Effect of coating time on the corrosion behavior of ceramic coatings containing hydroxyapatite nanoparticles by plasma electrolytic oxidation method on AZ31 Mg alloy in simulated body fluid

In this study, the effect of coating time on the microstructure and corrosion behavior of AZ31 Mg alloy coated by plasma electrolytic oxidation (PEO) method has been investigated. For this purpose, phosphate-based electrolyte containing hydroxyapatite nanoparticles was used at different times of 5, 10 and 15 minutes. The surface properties and chemical composition of the coatings were investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD) pattern. The corrosion properties of coatings in the simulated body fluid have been studied by potentiodynamic polarization and electrochemical impedance spectroscopy tests. The results of this study showed that with increasing the coating time to 15 minutes, the size of the pores and the thickness of the coatings increased. The coating created in 10 minutes has the lowest percentage of porosity among the samples. The results also showed that the coating created in 10 minutes had the lowest corrosion current density (2.33 × 10-8 A/cm2) among the samples.