生物可降解Ca-P陶瓷颗粒增强镁基复合材料研究

发布时间：2018-01-03 18:15

本文关键词：生物可降解Ca-P陶瓷颗粒增强镁基复合材料研究　出处：《天津理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：重量轻、力学性能适宜、生物安全性高并可降解的镁及镁合金材料在骨修复器材、血管支架和止血夹等可降解植入材料方面孕育着巨大的临床应用前景,但镁及镁合金在含有Cl-的生理环境中存在着降解速率过快的问题,因此可能带来力学强度下降过快,p H值的升高以及氢气产生等问题,这些问题是目前该类材料走向临床应用的主要障碍。针对这一关键问题,本文采用复合化的形式,通过在镁合金基体中添加Ca-P陶瓷颗粒,从而起到细化镁合金基体晶粒以及提高基体的力学性能和耐蚀性能的作用。本文首先通过控制冷却速率制备了不同晶粒大小的纯镁,采用真空熔炼制备了Mg-30%Ca合金,分别研究了晶粒尺寸和第二相对镁合金腐蚀降解行为的影响。采用高剪切搅拌工艺制备1HA/Mg-3Zn-0.2Ca及1β-TCP/Mg-3Zn-0.2Ca复合材料,采用光学显微镜(OM)、扫描电子显微镜(SEM)、透射电镜(TEM)、X射线衍射分析(XRD)从不同尺度观察表征显微组织;采用电化学测试的方法对合金及复合材料的腐蚀行为进行研究,采用热模拟实验研究增强相的添加对Mg-Zn-Zr合金热变形行为的影响,将高剪切熔炼所制备的铸态试样采用等通道转角挤压(ECAE)进行变形处理,研究等通道转角挤压对复合材料的显微组织、织构及电化学行为的影响。主要结论为:1.随着晶粒尺寸的减少,晶粒细化可以使镁的腐蚀敏感性增加,但阻抗及浸泡实验表明,细晶镁在浸泡的过程中可以产生更致密的钝化层,因此镁基材料具有更好的耐腐蚀性。2.对于Mg-Ca合金来说,研究表明Mg2Ca相在基体中会作为阳极被优先腐蚀与一般镁合金中的第二相的作用有所不同。Mg-30wt%合金的长时间浸泡实验(90d)表明,在合金浸泡腐蚀降解的后期会产生一些难降解的腐蚀产物,这些腐蚀产物是具有包覆结构的微粒。3.HA和β-TCP的添加可以有效的细化Mg合金的晶粒,由于β-TCP与Mg基体具有更小的错配度,所以其细化作用更加明显。HA和β-TCP的添加还可以使镁合金在浸泡过程中的钝化层更具有保护性从而提高Mg基材料的耐腐蚀性。4.Mg-3Zn-0.8Zr合金以及HA/Mg-3Zn-0.8Zr复合材料的热模拟实验表明:在小于573K时,Mg-3Zn-0.8Zr合金的变形机制主要为位错攀移控制的蠕变机制,大于623K时则部分转变为晶界滑动的变形机制,HA的添加则可以部分抑制晶界滑动变形机制的产生。并且HA的添加可以提高Mg-3Zn-0.8Zr合金在高温下的峰值应力,这种情况的发生可能是由于晶粒尺寸减小或者晶内分布的HA阻碍位错运动造成。5.等通道转角挤压可以使铸态1HA/Mg-Zn-Ca复合材料的晶粒得到细化,而且HA颗粒的团簇尺寸也随着变形道次的增加而减少,复合材料的显微组织更加均匀,ECAE的挤压过程可以使试样的ED面部分上与Mg晶格的基面平行,由于镁晶格的基面具有更高的结合能,因此1HA/Mg-Zn-Ca复合材料的ED面具有更好的耐腐蚀性。
[Abstract]:Light weight, suitable mechanical properties, magnesium and magnesium alloy material with high biological safety and degradable in bone repair equipment, stent and clip etc. biodegradable implant materials has enormous clinical application prospects, but magnesium and magnesium alloy in physiological environment containing Cl- exists the problem of excessive degradation rate therefore, the mechanical strength may bring down too quickly, the p value of H and increase the hydrogen production, these problems are the main obstacle of this kind of materials to clinical application. To solve this problem, this paper adopts the composite form, through adding ceramic particles in Ca-P magnesium alloy matrix, so as to refine magnesium alloy matrix grain and improve the mechanical properties and corrosion resistance of the matrix. The effect of the pure magnesium with different grain size control the cooling rate of preparation of Mg-30% Ca alloy was prepared by vacuum melting method, The effects of grain size and the relative second magnesium alloy corrosion behavior were studied. The high shear mixing process and the preparation of 1HA/Mg-3Zn-0.2Ca 1 beta -TCP/Mg-3Zn-0.2Ca composite materials by using optical microscope (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X ray diffraction analysis (XRD) to observe the microstructure characterization from different scale; research on Corrosion Behavior of alloy by electrochemical method and composite materials, the thermal simulation experiment of reinforcement effect on deformation behavior of Mg-Zn-Zr alloy, high shear melting prepared by as cast samples by equal channel angular pressing (ECAE) deformation processing, microstructure of composite materials the study of ECAP, the effect of texture and electrochemical behavior. The main conclusions are as follows: 1. with the decrease of grain size, grain refinement can make the corrosion sensitivity of magnesium increased, But the impedance and immersion test showed that the passivation layer of fine grained magnesium can produce more dense in the soaking process, so magnesium based materials have better corrosion resistance for.2. Mg-Ca alloy, research shows that long time immersion test Mg2Ca as anode was the second priority and general corrosion in magnesium alloy phase in the matrix the effect of different.Mg-30wt% alloys (90d) show that in the late immersion corrosion degradation will produce some refractory corrosion products, the corrosion product is added with grain coating structure of the particle.3.HA and beta -TCP can refine Mg alloy effectively, because the beta -TCP and Mg matrix has a smaller mismatch so, adding the refinement effect is more obvious.HA and beta -TCP can also make the magnesium alloy passivation layer during the immersion is more protection in order to improve the corrosion resistance of.4.Mg-3Zn-0.8Zr Mg Composites Show that the thermal simulation experiment of gold and HA/Mg-3Zn-0.8Zr composite materials: in less than 573K, the deformation mechanism of Mg-3Zn-0.8Zr alloy is dislocation climb creep mechanism controlling the displacement of more than 623K, is partly transformed into the deformation mechanism of grain boundary sliding, the addition of HA can partially inhibit the grain boundary sliding deformation mechanism. The peak and the addition of HA improve Mg-3Zn-0.8Zr alloy under high temperature stress, this may happen due to the reduction of grain size or grain distribution of HA by hindering the movement of dislocation can make grain cast 1HA/ Mg-Zn-Ca composite materials were refined.5. and ECAP, the cluster size of HA particles with deformation times decrease and the microstructure of the composites is more uniform and the extrusion process of ECAE can make the basal part of the sample on the ED surface and the Mg lattice parallel to the magnesium base lattice The mask has a higher binding energy, so the 1HA/Mg-Zn-Ca composite's ED mask has better corrosion resistance.

【学位授予单位】：天津理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB333

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