Oxidation behavior and effect of layer thickness on whiteness and exfoliation behavior of oxide film formed on Ti-Nb-Ta-Zr alloy

Metallic materials for dentistry such as Ti alloys, the Pt group or Au group alloys have excellent mechanical properties as a load bearing material, however, they are inferior in point of esthetic. Ti-29Nb-13Ta-4. 6Zr alloy is β-type Ti alloy with excellent mechanical property as a biomedical load-bearing material, and on which it is found that a firm yellowish-white oxide layer is formed by heat treatment at a particular temperature. Therefore, the detailed study regarding the oxide film formation in Ti-29Nb-13Ta-4. 6Zr and its properties will be interesting in terms of biomedical applications. In the present study, the oxide formation behavior investigation was carried out with focusing on oxide exfoliation behavior and esthetic property. Our recent results revealed that multilayer oxide film covers Ti-29Nb-13Ta-4. 6Zr substrate, and which each layer has different color. From cross sectional observation, a dense white oxide layer formed on top, and whose thickness increased with increasing heat treatment temperature and duration time. CIELab measurement results suggest that L^* increases with increasing layer thickness.