【作者】 张薇；

【导师】 崔彤；

【作者基本信息】 东北大学 ， 材料学， 2011， 硕士

【摘要】 近几十年来,生物医用金属材料在不断的发展与创新,多种新型材料被开发成功。镁合金做为生物医用植入材料有很多优于其他材料的性能。镁的密度、弹性模量等物理性能与人体骨组织接近,镁离子是人体所必须的微量元素之一。羟基磷灰石(HA)是骨骼、牙本质和牙釉质等硬组织的主要成分。把这两者结合到一起,即在镁合金表面涂覆HA涂层,既使得金属材料保持了良好的力学性能,又具备了优良的生物相容性。本课题根据生物相容性、力学相容性和可降解性能的要求自行优化设计了Mg-4.0Zn-0.5Sr及Mg-4.0Zn-1.5Sr二种合金,研究它们的降解性能。同时以Mg-4.0Zn-0.5Sr及Mg-4.0Zn-1.5Sr二种合金板材为基体,在其表面制备HA涂层。并对该材料的降解性能与生物相容性进行了研究。获得的实验结果如下：(1)自行设计了Mg-4.0Zn-0.5Sr及Mg-4.0Zn-1.5Sr二种合金,对镁合金锭坯进行均匀化退火后,道次间退火温度在300℃-400℃之间,同时道次压下量控制在10%-20%的轧制工艺条件下,进行高温到低温分阶段的轧制,轧制出了表面质量良好的1mm厚板材。并进行了175℃、8h的人工时效处理,其力学性能优良,抗拉强度达245MPa,同时硬度值达HV76.9,最大延伸率达到12.7%。(2)Mg-4.0Zn-0.5Sr、Mg-4.0Zn-1.5Sr合金板材做耐腐蚀性的对比实验,在SBF溶液降解实验中,它们的平均腐蚀速率分别为0.5527g/(m2·h)、0.6358g/(m2·h);它们的耐腐蚀能力大小是Mg-4.0Zn-0.5Sr>Mg-4.0Zn-1.5Sr。(3)以Mg-Zn-Sr合金板材为基体,利用前碱热处理+电沉积+后碱热处理方法在板材基体表面制备出了HA涂层,厚度约为44.45μm。在电沉积温度50℃,精确控制电压在3V时,得到涂层表面平整、致密,HA颗粒细小。(4)经HA涂层后,Mg-4.0Zn-0.5Sr及Mg-4.0Zn-1.5Sr合金板材SBF溶液中的其自腐蚀电位明显正移,自腐蚀电位正移50-200mV,其在SBF溶液中腐蚀速率均低于未涂层合金,耐腐蚀性能得到提高。(5)经碱活化镁合金板材表面后,经过CaCl2溶液和K2HPO4溶液的预钙化,并将预处理过的试样在SBF溶液中浸泡,促进了羟基磷灰石在镁合金表面的形核,按此工艺能够在镁合金板材表面快速诱导出HA涂层的生成。(6)Mg-4.0Zn-0.5Sr及HA涂层Mg-4.0Zn-0.5Sr合金的溶血率值为4.83%和3.57%,Mg-4.0Zn-1.5Sr及HA涂层Mg-4.0Zn-1.5Sr合金的溶血率值为4.63%和3.43%,均低于5.0%,具有良好的抗溶血性能。且HA涂层后其抗溶血性能提高,更适宜在人体中应用。同时浸提液的[Mg2+]浓度较低,说明HA涂层可降低初始[Mg2+]浓度,避免了局部[Mg2+]浓度的偏高而引起不良反应的现象。(7)通过细胞形态分析Mg-4.0Zn-0.5Sr及Mg-4.0Zn-1.5Sr合金以及经涂层后材料3ds细胞毒性的级别均为1级轻微细胞毒性。通过MTT检测结果分析,四种材料的细胞增殖度RGR%均在90～100%之间,亦说明其均为1级轻微细胞毒性。Mg-4.0Zn-0.5Sr合金涂层后其细胞的毒性略有降低。更多还原

