Study of the reactivity of a Ti-Cu(2%) alloy treated at different potentials in 5M phosphoric acid

A Ti-Cu(2%) alloy was anodically treated in a 5 M phosphoric acid bath at different potentials. XPS measurements showed that the passive film is mainly formed by an hydrated titanium oxide. Furthermore, the anodically treated samples present an excellent passivity in a potential domain extending from the corrosion potential to the treatment potential. Above the latter, the polarization curves present a current transition followed by a leveling off. This transition is not seen after performing a complete sweep. EDS measurements of the anodized samples revealed a decrease in oxygen content with the potentiodynamic polarization in H3PO4, despite the improvement in passivity.