Dynamic Behavior of CMAS Droplets on Laser-glazed Thermal Barrier Coatings (TBCs)

Calcium-magnesium-aluminosilicates (CMAS) are ingested by gas turbine engines and deposit on and infiltrate the thermal barrier coatings (TBCs) during high-temperature operation. When exposed to temperatures above 1200°C, the CMAS infiltrates the TBC, compromising its stress tolerance and leading to premature failure. Researchers have employed various surface treatment strategies to minimize the deposition of CMAS, one of which is laser glazing (i.e., remelting the top layer of the TBCs). However, the experiments were limited to static CMAS testing of the laser-glazed TBCs. In this study, the laser-glazing parameters were optimized to obtain a thin glazed layer at the surface of the TBCs. In an attempt to mimic real-world conditions, a commercially available CMAS powder was sprayed onto the laser-glazed 8YSZ coatings using an atmospheric plasma spraying process. Furthermore, the dynamic CMAS behavior was compared between the laser-glazed and as-sprayed TBCs. SEM/EDS and XRD analyses were performed to identify and quantify the elements and phases of the CMAS on the TBCs.