Effects of the laser treatment and thermal oxidation behavior of CoNiCrAlY/ZrO2–8wt%Y2O3 thermal barrier coating

This paper is to investigate the effects of laser treatment for thermal barrier coating (TBC) layers. The two-layer TBC are composed of CoNiCrAlY bond coating by a vacuum plasma spray process and ZrO2–8wt%Y2O3 ceramic coating layer by an atmosphere plasma spray process. The Nd:YAG laser (wavelength 1.06μm, 60W) was used for laser treatment to coat surfaces. Different scanning speeds and powers were set to each sample and the surface structure was investigated by an acoustic emission monitoring system. The microstructure and surface morphology were analyzed by SEM and XRD. The thermally grown oxide (TGO) behavior was evaluated with a thermal oxidation test. In the case of the laser-treated TBC, the re-melted coating layer appeared newly on the surface of coating layers and a vertical crack was initiated from the surface. The thickness of TGO with laser treatment was smaller than that without laser treatment.