Dynamic CMAS–TBC Interactions: Infiltration and Degradation in APS YSZ and SPS HEZ Coatings

 

 

During operation, gas turbine engines can ingest siliceous particulate matter, which subsequently forms calcium–magnesium–alumino–silicate (CMAS) deposits on the hot surfaces of thermal barrier coatings (TBCs). When temperatures exceed 1200 °C, CMAS may penetrate the coating, leading to reduced strain tolerance and early failure. Previous studies have reported that dynamically deposited CMAS does not significantly infiltrate TBCs due to insufficient high-temperature exposure time. In this study, commercially available CMAS powder (AFRL-03) was deposited onto two types of TBCs i.e., conventional 8YSZ and high-entropy zirconate Y₀.₂Nd₀.₂Sm₀.₂Gd₀.₂Dy₀.₂)₂Zr₂O₇ (HEZ) coatings, using an atmospheric plasma spraying (APS), and suspension plasma spraying (SPS) process, respectively. The substrate temperature was maintained above 1200 °C with a dwell time of 20 minutes to better simulate severe operating conditions. The infiltration behavior of CMAS in both coatings was systematically investigated using SEM/EDS analyses. Furthermore, the key phases responsible for CMAS-induced degradation and coating failure were identified.

 

Keywords: Atmospheric Plasma Spray (APS), YSZ, HEZ, CMAS, AFRL-03.