Crack healing in silicon carbide

Crack healing in silicon carbide was investigated by introducing cracks into specimens and subsequently heat-treating the specimens. It was observed that cracks were healed, dramatically increasing the strength, by being filled with amorphous silica produced by the oxidation of silicon carbide. It was shown that the residual stress produced by the thermal expansion mismatch between silica within cracks and surrounding silicon carbide played a major role in the increase of the strength. Our results imply that a simple oxidation heat treatment can improve the reliability of silicon carbide components.