RI 7247 Preparation Of Tungsten Carbide By Electrodeposition

The preparation of tungsten carbide by molten-salt electrolysis was investigated. Sodium tungstate in the electrolyte and carbon from the graphite anode were the source materials, Optimum results were obtained with an electrolyte consisting of 83 mole-percent sodium chloride and 5.7 mole-percent each of sodium tungstate, sodium metaborate, and sodium hydroxide; a temperature of 1,000° to 1,025° C; an anode current density of 37 amp/dm2 or less; and an initial cathode current density of 150 amp/dm2. The yield was approximately 0.45 g/amp hr. The electrolytic tungsten carbide product contained approximately 5.4 weight-percent combined carbon as compared to 6.1 weight-percent for pure tungsten carbide. Microhardness of the electrolytic tungsten carbide, determined with a 50-gram load, varied from 3,480 to 3,970 dph. The material was friable and could be ground in a laboratory ball mill to less than 400-mesh particle size.