细薄壁镁合金管材塑性成形技术及生物相容性研究

发布时间：2018-01-13 16:28

  本文关键词：细薄壁镁合金管材塑性成形技术及生物相容性研究　出处：《沈阳工业大学》2017年硕士论文　论文类型：学位论文

  更多相关文章： Mg-Y-Nd-Zr合金 力学性能 静态腐蚀 细胞毒性 热处理

【摘要】：目前随着心血管疾病对人类健康的严重威胁,血管支架的植入变得更加广泛,但是现在的血管支架多以不锈钢、镍钛合金等不可降解的支架为主,由于不可降解支架在人体中造成的二次损害,镁合金作为一种新型的生物可降解材料引起了人们的广泛关注,而稀土镁合金具有的良好的力学性能和低的生物毒性成为了无可比拟的优势。本文对具有良好生物相容性的稀土镁合金为研究对象,通过对Mg-Y-Zr合金中添加不同含量的稀土Nd元素,探究出Nd对稀土镁合金的力学性能,微观组织,耐蚀性能及细胞毒性的影响规律,获得力学性能和生物相容性较好的血管支架用的镁合金基材,通过热挤压和拉拔的方式制备细薄壁血管支架,并探究出了合理的管材热处理制度。通过对Mg-4Y-0.5Zr合金中添加不同含量的稀土Nd元素发现随着Nd的含量由0%增大到6%,Mg-4Y-x Nd-0.5Zr合金的抗拉强度先增大后减小。当Nd含量为3%时,合金的抗拉强度最大达到193MPa,Mg-4Y-xNd-0.5Zr合金的伸长率随着Nd含量的增加一直减小,当Nd含量为0%时,合金的伸长率最高达到9%;对Mg-4Y-xNd-0.5Zr合金进行静态浸泡实验,发现随着含Nd量的增加,合金的平均腐蚀速率先减小后增大,当Nd含量为3%时,合金的平均腐蚀速率最低,为0.039mg/cm2h,Nd含量为4.5%时,合金的平均腐蚀速率最高为6.63mg/cm2h;对腐蚀后的合金进行腐蚀形貌观察,当不含Nd时,合金发生主要是局部腐蚀,随着Nd含量的增加,合金腐蚀为均匀腐蚀,当Nd含量达到6%时,合金腐蚀最为严重。对AM50、Mg-4Y-4.5Nd-0.5Zr、Mg-4Y-6Nd-0.5Zr、Mg-4Y-3Nd-0.5Zr四种镁合金的体外细胞实验发现,四种合金浸提液的细胞毒性较低,其对脐静脉内皮细胞的活性基本没有影响。在24h的浸提过程中,Mg-4Y-4.5Nd-0.5Zr合金呈现出较快的降解行为,表面出现较多的蚀坑,离子溶出较多。Mg-4Y-3Nd-0.5Zr合金的离子溶出较少,呈现出较好的耐蚀性。合金表面的细胞植入实验发现,Mg-4Y-4.5Nd-0.5Zr和Mg-4Y-6Nd-0.5Zr合金表面由较多的枝状腐蚀产物形成,其附着在细胞表面或周围,影响细胞的活性。AM50和Mg-4Y-3Nd-0.5Zr合金的腐蚀产物较少,但是相对而言,Mg-4Y-3Nd-0.5Zr合金表面的细胞生长状态更好。采用合理的挤压参数,对Mg-4Y-3Nd-0.5Zr合金进行热挤压管材实验,得到表面质量良好的管材,对挤压管材进行T5和T6处理后,管材的抗拉强度在225℃×14h时效处理下抗拉强度最高达到286MPa;管材经过525×8h+225℃×14h固溶时效处理后,管材的综合性能良好,管材的抗拉强度达到269MPa,伸长率为13.8%;通过对挤压管材进行10道次拉拔,拉拔速度为0.2mm/s,退火温度为400℃,保温10min,可拉拔出外径为4mm,壁厚为0.25mm的管材,管材壁厚均匀。
[Abstract]:At present, with the serious threat of cardiovascular disease to human health, vascular stent implantation has become more widespread, but the current stent is mainly stainless steel, nickel titanium alloy and other non-degradable stent. Magnesium alloys as a new biodegradable material have attracted wide attention due to the secondary damage caused by non-degradable scaffolds in human body. The rare earth magnesium alloy with good mechanical properties and low biotoxicity has become an unparalleled advantage. This paper has a good biocompatibility of rare earth magnesium alloys as the research object. The effects of ND on the mechanical properties, microstructure, corrosion resistance and cytotoxicity of rare earth magnesium alloys were investigated by adding different contents of rare earth ND into Mg-Y-Zr alloys. Magnesium alloy substrate with good mechanical properties and biocompatibility was obtained and thin wall vascular stent was prepared by hot extrusion and drawing. The reasonable heat treatment system of pipe was investigated. By adding different contents of rare earth ND to Mg-4Y-0.5Zr alloy, it was found that with the increase of ND content from 0% to 6%. The tensile strength of Mg-4Y-x Nd-0.5Zr alloy first increases and then decreases. When ND content is 3, the maximum tensile strength of Mg-4Y-x Nd-0.5Zr alloy is 193MPa. The elongation of Mg-4Y-xNd-0.5Zr alloy decreases with the increase of ND content. When the content of ND is 0, the elongation of Mg-4Y-xNd-0.5Zr alloy reaches 9%. The static immersion test of Mg-4Y-xNd-0.5Zr alloy shows that the average corrosion rate of Mg-4Y-xNd-0.5Zr alloy decreases first and then increases with the increase of ND content, when the ND content is 3. When the average corrosion rate of the alloy is 0.039 mg / cm ~ (-2) ND = 4.5, the average corrosion rate of the alloy is 6.63 mg / cm ~ (-2) h. The corrosion morphology of the corroded alloy is observed. When there is no ND, the alloy is mainly localized corrosion. With the increase of ND content, the alloy corrosion is uniform, and when the ND content reaches 6%, the alloy corrosion is uniform. The corrosion of the alloy is the most serious. For AM50 Mg-4Y-4.5Nd-0.5Zr, Mg-4Y-6Nd-0.5Zr. In vitro cell experiments of four kinds of Mg-4Y-3Nd-0.5Zr magnesium alloys showed that the cytotoxicity of the four kinds of alloy extracts was relatively low. Mg-4Y-4.5Nd-0.5Zr alloy showed a faster degradation behavior and more pits on the surface during 24h extraction. The ion dissolution of Mg-4Y-3Nd-0.5Zr alloy was less and showed better corrosion resistance. Cell implantation on the surface of the alloy was found. The surface of Mg-4Y-4.5Nd-0.5Zr and Mg-4Y-6Nd-0.5Zr alloys is formed by more dendritic corrosion products and adheres to or around the cell surface. The corrosion products affecting cell activity. AM50 and Mg-4Y-3Nd-0.5Zr alloy were few, but relatively speaking. The cell growth state of Mg-4Y-3Nd-0.5Zr alloy surface is better. The hot extrusion tube experiment of Mg-4Y-3Nd-0.5Zr alloy is carried out with reasonable extrusion parameters. After treated with T5 and T6, the tensile strength of the extruded tube was up to 286 MPA under 225 鈩，

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