Effect of the substrate surface and coating powder hardness on the formation of a cold sprayed composite layer

In this study, the powder hardness and substrate surface hardness on the coating formation in the cold spray process was investigated. The AA6082 aluminum alloy hardened by the shot-peening process was used as the base material. Two different metallic powders and a ceramic particle powder were used as powder materials with different hardness. Thus, the powder particles from different materials were sprayed onto the surface under the same spraying process conditions. In order to obtain a workpiece surface with different hardness values, shot-peening treatment was applied to the substrate material at different treatment times. According to the microstructural examination, the harder metallic coating powder has accumulated more and the lower hardness metallic coating powder has accumulated less when the substrate material hardness increases. Al2O3 particles in the layer formed were distributed close to homogeneous. Furthermore, the size of Al2O3 particles near the contact surface has become much finer especially in the long-term shot peened samples due to their higher hardness. From the indentation experiments, the elastic behavior and recovery amount of the composite coating layer increased due to the increase of the substrate surface hardness, and the stress distributions were performed less after the load was removed.