Relationship between the properties of an interlayer formed by in situ Ti anodization and anaphoretically deposited hydroxyapatite

The optimization of the anodization process of Ti substrate for in situ synthesis of hydroxyapatite/titanium oxide composite coatings on titanium substrate was accomplished. The anodization was performed under 30, 60 and 90 V cell voltage, and the morphology of treated surface, as well as linear and surface roughness, were analysed by field emission-scanning electron microscopy, atomic force microscopy and roughness tester. It was shown by linear and surface roughness analyses that titanium anodized under 60 V has the highest roughness, whereas at 90 V the flattening of the surface occurs. As the highest surface roughness results emerged at 60 V, the novel process of composite anHAp/TiO2 coating synthesis, which comprises simultaneous processes of TiO2 formation and HAp deposition, as well as HAp impregnation within TiO2 surface layer, was performed at this voltage. Ti substrate surface was completely covered by composite coating, with no visible cracks. The adhesion quantified according to ASTM D3359-02 standard is considerably improved with respect to the coatings obtained by cathaphoretic processes, with no need of subsequent sintering.