Effect of Immersion Time on Corrosion Resistance of Phytic Acid Coatings on AZ91D-Mg Alloy

Phytic acid coatings were formed on AZ91D-Mg alloy during immersion in 5.0 g/L phytic acid solution for different time. The corrosion resistance of the bare and coated samples was investigated using Tafel polarization and Electrochemical Impedance Spectroscopy (EIS) methods, and the corresponding electrochemical corrosion parameters were analyzed. The results show that the anodic and cathodic corrosion processes of AZ91D-Mg alloy are conspicuously inhibited with phytic acid coatings; the overall corrosion resistance index of AZ91D-Mg alloy is increased with immersion time; and the corrosion protection efficiency of phytic acid coatings is up to 97.8%.