Theoretical Investigation for the Active‐to‐Passive Transition in the Oxidation of Silicon Carbide

The oxidation of silicon carbide at high temperatures from 673.15 to 2173.15 K is investigated by using thermodynamic equilibrium calculations and a mass transfer model. The dominant reaction of the active‐to‐passive transition and five other dominant reactions, which are in six different temperature regions, have been determined according to the main equilibrium products. Then, a modified Wagner's model has been developed to determine the active‐to‐passive transition boundary by combining mass transport and thermodynamic calculations. The present theoretical calculations satisfactorily explained the reported experimental and theoretical data. The influence of flow rate on the active‐to‐passive transition boundary has been explained using our model. The rate controlling mechanism of the oxidation at the active‐to‐passive transition point is proposed.