富氧气氛下钛合金加工表面氧化膜形成及其生物相容性研究

发布时间：2018-04-01 18:01

本文选题：绿色切削　切入点：钛合金植入体　出处：《山东大学》2016年博士论文

【摘要】：医用钛合金因具有良好的力学、物理、化学性能及出色的生物相容性,成为了人造关节,牙植入体及骨创伤产品等硬组织替代物及修复物的首选材料。钛及钛合金植入体在植入之前需要进行表面改性,以提高其耐腐蚀性及生物活性。目前国内外钛合金植入体的表面改性方法均是在机械加工成形之后,其缺点是工艺链长、工艺设备复杂、效率低、成本高。鉴于此,本研究提出了一种切削加工成形与表面改性于一体的钛合金植入体制备新方法；利用切削加工产生的切削热进行表面氧化改性,提高其耐腐蚀性；利用切削加工形成的特定表面形貌提高其生物活性。从可持续发展的角度开发出一种针对钛合金植入体的新型绿色切削加工制备方法,对缩短工艺链、提高效率、降低成本、保护环境、提高钛合金植入体制造技术水平和产品竞争力有重要作用。主要研究工作如下：首先,基于氧化热力学研究钛合金氧化膜产生的机理,确定形成致密二氧化钛膜的条件。基于物理化学理论,分析钛合金氧化过程中钛离子和氧离子的运动规律,揭示钛合金氧化速度的主要控制因素。研究结果表明：形成致密二氧化钛氧化膜的最佳温度范围为600-900℃,此温度范围内钛合金氧化速度的主要控制因素为氧离子通过氧化膜的扩散速度。其次,基于菲克第一定律及阿列纽斯公式建立钛合金氧化动力学模型,研究影响氧化速度的主要因素。采用MATLAB对钛合金氧化动力学模型进行计算,分析各因素对氧化速度的影响规律。研究结果表明：影响钛合金氧化速度的主要因素为氧化温度、富氧浓度及富氧压力、晶粒细化程度及氧化膜厚度；提高氧化温度、富氧浓度及富氧压力、晶粒细化程度可加速钛合金的氧化,但氧化膜厚度的增加会降低钛合金氧化速度。然后,搭建富氧气氛下切削加工工艺试验平台,采用Deform 3D有限元仿真软件对切削参数进行优化,将切削温度控制在最佳氧化温度范围。进行不同切削参数及不同富氧气氛下切削加工试验,对钛合金加工表面氧化膜成分和厚度,表面形貌及表层晶粒进行表征,分析切削温度,富氧浓度和晶粒细化程度等因素对氧化速度的影响规律。将试验结果与理论结果对比,富氧气氛下切削加工能够显著提高钛合金加工表面氧化膜的厚度及致密性,验证了氧化动力学模型的正确性。最后,对富氧气氛下切削加工表面进行耐腐蚀性及生物活性评价。通过模拟体液浸泡试验及电化学腐蚀试验,研究富氧气氛下切削钛合金表面的腐蚀机理和主要影响因素。通过体外细胞培养,观测细胞的黏附、铺展、增殖、分化及矿化等细胞行为,研究加工表面的生物活性,分析加工表面对细胞行为的调控机理。研究结果表明：富氧气氛下切削加工生成的氧化膜能够显著提高钛合金的耐腐蚀性,而且表面形成的微/纳复合结构面形貌有利于蛋白质的吸附,对细胞的黏附,铺展,增殖等细胞行为有较好的调控作用,显著提高了钛合金的生物活性。
[Abstract]:Medical titanium alloy has good mechanical, physical and chemical properties, biocompatibility and excellent biological, has become the preferred material for artificial joints, dental implants and bone trauma products hard tissue substitute and prosthesis. Titanium and titanium alloy implants require surface modification before implantation, in order to improve its resistance biological activity and corrosion. The surface of titanium alloy at home and abroad of the implant modification methods are after mechanical forming, its disadvantage is the process of chain length, complex process equipment, low efficiency and high cost. In view of this, this study proposes a new method of machining and forming titanium alloy implant surface preparation modified in one of the heat generated by cutting; cutting the surface oxidation modification, improve its corrosion resistance; specific surface morphology formed by cutting to improve its bioactivity. The development from the perspective of sustainable development A new type of green machining system for titanium alloy implant preparation method, to shorten the process chain, improve efficiency, reduce costs, protect the environment, improve the titanium alloy implant manufacturing technology level and product competitiveness has an important role. The main research work is as follows: firstly, based on the mechanism of oxidation of titanium oxide film produced by thermodynamics, to determine the formation of dense titania film. The physical and chemical conditions based on the theory analysis of the motion law of the oxidation process of titanium ions and oxygen ions, the main control reveals the oxidation rate of titanium alloy. The results show that: the optimum temperature range to form a dense oxide film of titanium dioxide is 600-900 DEG C, the main controlling factors of titanium alloy oxidation rate in this temperature range the oxygen ion diffusion through the film speed. Secondly, Fick's first law and Alexyevna Arrhenius formula is set up based on the oxidation of titanium alloy Dynamic model, study main factors affecting the oxidation rate. Using MATLAB to calculate the titanium alloy oxidation kinetics model, analysis of effects of different factors on the oxidation rate. The results show that the main factors affecting the oxidation rate of titanium alloy for the oxidation temperature, oxygen concentration and oxygen pressure, the grain size and film thickness; improve the oxidation temperature, oxygen concentration and oxygen pressure, the degree of grain refinement can accelerate the oxidation of titanium alloy, but the increase of film thickness will reduce the oxidation rate of titanium alloy. Then, the experiment platform in cutting process under oxygen rich atmosphere, the cutting parameters were optimized by using Deform finite element simulation software 3D, the cutting temperature control in the optimal oxidation temperature range cutting test. Different cutting parameters and different oxygen enriched atmosphere, the composition and thickness of oxide film on titanium alloy surface processing, table The grain surface morphology and surface characterization, analysis of influence factors of cutting temperature, oxygen concentration and the degree of grain refinement on the oxidation rate. The experimental results and theoretical results of oxygen enriched atmosphere cutting can increase the thickness and density of the oxide film on the surface of titanium alloy processing, to verify the correctness of the oxidation kinetics model. Finally, to evaluate the corrosion resistance and biological activity of oxygen enriched atmosphere cutting surface. Through the SBF test and electrochemical corrosion test, and the main factors which influence the corrosion mechanism of the surface machining of titanium alloy on the oxygen enriched atmosphere. The cell culture, cell adhesion, observation spreading, proliferation, differentiation and mineralization of cell behavior study on the processing surface, biological activity, analysis of regulation mechanism of machined surface on cell behavior. The results show that: oxygen enriched atmosphere cutting processing The oxide film can significantly improve the corrosion resistance of titanium alloy, and the surface micro / nano composite surface morphology is conducive to protein adsorption, and has a good regulation effect on cell adhesion, spreading, proliferation and other cell behaviors, significantly improving the bioactivity of titanium alloy.

【学位授予单位】：山东大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG174.4;R318.08

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