Study on mechanisms of microwave synthesis of SiC crystal from sheet carbon source

Needle-like SiC whiskers were synthesised by microwave heating using graphite sheets and tetraethoxysilane (TEOS) as raw materials. It was found that SiC powder could be synthesised at 1000?C for 10min, lower than that of samples made from a granular C source. Furthermore, the heating rate of the samples made with graphite sheets was higher than that of a granular C source. The main morphology of the SiC whiskers was needle-like, which appeared when samples were heated at 1200?C for 10min. Size of the SiC whiskers made with graphite sheets was more uniform than that of a granular C source, which was attributed to the 2D thermal effect. Moreover, the size and the amount of the SiC whiskers increased as the heating temperature increased from 1200 to 1400?C for 10min. The SiC whiskers were oxidised and decomposed into SiC particles when heated to 1500?C for 10min and only SiC particles existed when longer holding times were used.