Electrochemical Corrosion Behavior and Anodic Oxidation Process of 9S75 Aluminum Alloy

The electrochemical corrosion behavior of 9S75 aluminum alloy in 3.5% NaCl solution with different pH was tested using polarization curves. An anodizing process of sulfuric acid was introduced and the optimum conditions of constant voltage anodization of sulfuric acid were determined by orthogonal test. The results showed that the corrosion rate of aluminum alloy decreased with the increase of pH in acidic solution. In alkaline solution, the corrosion rate of aluminum alloy increased with the increase of pH. The optimum anodic oxidation voltage of 9S75 aluminum alloy was 20 V, the oxidation time was 35 min, and the mass concentration of sulfuric acid was 184 g/L. The oxide film obtained by this method was amorphous alumina, which had a honeycomb structure and a film thickness of about 16 μm. The oxide film plays an important role in protecting the surface of the aluminum alloy.