医用NiTi合金表面溶胶-凝胶法制备TiO2-SiO2薄膜

采用溶胶－凝胶法在ＮｉＴｉ形状记忆合金表面制备了ＴｉＯ_２－ＳｉＯ_２复合薄膜，在提高医用ＮｉＴｉ合金的抗腐蚀性方面，收到了显著的效果．运用电化学方法对不同组成的ＴｉＯ_２－ＳｉＯ_２薄膜在模拟体液中的腐蚀行为进行了研究，结果表明，随薄膜中 Ｔｉ／Ｓｉ比的增加，ＴｉＯ_２－ＳｉＯ_２薄膜的抗腐蚀性增强．划痕试验表明 ＴｉＯ_２－ＳｉＯ_２（Ｔｉ／Ｓｉ＝４：１）膜与ＮｉＴｉ合金基体具有较高的界面结合强度．用原子力显微镜（ＡＦＭ）对ＴｉＯ_２－ＳｉＯ_２薄膜的表面形貌及表面粗糙度进行观察和分析，解释并讨论了ＴｉＯ_２－ＳｉＯ_２薄膜的配方组成与其抗腐蚀性的关系，ＳｉＯ_２含量较少时，薄膜结构致密，膜层均匀平滑，且膜基结合力好，作为医用ＮｉＴｉ合金的表面保护层，可以使其耐腐蚀性有显著提高．

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.