Self-organizing evolution of anodized oxide films on Ti-25Nb-3Mo-2Sn-3Zr alloy and hydrophilicity

In the present work, hierarchical nanostructured titanium dioxide (TiO 2) films were fabricated on Ti-25Nb-3Mo-2Sn-3Zr (TLM) alloy for biomedical applications via one-step anodization process in ethylene glycolbased electrolyte containing 0.5wt% NH4F. The nanostructured TiO 2 films exhibited three distinct types depending on the anodization time: top irregular nanopores (INP)/beneath regular nanopores (RNP), top INP/middle regular nanotubes (RNT)/bottom RNP and top RNT with underlying RNP. The evolution of the nanostructured TiO2 films with anodization time demonstrated that self-organizing nanopores formed at the very beginning and individual nanotubes originated from underlying nanopore dissolution. Furthermore, a mod'ified two-stage self-organizing mechanism was introduced to illustrate the growth of the nanostructured TiO2 films. Compared with TLM titanium alloy matrix, the TiO2 films with special nano-structure hold better hydrophilicity and higher specific surface area, which lays the foundation for their biomedical applications. © 2014 Tianjin University and Springer-Verlag Berlin Heidelberg.