Abstract
In the present study, Cu coating was deposited by cold spraying and the electrical resistivity of the coating in both directions parallel and perpendicular to the coating surface was measured to investigate the anisotropy of the coating. Annealing treatment was applied to the coating to examine its effect on the microstructure and properties of cold-sprayed Cu coating. The examination of coating microstructure evidently revealed that the coating was constituted by flattened particles and the interfaces were clearly observed between the deposited particles. The anisotropy in microstructure and electrical resistivity was present in cold-sprayed Cu coating. The electrical resistivity of the as-sprayed coating was higher than that of Cu bulk. Moreover, the electrical resistivity along the direction parallel to the coating surface was lower than that along the perpendicular direction. On the other hand, it was found that the annealing led to the enhancement of particle interface bonding and evident recrystallization of the elongated grains and remarkable grain growth as well. The annealed coating presented an equiaxed grain structures similar to annealed Cu bulk with particle interfaces almost disappeared under certain annealing condition. The coalescence of voids or oxides in the coating was clearly observed at high annealing temperature. Moreover, the annealed coating yielded an electrical resistivity and microhardness comparable to Cu bulk.
