Deposition of hydroxyapatite-incorporated TiO2 coating on titanium using plasma electrolytic oxidation coupled with electrophoretic deposition

A porous hydroxyapatite (HA)-incorporated TiO2 coating has been deposited on the titanium substrate using a plasma electrolytic oxidation coupled with electrophoretic deposition (PEO-EPD). Potassium titanium(IV) oxalate is decomposed by micro arcs generated on the anode producing TiO2 while HA particles have been simultaneously deposited on anode during EPD process. Hydroxyapatite and TiO2 particles have been coagulated into roundish conglomerates with the average diameter in a range of 200-600 nm. The microstructure, as well as elemental and phase composition of the coatings have been examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), glow discharge optical emission spectroscopy (GDOES), fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). XRD has showed that the coatings are composed mainly of HA, rutile and anatase phases. The composition and surface morphologies are not strongly dependent on the applied voltages. The amount of HA deposited into the coating increases with increasing the applied voltage. The wear resistance of PEO-EPD coatings has been assessed using tribological tests. The bioactivity of the obtained coatings has been investigated in a simulated blood fluid.