A curvature-dependent chemo-mechanical coupling model for two-dimensional oxidation on the curved surface

Abstract

Understanding the chemo-mechanical coupling effect during oxidation at elevated temperatures is of critical importance for revealing complicated oxidation mechanism and oxidation behavior, as well as proposing countermeasures for oxidation protection. There has been an intensive investigation of the chemo-mechanics in planar oxidation, while much less attention is paid to the issue of non-planar oxidation. In this work, we proposed a curvature-dependent chemo-mechanical coupling model to investigate the two-dimensional oxidation process on curved surfaces. The oxidation kinetics including the oxide thickness and oxide growth rate on the curved surfaces, as well as the stress distribution and evolution at the substrate-oxide interface, were demonstrated. Comparisons between the experimental observations and theoretical predictions validated the accuracy of the proposed model, and the phenomenon of inhibition of oxidation on both convex and concave surfaces was explained by the stress-curvature effect on the oxidation process. Furthermore, based on the proposed model, we proposed a parameter and established a phase diagram to characterize the interactions between the curvature effect and the oxide growth effect.