Characterization of stress in a thermal barrier coating during CMAS corrosion using Ce³⁺ photoluminescence spectroscopy

Abstract

The stress caused by calcium–magnesium–alumino–silicate (CMAS) corrosion is a critical factor in thermal barrier failure of thermal barrier coatings (TBCs). For the service safety of TBCs, it is important to characterize the stress inside TBCs during CMAS corrosion using a nondestructive and accurate method. In this study, photoluminescence spectroscopy technology was applied to characterize the stress in TBCs during CMAS corrosion. First, TBC specimens containing yttrium–aluminum–garnet doped with trace Ce3+ ions (YAG:Ce3+)/yttrium oxide partially stabilized zirconia double‐ceramic‐layer were prepared by atmospheric plasma spraying. Then, CMAS corrosion experiments were performed using the TBC specimens, and a mechanical model was derived based on Ce3+ photoluminescence spectroscopy to investigate the stress in the TBCs. Finally, the microstructure, extent of CMAS corrosion and stress field in TBC specimens, was characterized. The results reveal that the penetration of CMAS leads to local stress concentration and a nonlinear stress distribution from the outside surface to the inside of the YAG:Ce3+ layer. In addition, an increase in corrosion time, temperature, and CMAS concentration can significantly influence the evolution of the stress field in TBCs.