High-temperature active/passive oxidation and bubble formation of CVD SiC in O2 and CO2 atmospheres

The active oxidation, passive oxidation and bubble formation of CVD SiC were studied in O2 and CO2 at temperatures from 1650 to 2000 K. The active oxidation rates in O2 increased with increasing oxygen partial pressure (PO2); however, those in CO2 showed the maxima at specific PO2. The passive oxidation kinetics in O2 were either linear–parabolic or parabolic depending on temperature and PO2, whereas that in CO2 was always parabolic. The activation energies for the parabolic oxidation in O2 and CO2 were 210 and 150 kJ/mol, respectively, suggesting different rate-determining process in these atmospheres. The bubble formation was controlled by temperature and PO2 being independent of oxidant gas species. The linear and parabolic oxidation rates were accelerated by the bubble formation.