Effect of anodizing parameters on the formation of TiO2 nanotubes produced on titanium grade 2 and titanium grade 5

Ti-based implants are the most widely used solution for bone repair and joint replacement, due to the favorable properties of titanium and its alloys when compared to other commonly used metals, namely, stainless steel and cobalt-chromium alloys. In short, titanium grade 2 and titanium grade 5 present good mechanical properties and biocompatibility without showing toxicity or immune rejection. However, although the inertness of titanium has been considered a favorable characteristic for years, its lack of bioactivity also presents some challenges, regarding inability to actively regulate osteoblast behavior or battle colonization by pathogenic microorganisms. Titanium anodization is a simple and effective surface treatment for the improvement of osteointegration and antimicrobial activity. Extensive work has been performed on the study of the production titania nanotubes on the surface of commercially pure titanium (grade 2) but little work exists on the production of TI nanotubes on the surface of Ti6Al4V (grade 5) alloy the most widely used alloy in orthopedic implants. The aim of this work is to produce and characterize titania nanotubes on the surface of Ti gr.2 and gr. 5 using different anodizing parameters. An ethylene glycol electrolyte containing 0.5wt.% NH4F and 2.5% V H2O was used for the anodization at room temperature. The applied voltage varied from 20 to 120V and the anodization time from 30 to 180 min. The obtained films have been characterized by SEM and XRD regarding the microstructure with particular attention to the structure of TiO2 nanotubes on the α and β phase grains of Ti6Al4V.