Oxidation behavior of silicon carbide at 1200 °C in both air and water–vapor-rich environments

• SiC exhibits passive or active oxidation, depending on oxidation environment.
• Oxidation conditions do not influence microstructure of the oxide formed on SiC.
• The oxides showed a different chemistry depending on oxidation environment.
• Dominant oxide formed on SiC in the earliest stages was amorphous Si2O3.

Oxidation of SiC in both air and water–vapor–rich environments was carried out at 1200 °C to examine the effects of different oxidation conditions on the early-stage oxidation behavior of SiC. Two different types of SiC oxidation behavior were found, passive or active, depending on the oxidation environment. All the samples possessed amorphous oxide layers, regardless of the oxidation environment. Three Si oxidation states (SiO, Si2O3, and SiO2) were observed in this layer. The amorphous Si2O3 state was dominant, and the ratio of the three different states changed with the test conditions.