HIGH-TEMPERATURE OXIDATION OF CHEMICALLY VAPOR-DEPOSITED SILICON-CARBIDE IN WET OXYGEN AT 1823 TO 1923-K

The oxidation of chemically vapor-deposited SiC in wet O2 (water vapor partial pressure = 0.01 MPa, total pressure = 0.1 MPa) was examined using a thermogravimetric technique in the temperature range of 1823 to 1923 K. The oxidation kinetics follow a linear-parabolic relationship over the entire temperature range. The activation energies of linear and parabolic rate constants were 428 and 397 kJ.mol-1, respectively. The results suggested that the rate-controlling step is a chemical reaction at an SiC/SiO2 interface in the linear oxidation regime, and the rate-controlling step is an oxygen diffusion process through the oxide film (cristobalite) in the parabolic oxidation regime.