Fatigue strength of Ti-6Al-4V alloy with surface modified by TiO2 nanotubes formation

Highly ordered arrays of TiO2 nanotubes are being considered as very promising to improve the osseointegration of titanium based implants to living tissues. However, this improvement must be accompanied by no drawback in the mechanical properties, which is the case of several surface modification techniques available for biomaterials. Therefore, this work investigated for the first time the effect of the surface modification by TiO2 nanotubes formation on the fatigue response of Ti-6Al-4V biomedical alloy. Highly organized nanotubes with an average diameter and length respectively of 90 and 600nm were successfully produced by electrochemical anodization. Based on the standardized staircase method, fatigue tests of the treated specimens were conducted in physiological media at 37°C, and compared to the untreated polished specimens. The mean and standard deviation values of the fatigue limit calculated through the Dixon-Mood equations were equal for both surface conditions. This result suggests that the employed condition of anodization was satisfactory on growing a nanotubes coating that was not deleterious to the fatigue performance of the alloy, what is a relevant achievement that assures the possibility of having high osseointegration and at the same time keeping the mechanical properties.