Effects of Mechanical Activation during the Synthesis of Tungsten Carbide Powders by Carbothermic Reduction of Tungsten Oxide

Abstract

In this work, the effects of mechanical milling on the extent of reduction were investigated to give an overview of potential improvements in the preparation of WC. A mixture of graphite and tungsten oxide (WO3) was mechanically milled together for 10 h. The as-milled powder and un-milled powder were investigated by thermal analysis, isothermal treatment, and X-ray diffraction to determine the effect of milling on the carbothermal reduction of WO3 to tungsten carbide (WC). The as-milled powder underwent a rapid reduction reaction at about 150°C lower than the un-milled powder. The reduction sequence to WC was illustrated to differ for the two powders. The milled powder showed complete reduction to WC in 1 h at 1215°C whereas the un-milled powder was incompletely reduced. Finally, WC powder was readily achieved by carbothermic reduction of mechanical activated WO3 and graphite, leaving its grains nano-sized.