【Abstract】 In recent decades, biomedical metallic material is in the continuous development and innovation, and many new materials are developed successfully. Because there are many advantages as biomedical implant materials, the study on magnesium alloys as one of attracted material become imperative. It is well known that the density and the elastic modulus of magnesium physical properties are very close to human bone tissue, as well as the magnesium ion is one of necessary trace elements of human body. Hydroxyapatite (HA) is the main ingredients of bone, tooth dentin and enamel etc. hard tissue essence. If HA is coated on the magnesium alloy surface, the composite material not keeps good mechanical properties but has excellent biocompatibility. Depended on biocompatibility, biomechanical compatibility and degradability, Mg-4.0Zn-0.5Sr and Mg-4.0Zn-1.5Sr alloy sheet were self-designed to study their degradability. After the HA coated on the Mg-4.0Zn-0.5r and Mg-4.0Zn-0.5r alloy sheet surface was prepared. The degradability and biocompatibility of the material were analyzed. Main results were as follows:(1)Optimal designed Mg-4.0Zn-0.5Sr and Mg-4.0Zn-1.5Sr alloys ingot was prepared to lmm thickness sheet through hot rolling between the anneal temperature of300℃～400℃from high temperature to low temperature after homogenizing. The reduction in very pass was controlled in10-20%. It had good mechanical properties after reasonable aging treatment, whose tensile strength can reach to245MPa, hardness can reach to HV76.9and maximum value of elongation rate can reach to12.7%.(2)The compared tests of corrosion resistance capability of Mg-4.0Zn-0.5Sr and Mg-4.0Zn-1.5Sr alloy sheet were carried out. In the SBF solution immersion test, their average corrosion rates were0.5527g/(m2-h) and0.6358g/(m2-h) respectively. The corrosion resistance capability Mg-4.0Zn-0.5Sr alloy was better than Mg-4.0Zn-1.5Sr alloy. (3)The Mg-4.0Zn-0.5Sr and Mg-4.0Zn-1.5Sr alloy sheet were used for the matrix by pre-alkali heat treatment, electro-deposition and latter alkali heat treatment process, and then the HA coating with the thickness about44.45μm was prepared. In50℃, the voltage was accurately controlled within3V, then the coated surface with smooth and dense is obtained.(4)The initial free corrosion potential of HA coating Mg-4.0Zn-0.5Sr and Mg-4.0Zn-1.5Sr alloy sheet shifted positively by200mV through electrochemical curve. And in the SBF solution immersion test, the initial corrosion rate was lower than the uncoated alloy sheet. It proved the initial corrosion resistance is improved.(5)HA coating was biomimetic deposited by activating the magnesium with dilute alkali solution firstly, then pretreated with the CaCl2solution and K2HPO4solution, and immersed in simulated body solution (SBF). Through the method hydroxyapatite can be rapidly induced nucleation in the magnesium alloy surface.(6)It took hemolysis rate test to study biocompatibility of Mg-4.0Zn-0.5Sr alloy sheet and Mg-4.0Zn-1.5Sr alloy sheet with HA coated. The hemolysis ratios of Mg-4.0Zn-0.5Sr and HA coating alloy sheet were4.83%and3.57%respectively, and the hemolysis ratios Mg-4.0Zn-1.5Sr and HA coating alloy sheet were4.63%and3.43%respectively. The hemolysis ratios were all lower than5.0%, which has a higher anti-hemolysis ability. Then hemolysis ratios of the HA coated alloys were increased through HA coating, which satisfied the requirement of bio-materials.(7)In3ds cytotoxicity test indicated that the cell toxicity of Mg-4.0Zn-0.5Sr, Mg-4.0Zn-1.5Sr and the HA coated alloy sheet were approximately at level one. The values of RGR of four materials were among90to100by means of MTT metabolism, which also prove all of the materials were approximately at level one. The cytotoxicity of Mg-4.0Zn-0.5Sr alloy with coating is decreases slightly.更多还原