On Growth And Morphology Of Tio2 Nanotubes On Ti6al4v By Anodic Oxidation In Ethylene Glycol Electrolyte: Influence Of Microstructure And Anodization Parameters

Different studies demonstrated the possibility to produce TiO2 nanotubes (TNTs) on Ti6Al4V alloy by electrochemical anodization. However, the anodizing behavior of alpha and beta-phases in organic electrolytes is not yet clarified. This study reports on the anodizing behavior of the two phases in an ethylene glycol electrolyte using different applied potentials and anodizing times. Atomic force and scanning electron microscopies were used to highlight the anodic oxides differences in morphology. It was demonstrated that the initial compact oxide grew faster over the beta-phase as the higher Al content of the alpha-phase caused its re-passivation, and the higher solubility of the V-rich oxide led to earlier pores formation over the beta-phase. The trend was inverted once the pores formed over the compact oxide of the alpha-phase. The growth rate of the alpha-phase TNTs was higher than that of the beta-phase ones, leading to the formation of long and well defined nanotubes with thin walls and a honeycomb tubular structure, while the ones grown over the beta-phase were individual, shorter, and with thicker walls.