Hydroxyapatite and brushite coatings on plasma electrolytic oxidized Ti6Al4V alloys obtained by the thermal substrate deposition method

Abstract Hydroxyapatite (HA) and brushite (DCPD) coatings were prepared on plasma electrolytic oxidation (PEO)-treated Ti6Al4V substrates using thermal substrate deposition (TSD) technology. For the deposition of calcium phosphate (CaP) coatings of different phase compositions, the temperature-dependent solubility phenomenon of calcium orthophosphates at a fixed solution pH was used. DCPD and calcium-deficient HA (Ca/P = 1.64) coatings were obtained at substrate temperatures of 85 °C and 140 °C, respectively. For 30 min of deposition, a 300 μm thick HA coating consisting of both needle- and plate-shaped crystals of 4 μm and a 50 μm thick DCPD coating with needle-like crystals of 7 μm were obtained. Porous morphologies were characteristic of both coatings.