Characterization of microstructures of thermal oxide scales on silicon carbide using transmission electron microscopy

Abstract

Hexagonal single crystal silicon carbide was thermally oxidized in pure oxygen and in air at 1473 K. The thermally formed oxide scales were composed mostly of amorphous silica. However, some crystalline phase oxide scales were observed randomly distributed on the formed oxide scale. The ratio of crystalline scale to overall oxide scale was less than 5 percent. We characterized the microstructures of the thermally formed oxide scales using transmission electron microscopy with low-dose observation technique. The oxide scales in some regions were divided into two layers, with crystalline scale on the upper and amorphous scale on the lower layer. Traces of calcium were found in the crystalline phase oxide scale, which could have influenced the crystallization.