The morphology regulating effect of cobalt acetate on the vacuum carbothermal synthesis of β-SiC powder

Abstract

SiC nanoparticles have significant applications in ceramics and semiconductors; however, the prohibitive production cost and difficulty in managing the morphology during large-scale synthesis are major issues. In this study, uniform β-SiC nanoparticles were synthesised via vacuum carbothermal reduction using a small amount of cobalt acetate as the catalyst. The impact of the cobalt acetate concentration, reaction temperature, and its holding time on the morphological characteristics of the SiC nanoparticles was investigated. The results demonstrated that SiC whiskers were initially produced during vacuum carbothermal reduction, and during the next stages, the shape of the SiC whiskers was regulated by the presence of trace Co. SiC nanoparticles with no whiskers, no nanowires and homogeneous morphology was synthesised at 1300 °C held for 6 h using a Co-to-Si molar ratio of 0.68. Thermodynamic analysis of the Co-regulated SiC reaction process proposed that the disappearance of SiC whiskers and nanowires under vacuum might be due to the catalytic effect of Co on the “decomposition and re-nucleation” reaction mechanism.