Development and characterization of MgO/hydroxyapatite composite coating on AZ31 magnesium alloy by plasma electrolytic oxidation coupled with electrophoretic deposition

Magnesium alloys have been gaining much importance as metallic biodegradable materials for clinical applications. The present study explores the possibility of developing MgO/hydroxyapatite (HA) composite coating on AZ31 magnesium alloy in order to control its biodegradability. The coating was developed by using a hybrid process combining plasma electrolytic oxidation (PEO) and electrophoretic deposition (EPD) and characterized to substantiate the presence of hydroxyapatite incorporated in the oxide phase. Biodegradability of HA coating was evaluated by conducting potentiodynamic polarization tests at a pH of 4.5, simulating the condition of osteoclast resorption in-vitro and also in simulated body fluid (SBF) environment at a pH of 7.4. The results showed that the MgO/HA composite coating significantly improved the corrosion resistance of AZ31 magnesium alloy in both the conditions.