Abstract
An electrochemical method was established for achieving apatite formation on the surfaces of Ti and its alloys in simulated body fluid (SBF). Crystalline titania layers are formed on pure Ti, Ti-6Al-4V, Ti-6Al-2Nb-1Ta and Ti-15Mo-5Zr-3Al alloy surfaces when these alloys are anodized in H2SO4 solutions of different concentrations and at different applied voltages. The anodically oxidized substrates form a dense and uniform bone-like apatite layer on their surfaces in SBF that contains ions in concentrations similar to those present in human body blood plasma. The apatite formation on the surfaces of Ti and its alloys in SBF is proposed to be induced and nucleated by the lattice-matching relationship of the crystal structures between the apatite and rutile phases in the titania layers. As the surface morphology of titania layers on anodically oxidized Ti and its alloys is a three-dimensional, open, porous structure, the resultant surface structure can provide strong adhesive strength between the apatite layer and the substrates. Therefore, use of the described anodic oxidation is expected to result in Ti and its alloys being suitable for use in bioactive implant materials, even under load-bearing conditions.
