Corrosion mechanisms of high-entropy rare earth zirconate (Gd0.2Y0.2Er0.2Tm0.2Yb0.2)2Zr2O7 exposed to CMAS and multi-medium (NaVO3+CMAS)

The wettability and thermal corrosion behavior of CMAS and CN (CMAS+NaVO3) on high-entropy rare-earth zirconate (Gd0.2Y0.2Er0.2Tm0.2Yb0.2)2Zr2O7 (HEZ) at high temperature were studied and compared. The results reveal that HEZ is a promising TBCs material with good anti-CMAS performance. However, HEZ exhibits poor resistance to CN, and the reaction layer fails to effectively alleviate the melt penetration. Based on the calculation of OB (optical basicity) theory, the possibility that NaVO3 can improve the reaction activity of CMAS is ruled out. It was determined that NaVO3 depolymerizes the internal network structure of the CMAS, resulting in a lower melting point and viscosity, stronger wettability, and permeability of CN compared to CMAS, thus posing greater harmfulness. The influence of rare earth elements with different ionic radii on the formation of multicomponent RE-crystal was researched by crystal structure analysis and first-principles calculation, providing a theoretical basis for the reliability of the corrosion mechanism.