Oxidation behavior of 5A06 and 2A12 aluminum alloys in sulfuric-adipic acid and electrochemical property of anodic oxide film

Abstract

Anodic films of 5A06 and 2A12 aluminum alloys were obtained in sulfuric-adipic acid. The influence of alloy phase on anodic oxidation behavior,and the structure and corrosion resistance of the oxide film were analyzed. Electrochemical results were completed by the polarization curve and electrochemical impedance spectroscopy( EIS),and microstructure characterization of the anodic film was carried out by field emission-scanning electronmicroscopy( FE-SEM). 2A12 aluminum alloy showed two current peaks during anodization process,which shown that the dissolution of copper phase would influence the process of anodic oxidation.The pores of 2A12 anodic oxide film are not neat and have serious connectivity. Enrichment of copper phase promotes the production of oxygen. With the same soaked time,the corrosion potential of anodic oxide film on5A06 is higher and corrosion current is lower than those of 2A12. The corrosion resistance of anodic oxide film on 5A06 is better. There properties all attributed to the higher porosity of Al-Cu alloy than that of Al-Mg alloy.