Preparation of silicon carbide coating by chemical vapor deposition by using hexamethyldisilylamine precursor

Silicon carbide (SiC) coating is deposited on C/C composite substrate for the first time by chemical vapor deposition (CVD) with hexamethyldisilylamine (HMDS, C6H19NSi2) as precursor and N2 as carrier gas in an intermediate deposition temperature range. The effects of deposition temperature on phase constitution, surface morphology and deposition rate of the coating are investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The coating exhibits a β-SiC (3C) phase at 1010 °C, 1060 °C and 1100 °C, coexistence of both α-SiC (2H) and β-SiC (3C) phases at 1130 °C and 1180 °C, as well as a single β-SiC (3C) phase again at 1220 °C. The morphology and microstructure of coating change significantly with deposition temperature. The change of phase constitution and surface morphologies are closely linked to nucleation, growth and defects formation in SiC crystals during CVD process.