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1、独创性声明 本人声明所呈交的学位论文是本人在导师指导下进行的研究工作和取得的研究成果，除了文中特别加以标注和致谢之处外，论文中不包含其他人已经发表或撰写过的研究成果， 也不包含为获得 天津大学天津大学 或其他教育机构的学位或证书而使用过的材料。 与我一同工作的同志对本研究所做的任何贡献均已在论文中作了明确的说明并表示了谢意。 学位论文作者签名： 签字日期： 年 月 日 学位论文版权使用授权书 本学位论文作者完全了解 天津大学天津大学 有关保留、使用学位论文的规定。特授权 天津大学天津大学 可以将学位论文的全部或部分内容编入有关数据库进行检索，并采用影印、缩印或扫描等复制手段保存、汇编以供查阅和
2、借阅。同意学校向国家有关部门或机构送交论文的复印件和磁盘。 （保密的学位论文在解密后适用本授权说明） 学位论文作者签名： 导师签名： 签字日期： 年 月 日 签字日期： 年 月 日 摘摘 要要 医用镁及镁合金具有良好的力学相容性、生物相容性、生物降解性以及骨诱导能力，有望成为新一代可降解骨植入材料。然而，镁及镁合金在含有 Cl-的环境中可发生快速降解， 破坏材料的力学完整性， 同时产生大量氢气造成皮下气肿，限制了临床应用。因此，研发具有可控降解能力的镁及镁合金材料具有重要的意义，而表面涂层技术是目前提高镁及镁合金耐蚀性的一种有效手段。 本文以溶胶-凝胶浸渍提拉技术，在 AZ31 镁合金基体表面
3、制备 45S5 生物玻璃陶瓷涂层及 45S5 生物玻璃陶瓷/羟基磷灰石 （HA） 复合涂层。 通过 SEM、 XRD和 FTIR 研究了工艺参数对涂层表面形貌的影响，优化了制备工艺。并通过体外降解实验和电化学测试研究了材料的耐腐蚀性能，探索了材料的腐蚀机理。最后通过细胞实验考察了材料的生物相容性。 实验结果表明，当 TEOS/H2O 的摩尔比为 0.0070，热处理温度为 500 C，提拉次数为 1 3 次时，可获得厚度为 0.43 1.00 m 且表面致密、均匀、无裂纹的 45S5 生物玻璃陶瓷涂层，该涂层由无定形相和少量的六方 Na2Ca2Si3O9相组成。不同厚度的涂层均可提高镁合金基体
4、在浸泡初期的降解性能，降低基体的腐蚀速度， 但在浸泡过程中由于残余应力释放导致涂层开裂和剥落， 引起提拉 1 2 次的试样 （B500 和 2B500） 快速失效， 提拉 3 次的试样 （3B500） 内部应力最低，厚度最高，裂纹形成的过程较为缓慢，在 7 d 的浸泡实验中始终保持最低的基体失重、浸泡液 pH 值变化及腐蚀速度，涂层对基体的保护最为有效。同时，3B500试样提高了基体的自腐蚀电位和抗腐蚀电阻，降低了腐蚀电流密度，提高了材料的耐蚀性能。细胞实验证明 3B500 短期内不具有细胞毒性，且具有比 AZ31 镁合金基体更高的细胞相容性和生物相容性。 通过制备 45S5 生物玻璃陶瓷/羟
5、基磷灰石复合涂层，调控涂层的晶相组成和降解速度，当 45S5 生物玻璃陶瓷溶胶和羟基磷灰石溶胶的体积比是 1:10，热处理温度为 500 C，提拉次数为 3 次时，可以获得均匀致密、无裂纹的复合涂层，复合涂层在浸泡初期可有效保护基体防止被腐蚀，但随着浸泡时间延长，涂层开裂甚至剥落，导致涂层失效，对基体的长期保护作用略低于试样 3B500。电化学测试结果也证明，复合涂层提高了基体的腐蚀电位和抗腐蚀电阻，并降低了基体的腐蚀电流密度，提高了耐蚀性能，但效果略低于试样 3B500。 关键词：关键词： AZ31 镁合金 玻璃陶瓷涂层 溶胶-凝胶 耐蚀性 生物相容性 ABSTRACT Magnesium
6、(Mg) and its alloys have been considered as a promising metallic material for biodegradable bone implants due to their desirable mechanical properties, biocompatibilities, biodegradabilities and bone induction ability. However, the high corrosion rate of magnesium and its alloys in chloride containi
7、ng environment, leaded to the fast loss of mechanical integrity and the release of hydrogen, which limited their biomedical applications. Therefore, it is important to develop magnesium and its alloys with controllable degradabilities. Surface modification with appropriate coatings on Mgbased alloys
8、 is regarded as an effective method to reduce the degradation rate of these Mg alloys. In this work, 45S5 bioactive glassceramic coatings and 45S5 bioactive glassceramic/hydroxyapatite (HA) composite coating have been successfully fabricated on AZ31 magnesium alloys through solgel dipcoating method.
9、 The influence of preparation parameters on the surface morphology of the coating was studied by SEM, XRD and FTIR. The in vitro corrosion properties and mechanism, as well as the biocompatibility of coated AZ31 magnesium alloys were also investigated by immersion test, electrochemical test and cell
10、 culture test. The results showed that homogeneous and crackfree 45S5 bioactive glass-ceramic coatings with the thickness of 0.431.00 m, consisting of amorphous phase and Na2Ca2Si3O9, were successfully fabricated on AZ31 magnesium alloys followed the condition of preparing the precursory sol at TEOS
11、/H2O ratio of 0.0070, dipcoated 13 cycles, and then calcinated at 500 C. All the test coatings can improve the corrosion resistance of the substrate in the initial immersion time; however, cracking and peeling off of the coating resulting from the release of residual stress caused rapid decrease of
12、corrosion resistance for sample B500 and 2B500. Sample 3B500 have the thickest coating thickness and lowest residual stress, displaying the slightest cracking in the immersion test. It is proved that 3B500 performed the lowest mass loss of the substrate, pH variation of SBF solution and crrosion rat
13、e, indicating its superior corrosion resistance. Meanwhile, sample 3B500 increasesd the corrosion potential and impedance of the substrate and decreased the corrosion density of magnesium alloy, improving the anti-corrosion performance. Cell culture testified that sample 3B500 did not have cytotoxic
14、ity in a short term and performed more favorable cytocompatibility and biocompatibility than AZ31 magnesium alloy. To control the phase composition and degradation rate of the coating material, uniform and crack-free 45S5 bioactive glass-ceramic/HA composite coating have been successfully developed
15、followed the condition of preparing the composite sol at the volume radio of the 45S5 bioactive glass-ceramic precursory sol and HA precursory sol of 1:10, dip-coated for 3 cycles and then calcinated at 500 C. The composite coating can effectively protect the substrate from being corroded in the ini
16、tial immersion period; however, it would loss the protectiveness due to the rapid cracking and peeling off in the SBF solution. The results of electrochemical test also showed that the composite coating increased the corrosion potential and impedance of the substrate and decreased the corrosion density of magnesium alloy, improving the corrosion resistance. The results in this work demonstrated that th
