Preparation and Properties of TiO₂ Nanotubes

In order to make titanium based metals fit for the implant environment of human body and improve the wettability and corrosion resistance,TiO₂ nanotubes were prepared on the surface of titanium by anodic oxidation method at 25 V of DC voltage using NH₄F and ethylene glycol as electrolyte.The effects of anodic oxidation time on morphology,phase compositions,wettability and corrosion resistance of TiO₂ nanotubes were studied.The morphology and phase compositions of TiO₂ nanotubes were characterized by scanning electron microscopy（ SEM） and X-ray diffraction（ XRD）. Distilled water contact angle of the samples was measured by contact angle measuring instrument,and the corrosion resistance of the samples was studied by a potentiodynamic polarization curve method.The results show that when the oxidation time is 2 h,highly ordered TiO₂ nanotubes with pore size range of about 30 ~40 nm and pore wall thickness of about 20 nm can be prepared on the titanium surface. Contact angle between the titanium sheet and distilled water is about 28.8° indicating a better wettability.Furthermore,the self-corrosion voltage of titanium with TiO₂ nanotubes is 0.145 V,about 34% higher than that of pure titanium. The corrosion current is about 0. 468 μA/cm²,and the corrosion resistance Rpis about 1. 023×10⁵Ω/cm² for sample with TiO₂ nanotubes,significantly improving the corrosion resistance.