Corrosion of metallic biomaterials in the human body is a commonly overlooked phenomenon, even though it constitutes a serious risk for
implant failure. Nevertheless, a fundamental understanding of the electrochemical reactions occurring at the interface biomaterial/human
body fluid is necessary in order to successfully engineer surfaces on titanium biomedical alloys, the most widely used solution for bone
repair and joint replacement. Cp-Ti (ASTM grade 2) and Ti6Al4V (ASTM grade 5) present good mechanical properties, corrosion
resistance 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, namely the inability to actively
regulate osteoblast behavior or battle colonization by pathogenic microorganisms. In this regard, the anodization of titanium is a simple
and effective surface treatment that has the potential to improve both osteointegration and antimicrobial activity.
The aim of this work is to investigate the effect of the anodizing parameters and post anodizing heat treatment of medical grade Cp-Ti and
Ti6Al4V, on their corrosion resistance through potentiodynamic polarization measurements in a simulated body fluid solution. Titania
nanotubes, obtained by anodization in an ethylene glycol electrolyte containing 0.5wt.% NH4F and 2.5% V H2O at different applied
potentials and different anodization times, have been characterized regarding their morphology and structure. The distinct geometry of the
nanotubes and their increased surface area are believed to lead to an improvement in osseointegration. Their particular tubular shape
makes them, in addition, excellent reservoir for antimicrobial agents. Post anodizing heat-treatments can develop a crystalline
microstructure that closely resembles that of the native hydroxyapatite on the human bone. Nevertheless, the anodization and the post
anodization heat treatment can influence the corrosion resistance of the Ti alloys in the human body. The aim of this work is to
understand how the process parameters can influence the microstructure and thus the corrosion resistance, in order to avoid a decrease
of the corrosion properties.
