Long-term corrosion resistance of new Ti–Ta–Zr alloy in simulated physiological fluids by electrochemical and surface analysis methods

• Native passive film (TiO2, Ta2O5, ZrO2) on Ti–15Ta–5Zr alloy surface has a thickness of 8.5 nm.
• Duplex oxide film formed by inner, compact and by outer porous layer was modelled by EIS.
• Passive film thickened over time by new depositions from physiological solutions.
• After 1500 h in acid Ringer solution the brushite was detected by XPS.
• In neutral and alkaline Ringer solutions the hydroxyapatite was identified by XPS and SEM.

The native passive film on the new Ti–15Ta–5Zr alloy surface contains the protective TiO2, Ta2O5 and ZrO2 oxides (XPS analysis). The decrease of the corrosion current densities and the increase of the polarisation resistances values signify the thickening of the passive film in time. The duplex oxide film formed by the inner, compact, layer and by the outer, porous layer was modelled; electrical parameters indicated the thickening over time both of the barrier and porous layers. XPS and SEM analyses demonstrated the in time deposition of new layers consisting by brushite in acid Ringer solution and from hydroxyapatite in neutral and alkaline Ringer solutions.

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