Comparative study of corrosions of aluminum alloys 2024 and 6101 at various pH values

Abstract

The corrosion behaviors of aluminum alloys 2024 and 6101 were studied in a medium with different pH values. The selected pH values were 2, 4, 6, 9, 11 and 13. Weight-loss tests were performed to assess the corrosion rate at these pH values, and analysis of electrochemical properties was conducted for the corrosion at pH = 4 and 11 in particular. The results showed that the corrosion rates of the aluminum alloys increased with the increase of the acidity or alkalinity of the corrosive medium. The corrosion resistance of aluminum alloy 6101 was better than that of aluminum alloy 2024 under neutral and acidic conditions; however, corrosion resistance of aluminum alloy 2024 was superior to that of aluminum alloy 6101 under alkaline conditions. The corrosion of aluminum alloy 6101 was very severe in a highly alkaline medium, and the corrosion rate reached an average value of 29.96 mm/year in an environment of pH = 13, with a large number of corrosion pits on the surface of the corroded sample.