used to make the outer skin of aircraft, to make fire walls, landing-gear, and hydraulic tubing. A typical commercial jet airplane contains 318 to 1134 kg (700 and 2500 lb) of titanium. Use of titanium in consumer products such as golf clubs, bicycles, laboratory equipment, wedding bands, and laptop computers are becoming more common.
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