Molten CMAS resistance of PS-PVD (Gd_0.2Y_0.8)₃Al₅O₁₂ /YSZ thermal barrier coating with high adherence

Calcium-magnesium-alumina-silicate (CMAS) deposits significantly accelerate the degradation of thermal barrier coatings (TBCs) in advanced aeroengines, thereby posing a substantial threat to aviation safety. In this study, (Gd_0.2Y_0.8)₃Al₅O₁₂ (GYAG)/YSZ double-ceramic-layer thermal barrier coatings (TBCs), comprising dense GYAG on top and columnar YSZ beneath, were fabricated via plasma spray-physical vapor deposition (PS-PVD) in a single-step process to mitigate CMAS attack. High-temperature exposure tests at 1250 °C demonstrated the excellent phase stability of GYAG coating and interface stability of GYAG/YSZ coating. The interactions between CMAS and GYAG/YSZ coatings were investigated. Results showed that CMAS melt infiltration was suppressed. GYAG coating reacted rapidly with CMAS to crystallize apatite, garnet and anorthite phases with high-melting-point. These crystalline phases are alternatively distributed and collectively inhibit CMAS infiltration. The doping of Gd in GYAG coating facilitated precipitation of apatite, which is crucial for CMAS resistance enhancement.