Microstructure evolution and thermochemical interaction of dysprosia stabilized zirconia with CMAS attack

Thermal/Environmental barrier coatings (T/EBCs) operating in environments laden with siliceous debris are increasingly vulnerable to degradation from molten calcium‑magnesium-alumina-silicate (CMAS) deposits. As a promising ceramic coating material, the microstructure evolution and thermochemical interaction of dysprosia stabilized zirconia (DySZ) with CMAS attack at 1250 °C were systematically investigated. The results indicate that CMAS preferentially corrodes the DySZ from their grain boundary. The inherent grain boundary segregation characteristics of solute Dy atoms provided a convenient channel for grain boundary corrosion. The thermochemical reaction between DySZ and CMAS leads to DySZ destabilization, which carried out through in-situ phase transformation and dissolution-recrystallization processes. It is proposed that improving DySZ corrosion resistance can be achieved by introducing pentavalent stabilizers to reduce Dy segregation or promoting the crystallization precipitation kinetics of CMAS. These findings may contribute to laying the foundation for the material design of ceramic surface layers in long-life T/EBCs systems.