Hydroxyapatite production on ultrafine-grained pure titanium by micro-arc oxidation and hydrothermal treatment

In this study, pure-Ti (Grade-2) was severely plastically deformed by equal-channel angular extrusion (ECAE) to improve its strength, and then subjected to micro arc oxidation (MAO) and hydrothermal treatment (HT) to achieve improved surface behavior with hydroxyapatite (HA)-containing titania (TiO(2)) coating. Microstructure, tensile properties and wear behavior of UFG Ti were investigated systematically before and after surface modification. ECAE considerably enhanced the strength of coarse-grained (CG) Ti by forming an ultra-fine grained (UFG) microstructure with high dislocation density. The application of MAO with or without HT did not cause remarkable decrease in strength and ductility of CG and UFG Ti, but resulted in a considerable increase in its wear resistance and osseointegration due to the formation of hard and adhered HA-containing TiO2 coating on the surface. It can be concluded that the use of ECAE plus MAO/HA coating provides a simple and effective procedure to obtain pure Ti with high strength and high wear resistance. The improved bulk and surface properties can make this biocompatible material a good potential candidate for biomedical applications instead of alloys including toxic elements. (C) 2011 Elsevier B.V. All rights reserved.