Characteristics of plasma electrolytic oxide coating on magnesium-hydroxyapatite composites

Plasma electrolytic oxidation (PEO) is a surface modification of metals to grow a ceramic-like oxide coating with remarkably enhanced corrosion resistance. This work studies the characteristics of the PEO coating formed on magnesium-hydroxyapatite (Mg-HA) composites with HA concentrations of 0, 10, 20, and 30 wt% prepared by spark plasma sintering (SPS). Thin PEO coatings of 1–3 μm were successfully formed on all specimens in 0.5 M Na3PO4 electrolyte for 5 min. The plasma became finer, reducing the pore size and thickness, with increasing HA concentration. Agglomeration of HA particles in Mg-20HA and Mg-30HA inhibited coating coverage. EDS and XRD analyses confirmed the similar composition of Mg3(PO4)2 in all the coatings. The coating improved surface wettability and showed high apatite-forming ability in simulated body fluid. The optimum coating performance was obtained for Mg-10HA.