One-Step Approach for the Fabrication and Characterization of Hydroxyapatite/TiO2 Composite Ceramic Coatings by Micro-Arc Oxidation In Situ on the Surface of Pure Titanium

The hydroxyapatite (HA)/ TiO2 composite ceramic coatings were formed by micro-arc oxidation (MAO) on pure titanium in mixed electrolyte of calcium glycerophosphate and calcium acetate with DC pulse power. Microstructure, phase composition, porosity and thickness of the coatings were examined using SEM, XRD, Image-Pro Plus 6.0 Image analysis system and Eddy current thickness gauge. Results indicate that MAO coatings containing calcium and phosphorus were formed in situ on pure titanium surface. Pores formed by the discharge channels distribute uniformly on the coatings surface, and the inner layer is dense. The principal crystalline phases of the MAO coatings are anatase TiO2, rutile TiO2, HA, Ca3(PO4)2 and matrix Ti. The interface is metallurgical bonding and the bonding strength is strong. And reaction time makes a greater influence than voltage in thickness and voltage makes a greater influence than time in porosity.