On Growth and Morphology of TiO<sub>2</sub> Nanotubes on Ti6Al4V by Anodic Oxidation in Ethylene Glycol Electrolyte: Influence of Microstructure and Anodization Parameters
Bruno Ribeiro,
Ruben Offoiach,
Ehsan Rahimi,
Elisa Salatin,
Maria Lekka,
Lorenzo Fedrizzi
Affiliations
Bruno Ribeiro
Lima Corporate, Via Nazionale 52, 33038 San Daniele del Friuli, Italy
Ruben Offoiach
Polytechnic Department of Engineering and Architecture, University of Udine, Via Cotonificio 108, 33100 Udine, Italy
Ehsan Rahimi
Polytechnic Department of Engineering and Architecture, University of Udine, Via Cotonificio 108, 33100 Udine, Italy
Elisa Salatin
Lima Corporate, Via Nazionale 52, 33038 San Daniele del Friuli, Italy
Maria Lekka
Polytechnic Department of Engineering and Architecture, University of Udine, Via Cotonificio 108, 33100 Udine, Italy
Lorenzo Fedrizzi
Polytechnic Department of Engineering and Architecture, University of Udine, Via Cotonificio 108, 33100 Udine, Italy
Different studies demonstrated the possibility to produce TiO2 nanotubes (TNTs) on Ti6Al4V alloy by electrochemical anodization. However, the anodizing behavior of α and β-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 β-phase as the higher Al content of the α-phase caused its re-passivation, and the higher solubility of the V-rich oxide led to earlier pores formation over the β-phase. The trend was inverted once the pores formed over the compact oxide of the α-phase. The growth rate of the α-phase TNTs was higher than that of the β-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 β-phase were individual, shorter, and with thicker walls.
