Surface Oxide Films on Titanium Alloys Regenerated in Hanks’ Solution

Abstract

Titanium and some of its alloys are successfully used for biomaterials. The surface oxide films on these materials play important roles in maintaining corrosion resistance and biocompatibility. In this study, Ti–6Al–4V, Ti–56Ni, and Ti–xZr (x=0, 25, 50, 60, 75, 100) alloys in mass% were abraded and kept for 300 s in water and Hanks’ solution. The regenerated surface oxide film in Hanks’ solution was characterized using X-ray photoelectron spectroscopy. As a result, phosphate ions were preferentially taken up in the surface oxide film during regeneration. Ions constituting Hanks’ solution other than calcium and phosphate were absent from the surface oxide film. In the case of titanium and Ti–6Al–4V, calcium phosphate was formed on/in the surface oxide film regenerated in Hanks’ solution. However, Ti–56Ni, Ti–Zr, and zirconium did not form calcium phosphate on themselves but formed phosphate without calcium. These results are in good agreement with those for titanium alloys immersed in Hanks’ solution.