The effect of temperature and roughness of the substrate surface on the microstructure and adhesion strength of EB PVD ZrO2-%8wtY2O3 coating

Thermal barrier coatings are of great interest in increasing the working temperature and thus, improving the efficiency of turbine engines. In this study, coating was conducted on nickel-base superalloy substrates using physical vapor deposition process and the electron beam evaporation technique of Yttria-stabilized Zirconia discs. In order to characterize the coatings including microstructure, topography and phase structure, field emission scanning electron microscopy, atomic force microscopy and X-ray diffraction analysis were used, respectively. The scratch test was also used to evaluate the adhesion strength of the coating. It was observed that at the temperature of 470 degrees C, the coating has no preferential orientation. By increasing the substrate temperature to 750 degrees C, the intensity of the peak (211) was reduced, while that of the peak (101) was sharply increased, such that at the substrate temperature of 750 degrees C, the coating had only the preferred orientation (101). Increasing the substrate temperature from 470 degrees C to 750 degrees C enhanced the critical force (Lc) from 8.2 N to 25.1 N. Increasing the substrate roughness from 0.55 mu m to 3.43 mu m enhanced the coating roughness from 0.62 mu m to 3.71 mu m raised the columnar diameter from 36.98 nm to 120.9 nm and reduced the critical force (Lc) from 18 N to 6.3 N.