Tungsten

Tungsten has the highest melting point of all metals, 1650°C, and the highest tensile strength (resists pulling apart).   It resists corrosion exceptionally well.   Its thermal expansion is about the same as borosilicate glass, so it is used for glass-to-metal seals.   In 1909, William David Coolidge, an American physicist, perfected a method of drawing tungsten into fine wires, which enabled inventors like Thomas A. Edison, to use it as a long-lasting electric lamp filaments and others to use it in radio tubes and other devices. ^{Asimov 506}.   Tungsten and its alloys are used for electric lamp filaments, TV monitors, metal evaporation work, electrical contact points, X-ray targets, windings and heating elements in electric furnaces, high-speed tool steels (there, it is so wear-resistant that it increases the productivity of machinist's work 5 times), and other high-temperature applications.   Tungsten carbide is important to the metal-working, mining, and petroleum industries where its hardness and wear-resistance makes it an excellent material for tools.   Calcium and magnesium tungstates are used in fluorescent lighting.   Tungsten salts are used in the chemical and tanning industries.   Tungsten disulfide is a dry, high-temperature lubricant and tungsten bronzes and other tungsten compounds are used in paints. ^{Lide 4-31}

Tungsten was discovered in 1783 by Don Fausto D'Eluyar, a Spanish mineralogist, who called it wolfram, ^{Asimov 259} or Peter Woulfe in 1779.^{Lide 4-31}   The de Elhuyar brothers obtained the metal by reducing tungsten acid with charcoal.   Tungsten is found in wolframite, (Fe,Mn)WO₄, scheelite (free tungsten), CaWO₄, huebnerite, MnWO₄, and ferberite, FeWO₄.   Tungsten is obtained commercially by reducing tungsten oxide with hydrogen or carbon. ^{Lide 4-31}