Preparation and corrosion resistance of magnesium phytic acid/hydroxyapatite composite coating on Mg alloy by microwave assisted method

A magnesium phytic acid/hydroxyapatite composite coating was rapidly prepared on AZ31 Mg alloy substrate by microwave assisted method. The surface morphology and composition, as well as the corrosion resistance, were characterized by FESEM, EDS, XRD and electrochemical tests. The influence of pH value of phytic acid solution on the microstructure and corrosion resistance of the magnesium phytic acid/hydroxyapatite coatings was investigated. The biodegradation and biomineralization behavior of Mg alloy and its coatings in simulated body fluid (SBF) were evaluated via immersion tests. The results show that when the pH value of phytic acid solution is 5.0, the magnesium phytic acid/hydroxyapatite composite coating is uniform and crack-free, with a good interface bonding to the substrate. The electrochemical measurements in SBF reveal that magnesium phytic acid/hydroxyapatite coating with pH=5.0 exhibits the best corrosion resistance compared with those with other pH values. The magnesium phytic acid/hydroxyapatite composite coating can induce apatite deposition and effectively improve the corrosion resistance of Mg alloy in SBF.