Effects of Alloying Elements on the HAp Formability on Ti Alloys after Alkali Treatment

抄録

This work presents a study on the relationship between the alloying elements such as niobium (Nb), tantalum (Ta) or zirconium (Zr) and the hydroxyapatite (HAp) formability on the surfaces of titanium (Ti) alloys subjected to alkali treatment process that is developed to form a HAp layer. The HAp formability on the surfaces of pure Ti, Ti–Nb alloys, Ti–Ta alloys, Ti–Zr alloys, pure Nb, pure Ta and pure Zr subjected to alkali treatment in 1 mol/L NaOH solution at 363 K for 259.2 ks was investigated.
The pure Ti, Ti–10Nb alloy and Ti–10Zr alloy have a good HAp formability because sodium titanate is formed on the surface after the alkali treatment. However, the HAp formability is decreased with increasing Nb and Zr contents. A layer including sodium titanate and sodium tantalate is formed on the surfaces of Ti–Ta alloys after the alkali treatment. Therefore, the Ti–10Ta, Ti–20Ta, Ti–30Ta and Ti–40Ta alloys have a good HAp formability. On the other hand, a sodium niobate layer and a thick crystalline sodium tantalate layer are formed on the surfaces of pure Nb and pure Ta, respectively, after the alkali treatment. Moreover, there is no component change on the surface of pure Zr after the alkali treatment. Therefore, the HAp formability on the surfaces of pure Nb, pure Ta and pure Zr is significantly low after they are soaked in a simulated body fluid for 1 week.