Affiliations: Department Stomatology, Zhejiang Medical University, Hangzhou, 310009, P.R. China | Centre for Biomedical Materials Application and Technology, National University of Singapore, Singapore 119260 | Department of Materials Science and Engineering, University of Cincinnati, OH 45221, USA
Abstract: In vitro corrosion resistance and ion dissolution of commercial pure titanium with different surface microroughness are studied adopting constant potential meter and atomic absorption spectroscopy. In terms of the surface roughness, titanium samples are divided into 5 groups: smooth surface, machining surface, 2 different microroughness surfaces and macrorough surface. Each group contains three category samples under different treatments: natural oxidation (24 h exposure to air), oxidation under 400^{\circ}C (400^{\circ}C, 45 min thermal oxidation), oxidation under 700^{\circ}C (700^{\circ}C, 45 min thermal oxidation). In Hanks corrosion media, comparative studies through constant potential anode polarization curves and titanium release rates of the 5 groups of Ti samples demonstrates that oxidation under 400^{\circ}C best increase corrosion resistance and decrease ion release sharply, oxidation under 700^{\circ}C is better than natural oxidation. Ti samples with a different surface roughness all have good corrosion resistance and their corrosion resistance drop with the raising of surface roughness. Comparing with macrorough surface and machining surface, microrough surfaces have better corrosion resistance and a lower ion release rate which are similar to those of smooth surfaces. Moreover, the corrosion resistance of machining surface Ti is the lowest. It is hypothesized that surface treatment methods such as surface thermal oxidation, surface aging and so on will improve the corrosion resistance and decrease the ion release rate of rough surface effectively by increasing the thickness of surface protection film, improving its structural uniformity and facilitating the formation of ordered, compact surface protection film.
Keywords: Electrochemistry, corrosion resistance, in vitro test, ion release, microrough surface, titanium, thermal oxidation
