抗菌不锈钢在生理环境中的界面结构演变及其对抗菌性能的影响

Cu-bearing stainless steels are a new class of medical metal materials, based on the antibacterial mechanism of Cu ions release from the surface of stainless steels. Passive film is a key factor to control the release of Cu ions and to decide if the stainless steel has excellent antibacterial function. From the view point of understanding the structure character of passive film, study on the rule of the structural evolution of passive film in physiological environment and antibacterial property will have the scientific importance to better understanding the antibacterial mechanism of Cu-bearing stainless steel and optimizing the antibacterial material design. On the basis of previous research work, after obtaining the thermodynamic curves of Cu-rich phase precipitation and sensitization of 316LCu stainless steel, proper aging treatment and passive potential will be defined by methods of potentiostatic polarization and antibacterial test, and a material model containing proper passive film structure will be constructed. The dissolution and repair behavior of the passive film on the Cu-bearing stainless steel will be emphatically analyzed by three aspects: the change of interface structure, the change of electrochemical properties and the properties change related to the antibacterial performance. Furthermore, the related influence mechanism of structure evolution of passive film on antibacterial property will also be clarified. The corresponding relation among the Cu-rich precipitation, the dissolution and repair of passive film and the antibacterial performance will be preliminarily built. The above research results will provide a theoretical foundation to further optimize the material design for Cu-bearing antibacterial stainless steels.

含Cu抗菌不锈钢是基于Cu离子释放为抗菌机制的新型医用金属材料，而表面钝化膜是控制Cu离子释放从而保证其具备优异抗菌功能的关键。从掌握含Cu不锈钢表面钝化膜的结构特点出发，研究其在体内环境中的结构演变及与抗菌性能的变化规律，对于更好地理解其抗菌作用机制并优化抗菌不锈钢的材料设计具有重要的科学意义。本项目在前期研究工作基础上，通过316LCu抗菌不锈钢中富Cu析出相的析出动力学和敏化动力学研究，结合恒电位极化方法和抗菌性能测试作为判据，制定合理的时效处理制度和钝化电位，构建含Cu不锈钢表面钝化膜模型。重点从界面结构变化、电化学特性变化和抗菌相关特性变化三个方面解析含Cu不锈钢表面钝化膜在生理环境中的溶解和修复行为，阐明含Cu不锈钢表面钝化膜界面的结构演变与抗菌性能的相关作用机制，初步建立富Cu相-钝化膜溶解和修复-抗菌性能之间的对应关系，为含Cu抗菌不锈钢的材料优化设计提供理论依据。

本项目以含铜不锈钢为研究对象，系统研究了316L-Cu不锈钢在不同时效温度下富铜相的析出行为和界面偏析现象。并以力学性能、耐蚀性能及抗菌性能为判据，获得了最优的热处理制度。同时制定合理的化学钝化方法和电化学钝化电位，着重考察了铜对不锈钢表面钝化膜组成及电子结构的影响规律，发现表面钝化膜的化学组成包括氧化铬、纯铜和氧化铜，其中铜和氧化铜在钝化膜中的体积分数对于抗菌性能和耐蚀性能具有重要的调控作用，合适的比例能同时保证含铜不锈钢具有优异的耐蚀性能和抗菌持久性。此外，通过电化学测试及表面元素分析检测方法证实了含铜不锈钢钝化膜在长时服役过程中呈现出溶解与修复的博弈过程，其中铜元素是引发该过程的关键，也正是由于博弈过程的存在，使得含铜不锈钢能够在腐蚀性介质中维持良好耐蚀性的同时具备抗菌长效性。并且本项目深入探讨了含铜不锈钢与细菌之间的交互作用关系，揭示了含铜不锈钢能够通过抑制细菌呼吸产能将细菌灭活，初步建立起富Cu相-钝化膜溶解和修复-抗菌性能之间的对应关系，为含Cu抗菌材料的材料优化设计提供了科学理论依据。