Effect of preheating temperature of the substrate on residual stress of Mo/8YSZ functionally gradient thermal barrier coatings prepared by plasma spraying

Abstract

Based on the thermal elastic-plastic finite element theory and ANSYS finite element analysis software, a numerical model of Mo/8YSZ functionally gradient thermal barrier coatings prepared by the plasma spraying technology on the surface of aluminum alloy was established. The model considered the change of the thermophysical properties of the material with temperature and analyzed the influence of different preheating temperatures of the substrate on the value and distribution of the residual stress of the functionally gradient thermal barrier coating. The results showed that as the preheating temperature of the substrate increased, the distribution range of the radial residual tensile stress of the coating gradually decreased, and the distribution range of the radial residual compressive stress gradually increased. However, as the preheating temperature of the substrate increased, the distribution range of the axial residual tensile stress of the coating gradually increased and the distribution range of the axial residual compressive stress gradually decreased. With the increase of the preheating temperature of the substrate, the maximum value of the radial residual tensile stress, the maximum value of the radial residual compressive stress and the maximum value of the axial residual compressive stress of the component increased, but the maximum value of the axial residual tensile stress of the component showed a tendency of decreasing first and then increasing. Compared with the axial residual tensile stress of the component, the change of the preheating temperature of the substrate had a greater impact on the axial residual compressive stress, the radial residual compressive stress and the radial residual tensile stress of the component. Compared with other locations of the interface between the substrate and the coating, there was a larger abrupt change in the residual stress at a position about 0.5 mm from the edge of the interface. Considering the distribution of residual stress and sudden changes in stress, the preheating temperature of the substrate should be controlled at 150 °C.