Corrosion of CVD Silicon Carbide in 500°C Supercritical Water

A high-purity CVD β-SiC showed a relatively low corrosion rate in deoxygenated supercritical water at 500°C. The corrosion rate was lower than that previously reported for CVD SiC in 360°C water and much lower than that reported for sintered and reaction-bonded SiC. The present study confirmed that CVD SiC was preferentially attacked at the grain boundaries. Analytical examinations did not reveal the presence of a measurable oxide scale. As a result, it is believed that corrosion of the high-purity SiC occurred via hydrolysis to hydrated silica species at the surface that were rapidly dissolved into the supercritical water.