Surface structure of Ti-O films formed on pure titanium by anodic oxidation

Abstract

The formation of Ti-O thin films on pure titanium was carried out by anodic oxidation, not only to improve the corrosion resistance of the material but also to form stable coating in passive state with the adsorption site for the BMP(Bone Morphogenetic Protein) on the material, aiming at the clinical use of the material as a carrier or a substratum for the BMP. Furthermore the effects of electrolytic voltage ranging from 110V to 220V for the anodic oxidation on the formation of Ti-O films on the pure titanium were investigated by analysing the surface morphology, the layer composition and the structural property. The sparking voltage was about 160V on the pure titanium material. On the treatment below the sparking voltage, the Ti-O films formed by anodic oxidation was thin and optically interferential, while above the sparking voltage, thick Ti-O films having many pin-holes ranging from 0.1 to 0.3 micrometer in diameter as well as fine craters ranging from 2 to 3 micrometer in diameter were formed on the treated surface. According to Auger electron spectroscopy (AES) in-depth profiles, it was found that the Ti-O films formed above the sparking voltage was around 10 times thicker than those formed below the sparking voltage. On the basis of X-ray diffraction (XRD), it was concluded that the titanium oxide of anatase phase was formed in both the films formed by anodizing below and above the sparking voltage.