Synthesis of ultrafine 3C–SiC powder by sol–gel and carbothermal reduction processing

This study focuses on the synthesis of ultra-fine 3C silicon carbide (β-SiC) powder using a sol–gel method combined with carbothermal reduction. Tetraethyl orthosilicate (TEOS) was employed as the silicon source, while dextrin, sucrose and glucose were tested as carbon sources. The effects of key synthesis parameters – calcination temperature, insulation time and carbon-to-silicon (C/Si) ratio – on the formation of SiC were systematically investigated. The synthesised powders were characterised using X-ray diffraction (XRD) to determine phase composition, field emission scanning electron microscopy (FE-SEM) to analyse microstructure and morphology and energy dispersive spectroscopy (EDS) to assess elemental composition and oxygen content. Optimal synthesis conditions were achieved using dextrin as the carbon source with a C/Si ratio of 2. Under flowing argon (Ar) protection, the precursor was fully converted to SiC after calcination at 1500 °C for 180 minutes. The final product exhibited a pure SiC phase with no detectable impurities. The powder had an average crystallite size of 32 nm, a sphericity of 0.85, and an oxygen content of approximately 4%. This work demonstrates the feasibility of producing high-purity, ultra-fine SiC powder with controlled properties through a sol–gel and carbothermal reduction approach, highlighting the importance of precursor selection and process optimisation.