Evolution of the microstructure and mechanisms of performance degradation in EB-PVD YSZ thermal barrier coatings corroded by volcanic ash at 1150°C

Volcanic ash (VA)/calcium-magnesium-alumina-silicate (CMAS) corrosion is a crucial issue causing the failure of thermal barrier coatings. This study focuses on the degradation process of electron-beam physical vapor deposition yttria-stabilized zirconia by natural VA at 1150 °C. The phase transformation and chemical reaction during VA attack were measured in real-time by in-situ high-temperature X-ray diffraction. The mechanical properties and the thermal conductivity of the as-deposited and VA corroded coatings were investigated. The correlation between these microstructural changes and the coatings’ properties are discussed. The degradation mechanisms are expected to guide the development of potential VA/CMAS mitigation methods.