[Characterization of surface films formed on titanium in electrolytic solutions]

In order to understand the interface-phenomena between titanium and biological tissue, the surface film formed on titanium in electrolytic solutions was examined using X-ray photoelectron spectroscopy (XPS). The composition of the surface film on titanium before immersion into solution is close to TiO2 and that of Ti-6 Al-4 V is a mixture of TiO2 and Al2O3. These surface films change to a complex phosphate of titanium and calcium containing hydroxyl radicals and hydrates when the specimens are immersed in an electrolytic solution. The compositions of the surface films of titanium and Ti-6 Al-4 V are almost the same except that the film on Ti-6 Al-4 V is thicker and contains more hydrates than that on titanium. Vanadium in Ti-6 Al-4 V, and sodium, chlorine, and sulfur in the solution are not responsible for the formation of the films.