【作者】 东青；

【导师】 陈传忠；

【作者基本信息】 山东大学 ， 材料学， 2007， 硕士

【摘要】 镁及其合金在硬组织替代领域一直受到研究人员的关注。相对于目前常用的钛合金材料，这类材料在密度，强度和弹性模量等方面更接近于人体骨骼，而且镁作为人体中第四丰富的阳离子，在人体的新陈代谢过程中具有重要作用。镁基植入体在体内环境中经腐蚀后可以形成易溶且无毒的氧化物，是理想的轻量可降解硬组织修复材料，具有生物相容性而且可能具备生物活性。但由于该材料在pH值在7.4-7.6之间的溶液以及较高氯离子的生理系统中，其腐蚀速率过快，以致在组织完全愈合之前就会失去足够的力学性能，限制了这类材料的使用。微弧氧化是近年发展起来的一种先进的有色金属表面陶瓷涂层制备技术，利用该技术制备的陶瓷涂层不仅性能优异，而且其电解液中不含对人体有害的金属离子和化学成分，保证了涂层使用的安全性。因此，针对镁合金材料，研究在人体环境中具有较好耐蚀性以及生物活性的微弧氧化涂层制备技术，具有重要意义。本文分别采用磷酸盐和硅酸盐电解液对Al，Mg，Ti及其合金进行微弧氧化，综合运用XRD，SEM，EDS和TEM对微弧氧化涂层的成分、相组成以及结构特点进行分析。在上述工作基础上选用ZK61镁合金为基体，以硅酸盐为电解液，制备微弧氧化涂层，并对涂层的耐蚀性和生物活性进行了评价。XRD分析表明微弧氧化涂层主要由基体元素的氧化物构成，如γ-Al₂O₃，MgO，金红石及锐钛矿型TiO₂。TEM分析表明微弧氧化涂层中含有大量非晶组织，而且其数量明显多于晶态氧化物。另外，对于铝合金上的氧化涂层，发现初生的结晶态氧化物与母相基体之间存在特定的晶体学位向关系。TEM和EDS均表明，基体中的合金元素及电解液均可对涂层成分及相组成产生影响。Si元素极易进入涂层并形成化合物，在ZL109铝合金及AZ91镁合金表面的微弧氧化涂层中均发现少量的SiO₂，在ZK61镁合金表面的涂层中则有大量的Mg₂SiO₄及少量的MgSiO₃，Mg₂（Si₂O₆）和SiO₂。SEM表明微弧氧化涂层表面为多孔状形貌，孔洞直径在1-5μm之间。基体材料属性及工艺参数对微孔的大小及分布有显著影响。EDS表明微弧氧化涂层内部较为致密，涂层均匀连续，与基体之间为冶金结合，在成分上存在宽度为数微米的过渡区。对涂层的硬度进行测试，结果显示微弧氧化涂层均具有较高的硬度。对ZK61镁合金进行了模拟体液（SBF）浸泡试验，结果表明微弧氧化涂层可以显著提高ZK61合金在SBF中的耐蚀性。浸泡4周后，涂层表面有富含Ca，P元素的磷灰石层沉积，表明该涂层具有良好的生物活性。更多还原

【Abstract】 Magnesium and its alloys continue to be attached importance as orthopedic biomaterials. Compare with titanium alloys that have been widely used now, the properties of magnesium, such as density, strength and elastic modulus, are closer to that of natural bones. As the fourth most abundant cation in the human body, magnesium plays an essential role in the metabolism of the body. The formation of a soluble, non-toxic oxide can be caused by the in vivo corrosion of the magnesium-based implant. Therefore, magnesium-based materials have a potential as lightweight, degradable, biologically compatible and possibly biologically active orthopedic implants. The major drawback of magnesium is its low corrosion resistance, especially when the physiological pH in the range of 7.4-7.6 and in high chloride environment. The implants will lose mechanical integrity before the tissue has sufficiently healed, which limit the use of these materials.Micro-arc oxidation （MAO） is a novel surface treatment technology which can prepare ceramic coatings on nonferrous metals. The MAO coating has excellent properties and the applied electrolyte has no heavy metal ions and chemical composition that are harmful to the human body, so the security can be guaranteed when the coating was used as biomaterials. It is promising to prepare MAO coatings on magnesium-based materials that have good corrosion resistance and bioactivity.In this paper, MAO coatings are prepared on the surface of Al, Mg, Ti and their alloys using phosphate or silicate salt electrolyte. The composition, phases and structure of the coatings are analyzed by XRD, SEM and TEM. On the basis of the above work, MAO coatings are prepared on the ZK61 alloy using silicate salt electrolyte. The corrosion resistance and bioactivity of the coatings are evaluated.XRD analysis shows that the MAO coatings are mainly composed of substrate element oxide, such asγ-Al₂O₃, MgO, rutile and anatase TiO₂. TEM shows that there is a lot of amorphous structure in the coating, whose amount is more than crystalline oxide. In addition, it is found that the initial crystalline Al₂O₃ has a special crystal orientation with the aluminum substrate. TEM and EDS results show that the elements both in the substrate and the electrolyte have effects on the composition and phase of the MAO coating. Silicon can easily be absorbed into the coating and forms compounds. Few amount of SiO₂ are found in the MAO coatings on the ZL109 and AZ91 alloys. Large amount of Mg₂SiO₄ and few MgSiO₃, Mg₂（Si₂O₆） and SiO₂ are found in the MAO coatings on the ZK61 alloy. SEM shows that all the coatings are micro-porous with 1-5μm pores. The dimension and distribution of the pores depend on the nature of the substrate materials and the technical parameters. EDS shows that the inner of the MAO coating is dense and homogeneous, and the combination with the substrate is excellent. A transitional zone with a thickness of several microns is observed on the interface between the coating and substrate. The hardness of the coatings is tested. The result indicates that MAO coatings have high hardness. SBF tests show that the corrosion resistance in SBF of the ZK61 alloy can be greatly enhanced. Apatite layers containing Ca and P are deposited on the MAO coatings after the samples are immersed in SBF for 4 weeks, which indicates that the MAO coating has excellent bioactivity.更多还原