Controlling the Chemical Composition of the Interface Thermally Grown Oxides to Prolong the Lifespan of Thermal Barrier Coatings Based on Interfering Aluminum Diffusion Mechanism

Abstract

This study places great emphasis on the relationship between the TGO chemical composition and the TGO growth rate and the mechanical property of thermal barrier coatings upon isothermal oxidation. The results indicate that the control of the θ-Al2O3α-Al2O3 phase transformation can have significant effects on the subsequent isothermal oxidation during the earlier stage of isothermal oxidation. The formation of (Al, Cr)2O3 oxide sub-layer originated from the textured and larger grain of α-Al2O3 can influence the potential TBCs lifetime. Additionally, the potential longer oxidation lifetime of TBCs that subjected to the appropriate vacuum heat pre-treatment can be attributed to the larger absorptive energy of the TGO area prior to its fully microcrack imperfection propagation. Most importantly, TBCs delamination was determined by the steady-state energy release rate in ceramic topcoat and TGO, the TGO and the interface, as well as the formation and development of the microstructure and composition of imperfections in the vicinity of the interface.