Synthesis, surface characterization and corrosion behaviour of anodic oxide film on aluminium

Anodic oxidation of aluminium was carried out in oxalic acid using cyclic voltammetry (CV). The anodizing parameters such as anodizing time, temperature, applied potential, concentration of oxalic acid and the studies of their dependence on the varied experimental factors were optimized to get better quality oxide coatings. The corrosion resistance of the oxide coatings formed at various conditions was studied by Tafel polarization and Electrochemical Impedance spectroscopy (EIS). In addition, significant changes in impedance were observed for the plates anodized under various conditions. In this study, the surface structure and phase composition of the anodized plates were also studied by scanning electron microscopy (SEM), atomic force microscopy (AFM), Energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). Comparison of SEM images of the anodized specimens prepared in various concentrations of oxalic acid showed that the plate anodized in 0.5 N oxalic acid concentration has uniform and compact surface.