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

Abstract

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.

Keywords

• sic
• microwave processing
• grain growth
• crystal structure
• sheet carbon source