Corrosion Behavior of Calcium-Phosphorus Coatings on AZ31B Mg Alloy by Plasma Electrolytic Oxidation in Hank's Balanced Salt Solution

In this study, plasma electrolytic oxidation (PEO) coating on AZ31B magnesium alloy, being in electrolyte of sodium phosphate with various calcium hydroxide concentrations was investigated. To do this, phosphate electrolytes having diverse calcium hydroxide concentrations of 1, 2 and 3 gram per liter were studied. The coated specimens microstructure studies and chemical composition were carried out using scanning electron microscopy (SEM) and X-ray diffraction pattern (XRD). In order to study the corrosion behavior of created coatings in various conditions, Potentiodynamic polarization experiments and electrochemical impedance spectroscopy (EIS) were measured in body simulated physiological solution. The results displayed that the highest corrosion resistance was achieved in the sample having 2 g/l calcium hydroxide with the lowest porosity and corrosion current density (2.23×10-6 A/cm2).