Improving the Corrosion Resistance of Electrodeposited HA Coating on Magnesium Alloy Using Phytic Acid Treatment

The hydroxyapatite composite coating was prepared on AZ31 magnesium alloy via electrochemical deposition method, and the effect of phytic acid treatment with different content on the adhesion of hydroxyapatite coating was investigated in this paper. The phase structure, microstructure, elemental composition and chemical bonds of hydroxyapatite composite coating were characterized by XRD, SEM, EDS, and FTIR, respectively. The bonding strength of the composite coating was investigated by tensile test. The corrosion resistance in Hank’s simulated body fluid was studied by immersion corrosion test, polarization curve test and EIS. The results showed that the phytic acid treatment could optimize the compactness and formed chemical bond with HA coating, which significantly improved the adhesion strength of the coating to improve the corrosion resistance of the AZ31 magnesium alloy. When the phytic acid concentration was 8 g/L, the adhesion strength was improved to 10.32 MPa and the corrosion rate was only 0.4647 mm/y.