The Preparation Of Graded Coating Of Ni-Al Intermetallic Compound On The Surface Of Copper

Nickel coating is electrodeposited on the surface of copper. The effects of current density and wetting agent on the deposition rates, the microstructure and the surface morphologiesof nickel coating were studied. The results show that the enhancement of current density and the wetting agent can accelerate the deposition rates and make the grains finer. When the current density was under 60A m2, the preferred orientation of nickel coating was (111) and when the current density was above 80A m2, the preferred orientation of nickel coating was (200).The effects of grain sizes, surface morphologies and texture of Ni deposits, the temperature of heat treatment and the treating time on the rate of Cu–Ni diffusion and the distribution of component and the microstructure of Cu–Ni diffusion layer were studied. The results show that the small grain sizes can promote Cu–Ni diffusion. The rough surface and (111) textures of Ni electrodeposits based on high current density can also promote Cu–Ni diffusion. The increase of temperature of heat treatment can increase the rate of Cu–Ni diffusion, too.The effects of grain sizes, surface morphologies and texture of Ni deposits, the temperature of heat treatment and the treating time on the rate of Ni-Al diffusion, the distribution of component and the microstructure of Ni-Al diffusion layer of Ni-Al diffusion layer and the forming of Ni-Al intermetallic compound phases were studied. The results show that the small grain sizes can promote Ni-Al diffusion. The rough surface and (111) textures of Ni electrodeposits based on high current density can also promote Ni-Al diffusion. The increase of temperature of heat treatment can increase the rate of Ni-Al diffusion. The Ni-Al coatings which contain several kinds of Ni-Al intermetallic compound and a gradient coating were formed with micro-hardness much higher than that of pure nickel coating.Based on the previous studies, the gradient coating of Cu-Cu solid solution with Ni-Ni-inetrmetallic compounds of Ni and Al was fabricated with proper technical parameters. The microstructure, wear resistance, high temperature oxidation resistance and corrosion resistance of the coating were studied. The results show that the corrosion resistance, wear resistance and high temperature oxidation resistance of Ni-Al coating were better than that of pure nickel coating.