Microstructure and microcrack evolution mechanism of thermal barrier coatings under CMAS infiltration and corrosion: Experimental and numerical modeling

The long lifetime of thermal barrier coatings (TBCs) is challenged by calcium-magnesium-aluminum-silicate (CMAS) infiltration and corrosion. In this paper, a coupled numerical model is integrated with CMAS corrosion experiments to elucidate the mechanism behind microstructure and microcrack evolutions in CMAS-corroded TBCs. The numerical results of the model accurately describe and explain the experimental phenomena, including CMAS penetration, corrosion and swelling of the ceramic top coating, corrosion-induced interface degradation, microcrack propagation, and their interactions. Results show that CMAS corrosion can lead to microcracks in TBCs, which become channels for further CMAS infiltration, accelerating the process and eventually leading to TBCs failure.