AZ31镁合金表面抗腐蚀复合膜层制备及表征
发布时间：2018-10-15 17:32
【摘要】：镁合金是一种很有应用前景的可降解生物医用金属材料。然而镁合金在人体环境中腐蚀速率过快，限制了其临床应用。本文对AZ31镁合金进行了微弧氧化处理，采用溶胶-凝胶法在合金表面制备了Ca-P层和MgO/Ca-P复合层，采用涂覆法在合金表面制备了PLA和MgO/PLA复合层。利用扫描电子显微镜（SEM）、能谱（EDS）和X-射线衍射分析（XRD）等方法对表层进行形貌观察、成分分析与相结构分析，采用拉伸实验法对涂层与基体之间的结合强度进行评价，通过在模拟体液中的浸泡试验、动电位极化测量和电化学阻抗谱分析等电化学方法评价了表面处理对AZ31合金抗腐蚀性能的影响。 采用Ca（NO3）2·4H2O和P2O5乙醇溶胶溶液，可在AZ31镁合金和微弧氧化后的表面制备一层分布均匀的钙磷层。经300℃烧结时，膜层主要由Ca2P2O7相组成；经400℃烧结时，组成相Ca2P2O7、Ca3（PO4）2和Ca10（PO4）6（OH）2相；经500℃烧结时，组成相全部为Ca10（PO4）6（OH）2相。在300℃到500℃之间烧结，钙磷膜层与基体的结合强度不低于22MPa。随着烧结温度的升高，膜层的结合强度及膜层中裂纹所占面积百分比增大。相比于同温度下在镁合金基体表面制备的Ca-P层，MgO/Ca-P复合膜层的结合强度更高（不低于33MPa），复合膜层表面裂纹面积所占百分比更小。原因是MgO中间层减小了Ca-P层与镁合金基体两相间热膨胀系数的差异，降低了烧结过程中膜层产生的残余内应力。溶胶凝胶法制备的Ca-P层及MgO/Ca-P复合层能明显改善AZ31镁合金的抗腐蚀性能，Ca-P层对抗蚀性的改善作用随着烧结温度的升高而降低。MgO/Ca-P复合层对抗腐蚀性能的改善作用要明显优于单一Ca-P层，其原因是MgO本身具有良好的耐蚀性能，同时由于其与Ca-P化合物的热膨胀系数相近，又具有粗糙的表面结构，使得Ca-P层与基体的结合强度更高。 将PLA溶解在三氯甲烷中制备的胶体涂覆在镁合金表面及微弧氧化后的镁合金表面，，可以在合金表面获得均匀、致密、无裂纹的PLA膜层。PLA与AZ31基体之间的结合强度不低于35MPa，PLA与MgO之间的结合强度均不低于40MPa。PLA可以与多孔MgO层之间形成机械锁和，导致PLA与MgO之间的结合强度更高。微弧氧化层经PLA封孔后能明显改善AZ31基体的耐蚀性，其中浓度为10%的聚乳酸涂层对耐蚀性的改善效果要优于浓度为5%的聚乳酸涂层，MgO/PLA复合层对AZ31镁合金抗蚀性的改善作用要明显优于PLA单一层。 相比于AZ31镁合金表面制备的MgO/Ca-P复合层，MgO/PLA复合表面改性后的AZ31镁合金的抗腐蚀性能更好。
[Abstract]:Magnesium alloy is a promising biodegradable biomedical metal material. However, magnesium alloy corrosion rate in human environment is too fast, limiting its clinical application. In this paper, AZ31 magnesium alloy was treated by micro-arc oxidation, Ca-P and MgO/Ca-P composite layers were prepared by sol-gel method, and PLA and MgO/PLA composite layers were prepared on alloy surface by coating method. The surface morphology, composition and phase structure were observed by scanning electron microscope (SEM) (SEM), (EDS) and X-ray diffraction (XRD), and the bonding strength between coating and substrate was evaluated by tensile test. The effect of surface treatment on corrosion resistance of AZ31 alloy was evaluated by immersion test in simulated body fluid, potentiodynamic polarization measurement and electrochemical impedance spectrum analysis. Using Ca (NO3) 2 4H2O and P2O5 ethanol sol solution, a uniform layer of calcium and phosphorus was prepared on the surface of AZ31 magnesium alloy and micro-arc oxidation. When sintered at 300 鈩
本文编号：2273281
[Abstract]:Magnesium alloy is a promising biodegradable biomedical metal material. However, magnesium alloy corrosion rate in human environment is too fast, limiting its clinical application. In this paper, AZ31 magnesium alloy was treated by micro-arc oxidation, Ca-P and MgO/Ca-P composite layers were prepared by sol-gel method, and PLA and MgO/PLA composite layers were prepared on alloy surface by coating method. The surface morphology, composition and phase structure were observed by scanning electron microscope (SEM) (SEM), (EDS) and X-ray diffraction (XRD), and the bonding strength between coating and substrate was evaluated by tensile test. The effect of surface treatment on corrosion resistance of AZ31 alloy was evaluated by immersion test in simulated body fluid, potentiodynamic polarization measurement and electrochemical impedance spectrum analysis. Using Ca (NO3) 2 4H2O and P2O5 ethanol sol solution, a uniform layer of calcium and phosphorus was prepared on the surface of AZ31 magnesium alloy and micro-arc oxidation. When sintered at 300 鈩
本文编号：2273281
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