Synthesis of submicrometer-sized β-SiC particles from the precursors composed of exfoliated graphite and silicone Original Research Article

Utilizing micro-spaces of exfoliated graphite (EG), a process to synthesize fine β-SiC particles was developed. Two types of low molecular weight silicone and a catalyst were impregnated into EG by sorption, and then heated in air to cure the compounds. Formed precursors were black flakes of a few millimeters in diameter. Only by the heat treatment of precursors at 1500 °C for 5 h or at 1550–1600 °C for 1 h in Ar, β-SiC of a few tens to hundreds nanometers in size was obtained with the yield around 40 mass%. In the present process, EG play two important roles; one is as reaction spaces and the other is as a reductant that functions at elevated temperatures. Initially the cured silicone is coating the graphite sheets of EG as thin films of less than 1 μm, and above 1300 °C they start to decompose and form small particles of a few tens to 100 nm in diameter on the graphite sheets. These intermediate particles are composed of the Si–C–O composites and SiO2 and they spontaneously decompose to β-SiC from around 1400 °C, and between 1400 and 1500 °C the reduction of remaining Si–C–O intermediates by graphite sheets occur and form well-crystallized fine β-SiC particles. The process is simple and raw materials are not expensive so that it is promising for industrial applications.