Sealing of anodized aluminum with phytic acid solution

Sealing effect of phytic acid (PA) on the sulfuric acid anodized aluminum was studied by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), scanning Kelvin probe (SKP), SEM and EDS. Unsealed anodized aluminum displayed a porous structure and had poor corrosion resistance. The pores were not only filled, but also a PA conversion film with 3–4μm was formed when anodized aluminum was immersed in 2.5 wt.% PA solution with pH of 1.5 for 15min at 90°C. Anodized aluminum with PA sealing exhibited better corrosion resistance, compared to the anodized aluminums sealed by boiling water and dilute CrO3 solution. [Display omitted] •Sealing of anodized aluminum by immersing in phytic acid (PA) solution•PA sealing both filled the pores of anodized aluminum and formed a PA conversion film.•Synergism of filling effect and PA film greatly improved corrosion resistance of anodized aluminum.•Anodized aluminum with PA sealing outperformed other sealing methods.