Preparation of TiO2-SiO2 Films on Biomedical NiTi Alloy by a Sol-Gel Method

Sol-gel-derived TiO2-SiO2 films on NiTi Shape Memory Alloy were prepared. The corrosion behavior of TiO2-SiO2 films with different compositions was studied in Tyrode's solution. The results indicate that the corrosion resistance will be enhanced with the increasing of Ti/Si molar ratio in the film. A scratching test and AFM observation show that the TiO2-SiO2 film (Ti/Si=4:1) is bonded strongly to the substrate. AFM analyses of surface morphology and roughness indicate that the TiO2-SiO2 film (Ti/Si=4:1) is compact, uniform and smooth. The relationship between the composition and corrosion resistance of TiO2-SiO2 films was discussed. The TiO2-SiO2 films with a small amount of SiO2 have good corrosion resistance and can be used as protective layers on NiTi alloy for biomedical applications.