不同电解液体系下Mg-2Sr合金表面微弧氧化膜层的制备与生物相容性研究

发布时间：2018-03-17 22:32

本文选题：镁合金　切入点：微弧氧化　出处：《山东大学》2017年硕士论文　论文类型：学位论文

【摘要】：作为潜在的生物医用可降解植入体材料,镁合金具有以下优点:密度及弹性模量与人体骨组织较为接近,能有效的减少应力遮蔽效应,适用于骨组织修复及替代,从而促进骨组织生长;骨骼系统中的镁有利于骨生长及骨强度的提高,其溶解过程不产生任何副作用。然而,镁在人体内的降解速度过快,无法在新骨组织长成之前完成支撑任务。降解产生的氢气聚集在植入体周围,阻碍了伤口愈合,同时也提高了植入体周围组织的pH值,甚至发生碱中毒。镁的提纯,合金化及表面改性可以作为增强耐蚀性的三种不同解决方法。本实验采用锶元素合金化制备性能优良的Mg-2Sr合金,随后制备微弧氧化膜层,实现合金化和表面改性的结合。本文的研究内容为不同电解液体系下Mg-2Sr合金表面微弧氧化膜层的制备与生物相容性研究。具体的,首先自行浇铸Mg-2Sr合金基体;其次对比了不同聚乙二醇含量的膜层的性能,并给出最佳添加量数值;随后研究了有机钙源(葡萄糖酸钙,乳酸钙)和无机钙源(碳酸钙,氢氧化钙)对微弧氧化膜层的组织结构,电化学行为和体外降解行为的影响;最后选择优化的钙源乳酸钙和碳酸钙,研究了钙磷摩尔比对微弧氧化膜层组织结构与生物活性的影响。结果表明,Mg-2Sr合金中的一部分锶元素和镁结合生成中间化合物,另一部分锶元素则以固溶体的形式存在于合金中,合金的实际成分为Mg-2.24Sr。聚乙二醇的加入使得微弧氧化膜层的厚度略有降低且差别不大,含有8g/L的PEG1000电解液体系制备的膜层具有最大的结合力,为15.75N,且具有最强的耐蚀性及最低的降解速率,浸泡前2天内,试样出现了增重的现象。以有机钙源和无机钙源制备的微弧氧化膜层浸泡后出现了 Ca_2P_2O_7(CCP),Mg(OH)_2,HA 和 Ca_(10-x)Sr_x(PO_4)_6(OH)_2(Sr-HA)等新的物相,Ca_(10-x)Sr_x(PO_4)_6(OH)_2相是元素Sr取代了羟基磷灰石中元素Ca的位置而形成的一种新的生物相容性磷灰石,该相可以促进骨植入体周围细胞的生长、繁殖和修复。以乳酸钙为钙源制备的膜层在SBF浸泡后的表面颗粒状腐蚀产物中钙磷相含量较高。以碳酸钙为钙源,钙磷比为1:4和1:5的膜层的腐蚀产物中出现了沿腐蚀裂纹分布纳米棒和纳米线状的物质,两种钙源下钙磷比为1:4的膜层在SBF中浸泡21天后的失重率仅有13%,这利于保证植入体在体内环境的力学稳定性。
[Abstract]:As a potential biomedical biodegradable implant, magnesium alloy has the following advantages: density and modulus of elasticity are close to human bone tissue, can effectively reduce stress shielding effect, and can be used for bone tissue repair and replacement. Magnesium in the bone system is beneficial to bone growth and bone strength, and does not cause any side effects. However, magnesium degrades too quickly in the human body. The hydrogen generated by the degradation accumulates around the implant, hinders wound healing, increases the pH value of the tissue around the implant, and even causes alkalosis. Alloying and surface modification can be used as three different solutions to enhance corrosion resistance. In this experiment, Mg-2Sr alloys with excellent properties were prepared by strontium alloying, and then micro-arc oxide films were prepared. In this paper, the preparation and biocompatibility of micro-arc oxide film on Mg-2Sr alloy surface under different electrolyte systems were studied. Firstly, the substrate of Mg-2Sr alloy was cast by itself. Secondly, the properties of the film with different polyethylene glycol content were compared, and the optimum addition value was given. Then, the organic calcium sources (calcium gluconate, calcium lactate) and inorganic calcium sources (calcium carbonate) were studied. The effect of calcium hydroxide on the structure, electrochemical behavior and degradation behavior of the micro-arc oxide film. Finally, the optimized calcium sources calcium lactate and calcium carbonate were selected. The effects of Ca / P molar ratio on the microstructure and bioactivity of the microarc oxide film were studied. The results showed that some strontium elements in Mg-2Sr alloy combined with magnesium to form intermediate compounds, and the other strontium elements existed in the alloy as solid solution. The actual composition of the alloy is Mg-2.24Sr.The addition of polyethylene glycol makes the thickness of the micro-arc oxide film slightly lower and the difference is not obvious. The PEG1000 electrolyte system containing 8g / L has the greatest adhesion. Is 15.75Nand has the strongest corrosion resistance and the lowest degradation rate, within 2 days before soaking, After soaking in the micro-arc oxide film prepared by organic and inorganic calcium sources, Ca2P2O7C / C / C _ 2O _ 7 / C / C / C _ 2O _ 7 / C _ 2O _ 7 / C _ 2O _ 7 / C _ 2O _ 7 / C _ 2O _ 7 / C _ 2O _ 7 / C _ 2O _ 7 / C _ 2O _ 7 / C _ 2O _ 7 / C _ 2C _ 2O _ 7 / C _ 2C _ 2C _ 2C _ H _ 2C _ H _ 2H _ H _ 2H _ H _ 2H _ H _ 2, etc., new phases such as Ca10 ~ (-x) -x ~ (-) Sr _ (x) O _ (4) O _ (4) O _ (6) O _ (-HAH), etc. A new biocompatible apatite, This phase can promote the growth, reproduction and repair of the cells around the bone implants. The calcium phosphate phase in the coating prepared by calcium lactate as calcium source is higher in the surface granular corrosion products after immersion in SBF, and calcium carbonate is used as calcium source. Nanorods and nanowires distributed along corrosion cracks were found in corrosion products of films with Ca / P ratios of 1: 4 and 1: 5. The weight loss rate of the film with Ca / P ratio of 1: 4 to 1: 4 immersed in SBF for 21 days was only 13% under two calcium sources, which was helpful to ensure the mechanical stability of the implant in vivo.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.4

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