Abstract
The oxidation mechanism of SiC should be understood to use in combustion environments at high temperature. CVD SiC was oxidized in N2-O2 and Ar-O2 atmospheres in the temperature range between 1670 and 2010 K. Passive oxidation were observed below 1985 K. The oxidation kinetics changed from parabolic to linear-parabolic with increasing oxygen potential. In N2-O2, this transition occurred at higher oxygen potentials than in Ar-O2. Above 1985 K, bubbles formed independent of oxygen potentials at more than 1 kPa. In the oxygen potential range less than 1 kPa, the boundary oxygen potential between the bubble formation and passive oxidation increased with increasing temperature. In N2-O2, the boundary oxygen potential become about 1 order of magnitude lower than in Ar-O2. Oxide scales were well crystallized in Ar-O2, whereas amorphous SiO2 remained in N2-O2.
