Effect of Surface Modification on Erosion Behavior of Alumina-Samarium Strontium Aluminate Composite Thermal Barrier Coatings

Abstract

The mechanical and tribological characteristics of a thermal barrier coating are highly critical in gas turbine applications to resist high-temperature oxidation, corrosion, and solid particle erosion. In the present investigation, a composite coating with alumina and samarium strontium aluminate has been developed through a plasma spraying process. The as-coated composite top coat consisted of three phases ?-alumina, ?-alumina, and Sm<inf>2</inf>SrAl<inf>2</inf>O<inf>7</inf>. The as-coated surface is re-engineered with an Nd: YAG fiber laser to improve the mechanical and microstructural properties. The laser-treated samples showed a better erosion resistance than the as-coated samples. Despite the surface treatment, both the as-coated and the laser-treated samples showed a higher ‘average erosion value’ at an impact angle of 90° for the test temperatures of 200 and 800 °C. In addition, the as-coated and the laser-treated samples have a higher erosion rate at 800 than at 200 °C for the selected impact angles, with a mixed mode of material removal presenting both ductile and brittle failure mechanisms. © ASM International 2024.