Investigation of CMAS corrosion resistance for gradient Y2O3 stabilized ZrO2.

The threat of calcium‑magnesium-alumina-silicate (CMAS) melt corrosion in thermal barrier coatings (TBCs) is significant at elevated working temperatures. In this study, a gradient Y 2 O 3 stabilized ZrO 2 coating (gradient YSZ coating) was designed and prepared by electron beam physical vapor deposition (EB-PVD) and its CMAS corrosion resistance was examined. The CMAS corrosion resistance test on the YSZ pellets highlighted the significance of dissolved Y 2 O 3 and identified the critical Y 2 O 3 content. Compared with the classical 8 wt% Y 2 O 3 stabilized ZrO 2 (8YSZ) coating, new crystal phases generated in the gradient YSZ coatings effectively blocked the CMAS melt infiltration for a short time; further, even after a long time, the CMAS melt was primarily distributed in the upper part of the gradient YSZ coating. In addition, the impact of coating microstructure on the CMAS resistance was investigated. The results showed the dense-gradient YSZ coating outperformed the 8YSZ coating on the resistance to CMAS infiltration. Finally, it is demonstrated that the gradient YSZ coating has potential applications against CMAS attacks, providing valuable design guidelines for TBCs with balanced corrosion resistance and promising mechanical properties. • A gradient Y 2 O 3 stabilized ZrO 2 (YSZ) coating was deposited by EB-PVD and exposed to CMAS corrosion. • New phases, which blocked CMAS melt permeation for a short time, generated in the gradient YSZ coating. • Over a prolonged period, the gradient YSZ coating remained intact and exhibited better CMAS corrosion resistance. • The gradient composition modification also enhanced the CMAS resistance of dense coatings. [ABSTRACT FROM AUTHOR]