Nickel-titanium alloys have been investigated for applications to various surgical procedures. However, little is known about the toxicity of Ni-elements and the actual conditions of surface modification of Ni-Ti alloy for preventing the toxicity of Ni. In this study, the corrosion resistance of Ni-Ti alloys was improved through producing a thin TiO 2 film by conducting in-air oxidation and reactive sputtering. These thin films were characterized using field emission type scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and atomic force microscopy. Using the polarization curves obtained by electro-chemical measurements in quasi-living body environment, the corrosion resistance of Ni-Ti super elastic alloy was evaluated. In addition, the effect of an air-oxidized Ni-Ti alloy specimen upon cell multiplication and morphological change of cell were investigated by culturing cells for 72 hrs on a Ni-Ti alloy specimen surface with TiO2 thin film. From these considerations, some trials for establishing a method for TiO 2 thin film formation on the surface of Ni-Ti alloy were conducted from the view point of improving biocompatibility.

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