Abstract: 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.

Key words: sol-gel method, TiO₂-SiO₂ film, NiTi alloy, surface modification, corrosion resistance