Electrochemical characteristics of nanotubes formed on Ti–Nb alloys

Titanium and Ti alloys have been used extensively as bone-implant materials due to their high strength-to-weight ratio, good biocompatibility and excellent corrosion resistance. In this work, we have investigated the effects of the β-stabilizing element Nb on the morphology of nanotubes formed on Ti–xNb alloys using 1.0 M H3PO4 electrolyte containing 0.8 wt.% NaF and various electrochemical methods. Oxide layers consisting of highly ordered nanotubes with a wide range of diameters (approximately 55–220 nm) and lengths (approximately 730 nm–2 μm) can be formed on alloys in the Ti–xNb system as a function of Nb content. The nanotubes formed on the Ti–Nb alloy surface were transformed from the anatase to rutile structure of titanium oxide. The titanium oxide nanotube surface was observed to have lower corrosion resistance in 0.9% NaCl solution compared to titanium oxides surfaces on Ti–xNb alloys without the nanotube morphology.