Moisture-induced degradation of thermal barrier coatings on gas turbine blades in H2-enriched combustion environments

Growing demands to mitigate the environmental impact of gas turbines have intensified research into low-emission fuels, with hydrogen-enriched blends emerging as promising candidates due to their efficiency and reduced carbon footprint. However, the elevated water vapor generated during hydrogen combustion accelerates degradation of hot-section components, particularly thermal barrier coatings (TBCs). This work evaluates the moisture resistance of multilayer α-Al₂O₃/YSZ (Yttria-Stabilized Zirconia) TBCs under hydrogen-rich combustion conditions. A custom-designed combustor equipped with a distributed combustion system was developed to replicate representative environments, and a dedicated sample holder enabled controlled thermal and moisture exposure. Coatings comprising YSZ and α-Al₂O₃/YSZ architectures were subjected to flame exposure for 10 and 15 min. Post-exposure characterization using Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) revealed progressive microcracking and spallation in YSZ with increasing duration, whereas degradation in multilayer systems was largely confined to the α-Al₂O₃ surface. No significant phase transformations were observed in either configuration.