生理环境下医用NiTi合金微磨损-腐蚀协同作用机制研究

As implant material, NiTi shape memory alloy would be corrode by human body fluid and wear by other implant material or human bone. So the implant material would further damage and loss, and the service life would reduce. According to the medical phenomena and facts, a new theory of the synergistic effect between micro-abrasion and corrosion of NiTi alloy in different simulated body fluids has been proposed. In order to prove the theory, NiTi alloy with different phase compositions by heat treatment will be used to study the correlation between electrochemical corrosion, micro-abrasive wear, micro-wear and corrosion and the microstructure of alloy. The relationship will be determined using electrochemical corrosion and micro-abrasive wear technology. It is expected that the mechanism for the formation of wear mode in the process of micro-wear-corrosion will be unveiled. The principles for microstructural control of the NiTi alloy for improving micro-wear-corrosion resistance will be put forward. A theory system concerning the effect of microstructure at different heat treatment on micro-wear-corrosion of NiTi alloy will be constructed. The outcome of the project is not only directive for microstructural optimization and micro-wear-corrosion control of the NiTi alloy but also beneficial to the use of NiTi alloy as implant material in medical.

NiTi形状记忆合金作为人体植入材料植入到人体内后，在受到人体体液腐蚀的同时会与植入件或人骨发生磨损，从而加剧植入件的破坏进而流失，降低植入件的使用寿命。针对这一医学现象和事实，提出“生理环境下医用NiTi合金微磨损-腐蚀协同作用机制研究”的研究命题。围绕该命题，以自制NiTi形状记忆合金为主要研究对象，以电化学腐蚀和微磨粒磨损为主要研究手段，通过不同热处理控制合金的组织构成，研究合金在不同组织构成下的电化学腐蚀行为和微磨损行为及微磨损-腐蚀行为，揭示合金在微磨损-腐蚀过程中磨损机制的形成机理，提出改善合金耐微磨损-腐蚀的组织控制原则和建立磨损图的理论依据，构筑基于合金的热处理制度而形成的不同组织构成对合金微磨损-腐蚀行为影响的理论体系。研究成果不仅对NiTi合金的组织优化和微磨损-腐蚀控制有重要指导意义，还对其在医学上作为人体植入材料的使用有重要的参考价值。

本项目以在金属植入医疗器械在人体体液中的磨损作为研究背景，以典型生物医用NiTi合金和新型Ti-25Nb-3Mo-3Zr-2Sn (TLM)合金为研究对象，采用电化学腐蚀和微磨损相结合的方法，系统地研究了不同组织状态的NiTi合金的电化学腐蚀、微磨损和腐蚀-磨损及TLM合金的腐蚀-磨损行为；重点研究腐蚀与磨损的协同作用及其对材料流失行为的影响；阐释了不同组织状态下NiTi合金的微磨损与电化学腐蚀之间的对应关系；阐明了NiTi合金和TLM合金在模拟生理环境下的微磨损-腐蚀协同作用机制，以及NiTi合金组织状态对应的腐蚀-磨损行为；同时基于材料流失和腐蚀磨损之间的协同作用，建立腐蚀-磨损图（腐蚀-磨损机制图、材料流失图和腐蚀-磨损协同作用图）；研究成果为基于不同生理环境下的植入假体等人体植入材料的选择及腐蚀磨损防护提供理论指导。