Pan J, Leygraf C, Thierry D, Ektessabi A M
Department of Materials Science and Engineering, Royal Institute of Technology, Stockholm, Sweden.
J Biomed Mater Res. 1997 Jun 5;35(3):309-18. doi: 10.1002/(sici)1097-4636(19970605)35:3<309::aid-jbm5>3.0.co;2-l.
The high corrosion resistance and good biocompatibility of titanium and its alloys are due to a thin passive film that consists essentially of titanium dioxide. There is increasing evidence, however, that under certain conditions extensive titanium release may occur in vivo. An ion-beam-assisted sputtering deposition technique has been used to deposit thick and dense TiO2 films on titanium and stainless steel surfaces. In this study, using the following measurements these TiO2 films have been investigated in a phosphate-buffered saline solution: (1) open-circuit potential versus time of exposure, (2) electrochemical impedance spectroscopy, (3) potentiodynamic polarization, and (4) Mott-Schottky plot. A higher electrical film resistance, lower passive current density, and lower donor density (in the order of 10(15) cm-3) have been measured for the sputter-deposited oxide film on titanium in contrast to the naturally formed passive oxide film on titanium (donor density in the order of 10(20) cm-3). The improved corrosion protection of the sputter-deposited oxide film can be explained by a low defect concentration and, consequently, by a slow mass transport process across the film. As opposed to TiO2 on titanium, a deviation from normal n-type semiconducting Mott-Schottky behavior was observed for TiO2 on stainless steel.
钛及其合金具有高耐腐蚀性和良好的生物相容性，这归因于一层主要由二氧化钛构成的薄钝化膜。然而，越来越多的证据表明，在某些条件下体内可能会发生大量钛释放。一种离子束辅助溅射沉积技术已被用于在钛和不锈钢表面沉积厚而致密的二氧化钛薄膜。在本研究中，利用以下测量方法在磷酸盐缓冲盐溶液中对这些二氧化钛薄膜进行了研究：（1）开路电位与暴露时间的关系，（2）电化学阻抗谱，（3）动电位极化，以及（4）莫特-肖特基图。与钛表面自然形成的钝化氧化膜（施主密度约为10²⁰ cm⁻³）相比，在钛上溅射沉积的氧化膜测得具有更高的膜电阻、更低的钝化电流密度和更低的施主密度（约为10¹⁵ cm⁻³）。溅射沉积氧化膜改善的耐腐蚀性能可以用低缺陷浓度来解释，因此也可以用穿过该膜的缓慢质量传输过程来解释。与钛上的二氧化钛不同，在不锈钢上的二氧化钛观察到偏离正常n型半导体莫特-肖特基行为。
