Structural, Morphological, and Electrochemical Corrosion Properties of TiO2 Formed on Ti6Al4V Alloys by Anodization

In this work, TiO2 layers are synthetized on Ti6Al4V alloy substrate by electrochemical anodizing process in fluoride-containing alkaline electrolytes and under different applied voltages (10, 20, and 30 V). The scanning electron microscopy (SEM) reveals a nearly regular and vertical alignment of TiO2 nanotubes (approximate to 80-100 nm) for specimen treated at 20 V and an agglomerate of particles with no particular orientations for those specimens treated at 10 and 30 V. The X-ray diffraction (XRD) indicates the formation of mixed phases of anatase and rutile. Wettability measurements exhibit hydrophilic and superhydrophilic surfaces, according to the anodization parameters. The electrochemical impedance spectroscopy (EIS), performed in a simulated body fluid (Hank's solution), reveals an increase in corrosion resistance for a bias potential of 20 V (262 k omega) owing to the evolution in TiO2-layer thickness, and then decreases for higher anodizing potential values due to the chemical dissolution of the obtained layer.