Oxidation mechanism and multi-physics coupling modeling of thermal barrier coated Ni-based single crystal superalloys

A combined experimental and theoretical framework was employed to investigate the high-temperature oxidation behavior of Ni-based single crystal superalloys, both with and without coatings. The results indicate that the thermal barrier coating (TBC) serves as an effective barrier, significantly retarding aluminum depletion within the substrate and preserving its mechanical integrity against oxidative degradation. Furthermore, oxidation kinetics were evaluated by analyzing the thickening rates of the γ' free layer and the thermally grown oxide (TGO) layer, which serve as direct indicators of the oxidation rate. Integrating oxidation mechanisms with multi-physics coupling, thermo-mechanical model and chemo-mechanical diffusion model were developed to simulate TBC oxidation behaviors. These models successfully captured the spatiotemporal evolution of TGO morphology, oxygen concentration, and stress fields, thereby clarifying the failure mechanisms. Finally, coating failure was assessed using a criterion based on oxide scale spallation.