Size-controlled synthesis of high-purity tungsten carbide powders via a carbothermic reduction–carburization process

In this paper, a novel method is proposed to synthesize high-purity tungsten carbide (WC) powders with different sizes via carbothermic reduction of yellow tungsten trioxide (WO3) followed by the further carbonization process. The effects of the reaction temperature, reaction time and C/WO3 molar ratio on the phase transition and morphology evolution of the products are investigated in detail. The results reveal that the morphology of the final products is mainly determined at the carbothermic reduction stage, and the particle size of WC is significantly affected by the C/WO3 molar ratio and reaction temperature. It can be concluded from experimental results that particle size of WC increased with the increased of temperature, but decreased with increased of C/WO3 molar ratio. When the C/WO3 molar ratio is 2.7–3.5, the single phase WC with a size of 178–825 nm can be obtained after further carbonization at 1200 °C. •A carbothermic reduction-carbonization process was proposed to prepare ultrafine WC powders.•Particle sizes of WC powders are controllable in the range of 178–825 nm.•Particle size of WC is significantly affected by C/WO3 molar ratio and temperature.•Carbon content of final products is very close to the theoretical value of tungsten carbide.