Proposition of a robot-based free diamond abrasive grinding process and its influence on the characteristics of plasma-sprayed 8YSZ coatings

Thermal-sprayed coatings are expected to have a relatively smooth surface when used under certain service conditions, such as to improve their erosion resistance or decrease the adhesion of CMAS sands. In this study, a new method for grinding ceramic coatings was proposed that uses an industrial robot, a floating spindle, a rubber binder grinding head, and diamond plaster to automatically grind ceramic coatings on basis of free abrasive grinding. Typical 8YSZ thermal barrier coatings (TBCs) were created on nickel-based superalloy plates using atmospheric plasma spraying (APS) in order to explore the impact of such grinding on their morphology and comprehensive performance. Following the grinding with the proposed process, the coating's surface roughness, removal weight and thickness, as well as 3D surface morphology were all measured. The microstructure, wetting angle, infrared emittance, microhardness, bonding strength, particulate erosion resistance, and thermal cycling life of the as-sprayed and ground 8YSZ coatings were comparatively studied using the corresponding characterization instrument. The results show that the coating's surface roughness can be decreased to roughly 1 μm, and its removal thickness ranges between 45 and 90 μm. Besides from the wettability of the droplet on the coating's surface rises, the coating's infrared emittance, mechanical properties, thermal cycling life, and erosion resistance are not noticeably different after grinding, demonstrating that such novel grinding technique won't weaken the microstructure or shorten the coating life. It could offer guidance for the urgently required development of grinding processes for ceramic coatings with complex surfaces.