High‐Temperature Passive Oxidation of Chemically Vapor Deposited Silicon Carbide

The oxidation behavior of chemically vapor deposited (CVD) SiC at high temperature was investigated using a thermogravimetric technique in the temperatures range of 1823 to 1948 K. The specimens were prepared by chemical vapor deposition using SiCl 4 , C 3 H 8 , and H 2 as source gases. The oxidation behavior of the CVD‐SiC indicated “passive” oxidation and a two‐step parabolic oxidation kinetics over the entire temperature range. The crystallization of the SiO 2 film formed may have caused this two‐step parabolic behavior. The parabolic oxidation rate constant ( K p ) varied with the square root of the oxygen partial pressure ( P 1/2 O 2 ). The activation energy for the oxidation was determined to be 345 and 387 kJ · mol −1 . These values suggest that the diffusion process of the oxygen ion which passes through the SiO 2 film is rate‐controlling.