Tungsten, metallurgy

Incandescent Lamps, Electronic Tubes, and Resistance Elements. Articles fashioned in any form from molybdenum and tungsten usually fall within the bounds of powder metallurgy. These metals normally are first produced as a powder. Both molybdenum and tungsten are used as targets in x-ray tubes, for stmctural shapes such as lead and grid wires in electron tubes, and as resistance elements in furnaces. 

Consolidation. Because of its high melting point, tungsten is usually processed by powder metallurgy techniques (see Powder metallurgy). Small quantities of rod are produced by arc or electron-beam melting. 

T. WHken, C. Wert,J. Woodhouse, and W. Morcom, "Reduction of Blue Tungsten Oxide," in H. H. Hausner and P. V. Taubenblat, eds.. Modem Developments in Powder Metallurgy, Vol. 9, Plenum Press, New York, 1977, pp. 161—169. 

The basic corrosion behaviour of stainless steels is dependent upon the type and quantity of alloying. Chromium is the universally present element but nickel, molybdenum, copper, nitrogen, vanadium, tungsten, titanium and niobium are also used for a variety of reasons. However, all elements can affect metallurgy, and thus mechanical and physical properties, so sometimes desirable corrosion resisting aspects may involve acceptance of less than ideal mechanical properties and vice versa. 

Some of these reactions are employed in the metallurgy of oxide ores, for example, in the commercial production of tungsten metal. WO3 in Eq. 5.4 is reduced to the free metal by hydrogen. 

In preparing solid platinum from its powder, Wollaston foreshadowed modern methods of powder metallurgy, by which the powders of refractory metals, such as tungsten, molybdenum, tantalum, and columbium, can be fabricated into useful articles (84, 86). 

Maroglou A, Nienow AW. Fluidized bed granulation technology and its application to Tungsten Carbide. Powder Metallurgy 1986 29(4). 

Maroglou, A., and Nienow, A. W. Fluidized bed Granulation Technology and its application to tungsten carbide. Powder Metallurgy 29(4) 1986. 

In metallurgy, niobium is classified as a refractory metal, along with tungsten, tantalum, and molybdenum. A comparison of the four metals is given in the accompanying table. 

Sintering of tungsten is activated by addition of small amounts of Pd, Ni, Fe, or other elements. Data are for 1 h at the indicated temperatures. Reprinted with permission from Powder Metallurgy Science, 1984, Metal Powder Industries Federation, 105 College Road East, Princeton, New Jersey, USA. 

Pink, E. and L. Bartha (eds) (1989) The Metallurgy of DopedINon-Sag Tungsten, Elsevier Applied Science, London. 

Prokudina, V.K., Kalikhman, V.L., Golubnichaya, A.A., Borovinskaya, I.P. and Merzhanov, A.G., Synthetic Molybdenum and Tungsten Disulfides, Soviet Powder Metallurgy and Metal Ceramics, 17, 450, (1978). 

Kiparisov, S.S., Shvetsova, G.A., Lobova, T.A., Sergeeva, L.M., Pimenova, A.Z. and Volodina, G.A., Structure and Properties of a Self-Lubricating Material Based on Tungsten Diselenide, Soviet Powder Metallurgy and Metal Ceramics, 17, 399, (1978). 

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