Growth kinetics and the irreversible deformation of thermally growth oxide (TGO) critically affect the delamination and cracking at the interface of thermal barrier coatings (TBCs). In this study, TGO dynamic growth during furnace cycles is simulated using three different approaches. The stress evolution and damage characteristics near the interface are compared in various TGO growth modes. Furthermore, the influences of TGO creep at high temperatures on the interface delamination and coating failure are also investigated. The results reveal that TGO growth achieved through material transformation (growth mode III) leads to earlier interface delamination compared to element swelling methods (growth mode I and II). Although the stress value in growth mode II is higher than that in growth mode I after all cycles, earlier delamination and spallation occur in mode I due to faster stress accumulation in the initial stage of thermal cycle. Moreover, rapid TGO creep is found to reduce the accumulated stress within the ceramic layer and delay the onset of interface delamination. These findings provide important theoretical insights for the development and life assessment of advanced TBCs.

The intrinsic defects in thermal barrier coating (TBC) seriously affect its thermal insulation performance and service life. In this work, four typical TBC models are developed based on the same image to quantitatively compare the effects of defects on insulation and interface damage. The coupling behavior of thermally grown oxide (TGO) and gradient thermal cycling is considered. The propagation and evolution of intrinsic, pore edge, and interface cracks in the multi-defect model are explored. Results indicate that intrinsic cracks cause a temperature difference of up to 15 °C on the flat coating surfaces. Intrinsic defects have no effect on interface temperature. Compared to the defect-free model, intrinsic cracks result in a maximum increase of 70% in normal stress near the interface and a 48% increase in shear stress. The fully damaged area in the POR-CR model is 40% higher than that in the HOM model. Based on the POR-CR model, which is closer to the real microstructure, the merging methods of internal and interface cracks are summarized into six types. The relevant results can provide important data support for a comprehensive understanding of the failure mechanism of in-service coatings and accurate prediction of service life.