Influence of the oxidizing technique on the biocompatible and corrosion properties of Ti6Al4V in a physiological environment

• Blue oxides generated by anodization and plasma treatment were investigated. • Anodized specimen had better corrosion resistance than plasma treated specimen. • Vanadium enrichment at outermost oxide surface of plasma treated specimen. • Outermost oxide of plasma treated specimen is highly porous. • Oxide formed by anodization is more biocompatible than plasma treated one. This work aims to evaluate the corrosion and biocompatibility properties of oxide films generated on Ti6Al4V alloys using both traditional and novel methods. Oxide films were generated by anodization and plasma treatment to achieve a blue surface finish. The oxide films were then characterized and compared to a native film formed on the Ti6Al4V. Electrochemical tests, incorporating potentiodynamic tests and electrochemical impedance spectroscopy, were employed to define the electrochemical resistance of oxides in an environment simulating biological exposure. In vitro tests were conducted to study ion release and biocompatible properties over a 6-week period of exposure to a 0.9 wt% NaCl solution, at body temperature. Various spectroscopic techniques, including ToF-SIMS, XRD, and Raman analysis, were used to study the structure and chemistry of the oxide films. The sub-surface layer was analysed by microstructural investigation. The type of oxidation was found to have a key influence on the oxide composition, especially with respect to the depth distribution of the individual alloy elements through the oxide film. The oxidation process determines which of the alloying elements are released into the environment, as a result of the corrosion reactions.