TUNGSTEN PROCESSING

preparation of the ore for use in various products. Tungsten exhibits a body-centred cubic (bcc) crystal lattice. It has the highest melting point of all metals, 3,410 C (6,170 F), and it has high conductivity for electricity. Owing to this unique combination of properties, it is used extensively as filaments for incandescent lamps, as electric contacts, and as electron emitters for electronic devices. Tungsten also has found wide application as an alloying element for tool steels and wear-resistant alloys. Tungsten carbides are used for cutting tools and hard-facing materials owing to their hardness and resistance to wear. The metal is brittle at room temperature but ductile and strong at elevated temperatures. Its alloys are employed in rocket-engine nozzles and other aerospace applications. Additional reading Comprehensive and up-to-date information on many aspects of metallurgy, individual metals, and alloys can be found in convenient reference-form arrangement in the following works: Metals Handbook, 9th ed., 17 vol. (197889), a massive and detailed source prepared under the direction of the American Society for Metals, with a 10th edition that began publication in 1990; Herman F. Mark et al. (eds.), Encyclopedia of Chemical Technology, 3rd ed., 31 vol. (197884), formerly known as Kirk-Othmer Encyclopedia of Chemical Technology, with a 4th edition begun in 1991; and its European counterpart, the first English-language edition of a monumental German work, Ullmann's Encyclopedia of Industrial Chemistry, 5th, completely rev. ed., edited by Wolfgang Gerhartz et al. (1985 ). The Editors of the Encyclopdia Britannica Stephen W.H. Yin and Chun T. Wang, Tungsten: Sources, Metallurgy, Properties, and Applications (1979), provides a comprehensive survey of mineralogy, mining, extraction, reduction, chemical and physical properties, and industrial uses of the metal. A convenient single source of reference information on all the refractory metals is Clifford A. Hampel, Rare Metals Handbook, 2nd ed. (1961, reprinted 1971). Chun Tsin Wang Alexander Sutulov