Electrochemical corrosion behaviors of titanium covered by various TiO₂ nanotube films in artificial saliva

TiO₂ nanotube films obtained by anodization have shown great promise as biomaterials. In the present work, we report on the corrosion behaviors of titanium (Ti) with various TiO₂ nanotubes prepared by using controlled anodization procedures. Special emphasis is put on the impact of film morphologies on the corrosion resistance of the Ti substrate. The corrosion behaviors of Ti with different nanotube films were studied in artificial saliva using open-circuit potential measurement, potentiodynamic polarization, and electrochemical impedance spectroscopy techniques. Ti covered by TiO₂ nanotube films showed the markedly enhanced corrosion resistance properties compared to bare Ti. The existence of the compact oxide layer formed in a fluoride-free electrolyte was found to be beneficial for improving corrosion resistance properties. Besides, the TiO₂ nanotube films obtained by two-step anodization had better corrosion resistance than those obtained by single-step anodization, though they used the identical anodization parameters.