双连续钛—镁复合材料设计制备与表征

发布时间：2018-04-19 19:17

  本文选题：多孔钛 + 钛-镁复合材料　； 参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：钛及钛合金以其高的比强度、良好的耐蚀性和生物相容性等优点已成为目前具有发展潜力的一种生物医用材料,但是钛及钛合金存在着的最大的两个不足便是:弹性模量过高(TC4合金弹性模量为110GPa),会产生“应力屏蔽”效应;钛属于生物惰性材料,但是不能诱导促进骨组织的生长。镁合金以其较低的弹性模量、良好的骨整合性和骨诱导性以及可降解性等优点也成为发展前景广阔的一种生物医用材料,但是镁合金耐腐蚀性较差、强度较低成为了限制其发展的最大瓶颈。本论文以开发一种低弹性模量、强度高、在人体内可以起到承载作用并具有较好的生物相容性且新型生物医用材料为目的。利用低弹性模量的多孔钛和具有良好的骨整合性与骨诱导性的镁,将镁通过超声波辅助浸渗的方法渗入多孔钛的孔隙中制备出了钛-镁复合材料。为了在原材料选用和加工制备过程中不引入有害元素,因此选用高纯球形钛粉利用烧结的方法来制备多孔钛。通过不同工艺参数的烧结实验研究了钛粉尺寸、烧结压力、烧结温度、烧结时间和烧结路径对多孔钛形貌和性能的影响规律,优化出多孔钛的烧结工艺为:900℃保温50min后进行简单清洁加工,然后进行1200℃烧结120min,获得孔隙质量好、表面清洁、强度高的多孔钛。采用超声波辅助浸渗的方式,利用超声波的“空化”作用提高钛和镁之间的润湿性,获得了结构致密的钛-镁复合材料。通过扫描电子显微镜(SEM)、X射线衍射(XRD)的表征发现钛和镁在室温下基本不互溶且不存在第二相。钛和镁的界面结合致密,存在扩散层,提高了界面结合强度。双连续钛-镁复合材料继承了作为骨架的多孔钛的力学性能特征。镁的加入起到了对材料的稳定和强化作用。钛颗粒粒径分别是230μm、130μm和100μm的复合材料的弹性模量为23.4GPa、33.6GPa和37.6GPa,压缩屈服强度分别为230.2MPa、262.9MPa和300.1MPa,抗弯强度为375.2MPa、468.8MPa、631.5MPa。弹性模量在人骨的弹性模量水平,可避免“应力屏蔽”效应,压缩屈服强度和抗弯强度均高于人骨的强度,因此可以满足在人体内的承载服役要求。由于钛镁的复合,材料内形成了原电池,因此材料的耐腐蚀性被降低。镁被选择性腐蚀留下孔隙,可以为骨组织生长和营养物质的运输提供空间,且腐蚀产物镁离子为人体的常量元素。因此钛-镁复合材料具有良好的生物相容性,但是耐腐蚀性有待进一步研究来提高,首先商业纯镁的耐蚀性差,其次钛和镁的直接复合形成电偶腐蚀加速镁的腐蚀。利用直接氧化的方法在钛和镁的界面上形成一层氧化层,但由于其连续性较差而且不能完全阻止钛和镁之间的扩散,对材料的耐蚀性没有明显的改善,复合材料的力学性能由于钛氧化层的引入而有所降低但仍然满足性能要求,因此证明了只要选用合适的扩散障层,该方法是可行的。
[Abstract]:Titanium and titanium alloys have become a kind of biomedical materials with high specific strength, good corrosion resistance and biocompatibility. However, titanium and titanium alloy have two biggest shortcomings: the high elastic modulus of TC4 alloy is 110 GPA, which will produce "stress shielding" effect, and titanium is a biological inert material, but it can not induce the growth of bone tissue. Magnesium alloys have become a promising biomedical material for their low modulus of elasticity, good bone integration, bone induction and degradability, but magnesium alloys have poor corrosion resistance. Low intensity has become the biggest bottleneck limiting its development. The purpose of this paper is to develop a new biomedical material with low elastic modulus, high strength, good biocompatibility and bearing capacity in human body. Using porous titanium with low modulus of elasticity and magnesium with good bone integration and bone induction, titanium magnesium composites were prepared by infiltration of magnesium into the pores of porous titanium by ultrasonic infiltration. In order to avoid the introduction of harmful elements in the selection and preparation of raw materials, high purity spherical titanium powder was used to prepare porous titanium by sintering. The effects of titanium powder size, sintering pressure, sintering temperature, sintering time and sintering path on the morphology and properties of porous titanium were studied by sintering experiments with different technological parameters. The sintering process of porous titanium was optimized as follows: 1: 900 鈩，

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