Study on the Secondary Cathodic Deposition Modification and Properties of Anodic Oxidation Coating on 6061 Aluminum Alloy

This paper proposes a method for preparing a ceramic-metal composite coating by using different concentrations of H₃PO₄ as an etching solution to etch the hard anodized aluminum oxide coating and modify it by cathode deposition of Ni. This method successfully solves the problem of low hardness and poor wear resistance of the hard anodized aluminum coating. The bonding effect between the hard anodized aluminum coating and the Ni layer after etching with different concentrations of H₃PO₄ was systematically studied, and friction, corrosion and coating bonding tests were carried out. The results show that the Ni ions in the AA4% sample completely penetrated into the hard anodized aluminum coating, and a good interface fusion was achieved between the oxide layer and the Ni layer. The main components of the coating are Al₂O₃ and Ni. The AA4% sample exhibited excellent wear resistance and strong coating bonding. Under a load of 5 N, the wear width of the AA4% sample is reduced by 52.49% compared with that of the AA sample, and the wear depth is almost invisible. At the same time, the deposition of Ni reduced the chemical stability of the coating, resulting in a decrease in the corrosion resistance of the composite coating. The corrosion rate of the AA4% sample increased by 1.7522 × 10⁷% compared with the AA sample. In summary, the wear resistance of the hard anodized aluminum coating has been significantly improved after secondary Ni deposition treatment, which provides important guiding significance for the application of ceramic-metal composite coatings in the field of friction.