Sol-gel derived bioactive hydroxyapatite/titania composite films on Ti6Al4V

The composite films consisting of the titania gel impregnated with hydroxyapatite (HAP) submicron particles were prepared on commercial Ti6Al4V plates processed by a sol-gel route. HAP powders were synthesized based on wet chemical precipitation method with Ca(NO₃)₂·4H₂O and (NH₄)₂HPO₄ as starting reagents. After being calcined at 900°C,HAP powders were ultrasonically scattered in ethanol to produce HAP sol. The titania sol was prepared using titanium (IV) isopropoxide {Ti[OCH(CH₃)₂]₄} as precursor. Both the titania sol and the HAP/titania mixture were sequentially spin-coated on the substrates and calcined at various temperatures. The characteristics and mechanical adhesion of the composite films were investigated. The results show that the as-prepared films are dense,homogeneous,well-crystallized,and there is a good interfacial adhesion between the film and the substrate. The in vitro bioac-tivities of these films were discussed based on the analysis of the variations of Ca and P concentrations in the simulated body fluid and their surface morphologies against immersion time.