抄録
A process for production of fine WC powders using Co3O4 as an additive was investigated. The mixed powder of WO3, carbon black and 0.4 to 6.25%Co3O4 was reduced and carburized in H2 at various temperatures. This report deals with the result of the examination on the operating conditions and the particle size of the obtained WC.
From the chemical analysis of combined carbon contents of the products and identification of the compounds by X-ray analysis, it was found that the mixed powder containing more than 1.6%Co3O4 could be carburized at 900°C. When the Co3O4 content is less than 1.6%, the lower the Co3O4 content the higher the carburization temprature, and the effect of Co addition was almost negligible at less than 0.4%Co3O4. The WC particle size obtained became coarser as the degree of reduction, carburization temperature and Co3O4 content increased. The particle size of more than about 0.6 μm could be controlled by regulating these three factors. Although in this process the WC was carburized at a much lower temperature than in the usual process, where WC was prepared by the reaction between W and C, its grain size of WC determined by X-ray diffraction was comparatively large and became larger with increasing Co3O4 content of the mixed powder.
