Thermo-mechanical Experiments of Y-PSZ Thermal Barrier Ceramic Coating with Bond Coat of Alumina

Abstract

In the present study, aluminum alloy (AlSi) substrates coated by Yttria stabilized zirconia used as thermal barrier have been investigated. The ceramic coating on the substrate is applied by plasma-spraying technique. Alumina (Al2O3) is used as a bond coat material. Four types of ceramic coating thickness (150, 250, 350 and 450 µm) were applied to AlSi materials which were cut out of diesel engine pistons with 100 µm thickness of bonding coat of Al2O3. The thermal torch and the thermal shock tests were conducted to coated samples which were made according to the international standards. Constant shock intensities were tested for 70 cycles on different thicknesses of the ceramic material and special attention was paid to the influence of thickness of the coating on the crazing phenomenon. Thermal resistance of thermal torch tested samples has been checked by drilling a hole in the middle of the samples and deformation time has been noted. Thermal shock tested samples were analyzed by X-ray diffraction machine and scanning electron microscopy machine. The diffractograms and micrographs have been obtained respectively for the samples. The diffractograms and micrographs of as sprayed samples and shock tested samples for different thickness have been compared, even the effect of thermal shock experiment on the different coating thickness of the ceramic have been analyzed. At the end of the tests, the most suitable ceramic coating thickness was determined.