Bioactivity of hybrid micro/nano-textured Ti-5Si surface by acid etching and heat treatment

The surfaces of the Ti-5Si specimens tested in this study displayed micro-pores and a nano-textured structure after being etched with a H2SO4 solution. After immersion in a simulated body fluid (SBF) solution for 7 days, numerous apatite nucleation spheres were found on the outer and inner surfaces of the micro-pores after acidetching and acid-heat treatments. Apatite precipitation was clearly observed on the surfaces of the Ti-5Si specimens without heat treatment, suggesting that heat treatment is not necessary for apatite precipitation on the surface of Ti-5Si that has undergone the acid etching process. Additionally, there was apatite formation on the surface of the as-cast Ti-5Si specimens that were soaked in SBF solution for 14 days, although the ability of as-cast Ti-5Si alloy to form apatite was slightly lower than that of its acid-etched or acid-heat-treated counterparts. This acid treatment has the potential to enhance the bioactivity of Ti-5Si and is expected to be able to strengthen the fixation of the implant with bone through a hybrid micro/nano-textured surface. Therefore, it can be concluded that etching in sulfuric acid is an effective and simple surface treatment for Ti-5Si alloy destined for biological applications. (C) 2016 Elsevier Ltd. All rights reserved.