Study on influencing factors and mechanism of high-quality tungsten carbide nanopowders synthesized via carbothermal reduction

Highlights: • WC nanopowders were synthesized by carbothermal reduction method. • Carbon source and temperature have important influence on the process and mechanism of carbothermal reduction. • The nucleation and growth mechanism of WC nanoparticles has been investigated. • The method is potential to be used for other nano-sized transition metal carbide/ nitride. -- Abstract: In this study, high-quality WC powders with 100 nm were synthesized using a simple and efficient carbothermal reduction method. The effects of carbon source and temperature on the synthesis process, nucleation and growth mechanism of WC nanopowders were investigated in detailed. The results show that acetylene black with small particle size and good dispersion is the optimal carbon source to prepare WC nanopowders. The uniform precursor synthesized by acetylene black can significantly increase the contact probability of WO₃ and C particles, greatly reduce the activation energy, and effectively improve the reaction efficiency during subsequent carbothermal reduction process. Moreover, the formation temperatures of WC are reduced to 1000 °C compared with other three carbon source. Further increasing carbothermal reduction temperature can provide the driving force of diffusing atoms, which promotes the carbothermal reduction reaction, but also significantly increases the diffusion rate of grain boundary resulting in rapid grain growth.