Preparation of Ultrafine W Powder via H2 Reduction of Carbon-Containing WO3: Influences of Reduction Temperature and C/WO3 Molar Ratio

Ultrafine W powder is a key material for manufacturing high-performance W-based products. In this study, ultrafine W powder was prepared via the H₂ reduction of carbon-containing WO₃, and the parameters of reduction temperature (740-830 °C) and C/WO₃ molar ratio (0.5-2.5) were mainly considered. The results demonstrated that, with the increase in reduction temperature, the reaction rate gradually increased, while the particle size of W powder exhibited a trend showing an initial decrease and then increase, with a minimum value of 146 nm at 770 °C. The results also showed that, with the increase in C/WO₃ molar ratio, the reaction rate gradually decreased, while the particle size of W powder also first decreased and then increased, with its minimum value at a C/WO₃ molar ratio of 1.0. The reduction pathways of H₂ reduction of WO₃ to W was given as WO₃→WO_2.9→WO_2.72→WO₂→W. Due to the co-actions of nucleating agent and the synergistic reduction effect, the particle size of W powder obtained by reducing carbon-containing WO₃ was smaller than that obtained by reducing pure WO₃, and a possible reaction mechanism was proposed.