Microstructure characterization of thermal barrier coatings glazed by a high powder laser

Abstract. Thermal barrier coatings have been widely used in in both energy and propulsion systems. Plasma-sprayed thermal barrier coatings have relatively high interconnected porosity and lamina structure, which bring out low bond strength, and lead to a short thermal cycling life. Lasers can be used for modification of materials surface. In this paper, plasma-sprayed thermal barrier coatings were laser-glazed by a high power laser in order to modify the structures. The microstructure of laser-glazed TBCs is investigated. The change on surface roughness has been examined. The result indicates that a smooth and dense glazed surface with craters and a network of microcracks is obtained after laser-glazing. The laser-glazed region consists of a columnar microstructure. There are segmentation microcracks in the laser-glazed coatings, which don’t run through the coatings along thickness. Surface roughness has been reduced significantly for the laser treated ceramic coatings