Dynamic behavior of CMAS Droplets on 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, experiments have been limited to static CMAS testing of the laser-glazed TBCs. In an attempt to mimic real-world conditions, a commercially available CMAS powder was sprayed onto the 8YSZ and laser-glazed 8YSZ coatings using an atmospheric plasma spraying process. In this study, the effect of different spray angles (30°, 60° and 90°) of CMAS on the different surfaces was investigated. In addition, the dynamic CMAS behavior was compared between the as-sprayed, polished, and laser-glazed TBCs. SEM/EDS and XRD analyses were performed to identify and quantify the elements and phases of the CMAS on the TBCs.

Keywords: Dynamic CMAS, spray angles, laser glazing, Atmospheric plasma spray, YSZ.