REFRACTORY METALS TUNGSTEN, MOLYBDENUM AND TANTALUM.

Tungsten, molybdenum and tantalum with their alloys and compound materials are for the most part still made by powdermetallurgical methods. Although modern fusion methods have been developed which make it possible in many cases to produce these metals by melting instead of by sintering, many materials used in the electronics industry can only be produced by powder metallurgy. Examples are doped refractory metals such as NS-tungsten, HT-molybdenum, thoriated tungsten, porous tungsten for emission cathodes, and porous tantalum for electrolytic capacitors.