High‐Temperature Active Oxidation of Chemically Vapor‐Deposited Silicon Carbide in CO─CO 2 Atmosphere

Active oxidation behavior of CVD‐SiC in CO─CO 2 atmospheres was investigated using a thermogravimetric technique in the temperature range between 1823 and 1923 K. The gas pressure ratio, P CO2 / P CO , was controlled between 10 −4 and 10 −1 at 0.1 MPa. Active oxidation rates (mass loss rates) showed maxima at a certain value of P CO2 / P CO , ( P CO2 / P CO ) * , In a P CO2 / P CO region lower than the ( P CO2 / P CO ) * a carbon layer was formed on the SiC surface. In a P CO2 / P CO region higher than the ( P CO2 / P CO ) * , silica particles or a porous silica layer was observed on the SiC surface.