Feature of interfacial bonding achieved by medium-velocity particle impacts in cold spray

Due to the low deposition temperature and high materials building rate, cold spraying can be used as additive manufacture technology. The inter-particle bonding in cold-sprayed coating is considered to be the most crucial factor determining its mechanical properties, physical and chemical behavior such as tensile strength, hardness, electrical and thermal conductivities, as well as corrosion resistance. Therefore, in this study Cu coatings are prepared by cold spraying and the feature of interfacial-particle bonding is investigated. Results show that an extremely dense Cu coating with very little pores is prepared. Quantitative analysis with the image analysis indicates that the porosity of coating is only 0.12%. The coating micro-hardness is about 163 HV01 which is much higher than that of pure Cu bulk. The electrical conductivity of as-sprayed reaches 76 %IACS which is close to that of cold rolled pure Cu bulk. Tensile tests show that the mean ultimate tensile strength of cold sprayed Cu sample is about 65.5 ± 5.5 MPa. The elongations to failure of all the Cu samples do not exceed 0.2%. Moreover, the mean Young modulus obtained from tensile curves is merely 0.65 ± 0.5 GPa.