Microstructural evolution and corrosion mechanism of thermal/environmental barrier coatings against molten calcium–magnesium–alumino–silicate

Ceramic matrix composites (CMCs) used in gas turbine engines are required to resist corrosion caused by calcium‑magnesium-alumino-silicate (CMAS) at higher temperature. In this study, the corrosion behavior and microstructural evolution of (Gd0.9Yb0.1)2Zr2O7/Yb2SiO5/Yb2Si2O7/Si-70 wt% HfO2 (GYbZO/YbMS/YbDS/70SH) thermal/environmental barrier coatings (T/EBCs) prepared via plasma spray-physical vapor deposition (PS-PVD) were investigated after exposure to CMAS at different temperatures (1300, 1400, and 1500 °C) for 5 h and 25 h. The results showed that the corrosion morphology of the T/EBCs was significantly affected by the exposure temperature and time. The dense layers blocked the capillary penetration of CMAS. T/EBCs with feather-like columnar structures and dense layers provided stress tolerance; however, transverse cracks accelerated the CMAS corrosion. This study provides new insights into resistance of T/EBCs to CMAS corrosion.