Synthesis of Hydroxyapatite Coatings on Titanium Substrates by Plasma Electrolytic Oxidation

In this study, hydroxyapatite (HA) coatings were synthesized on titanium substrates using the plasma electrolytic oxidation (PEO) technique to enhance corrosion resistance and improve the biocompatibility of implant materials. The experiments were conducted in an electrolyte containing calcium acetate hydrate and sodium dihydrogen phosphate monohydrate under a constant voltage of 500 V, with treatment durations of 1, 3, 5, and 7 minutes. The surface morphology and structural characteristics of the coatings were analyzed using various characterization techniques. X-ray diffraction (XRD) results revealed the distinct formation of hydroxyapatite phases when the treatment duration reached 7 minutes. Scanning electron microscopy (SEM) observations showed a uniformly porous surface morphology while energy-dispersive X-ray spectroscopy (EDS) confirmed the presence of calcium and phosphorus elements. Furthermore, corrosion performance evaluated in simulated body fluid (SBF) using Tafel polarization curves demonstrated that the PEO-coated samples exhibited significantly higher corrosion potentials and polarization resistance than bare titanium, indicating superior surface protection. In vitro cell culture experiments using BHK cells for 48 h and 72 h confirmed good cell attachment and proliferation on the HA-coated surfaces. These results demonstrate that hydroxyapatite coatings prepared by the plasma electrolytic oxidation method hold great potential for biomedical implant applications.