Improved corrosion and adhesion properties of titanium alloy for endoprostheses applications using a two-step anodization method

To promote adherence, hydrophilicity and corrosion properties, TiO2 nanotubes, compact TiO2 films and a combination of them were formed on Ti6Al4V alloy using only electrochemical methods. Nanostructured arrays being largely studied, the work was focused on the compact layer and the effect of the additional anodization. Corrosion results in physiological conditions were supported by surface and cross-section observations to choose the best protective treatment. Contact angles were measured to have an idea of osseointegration properties. The ageing of the surface reducing the hydrophilicity, two activation treatments were proposed to recover the good initial values. Finally, interfacial adhesion was evaluated by tensile tests. Corrosion and adhesion properties of the nanotube layer (ipass: 16 μA·cm−2, pull-out surface: 100 %) can be significantly improved by the second anodization (ipass: 0,12 μA·cm−2, pull-out surface: 0 %) that seals the bottom of the tube by an underneath compact oxide layer, preserving their hydrophilicity property.