Mg-4.0Zn-2.0Sr-0.4Ca合金复合涂层的耐腐蚀性能

通过环保型阳极氧化工艺及聚合沉积技术在生物材料Mg-4.0Zn-2.0Sr-0.4Ca合金表面逐层制备阳极氧化膜、SiO₂溶胶凝胶、聚多巴胺(PDA)和壳聚糖(CS)复合涂层。采用扫描电镜(SEM)、X射线衍射仪(XRD)观察涂层形貌并确定相组成,采用电化学测试、SBF浸泡试验比较涂层对合金耐蚀性能的影响。结果表明,制备的复合涂层致密完整无缺陷。在SBF溶液中,复合涂层随腐蚀时间的延长逐渐产生裂纹并破碎,产生较小的腐蚀坑,腐蚀在一定程度上被控制在表面,而无涂层Mg-4.0Zn-2.0Sr-0.4Ca合金在SBF溶液中的腐蚀以点蚀和局部腐蚀为主,且腐蚀程度随腐蚀时间的延长而加剧。复合涂层在SBF溶液中的腐蚀电流密度、腐蚀电位和平均腐蚀速率分别为5.7039 μA/cm²、-1.4203 V(vs SCE)和0.163 g/(m²·h),均优于无涂层镁合金,且平均腐蚀速率降幅达50%以上,说明制备的复合涂层可显著提高Mg-4.0Zn-2.0Sr-0.4Ca合金的耐腐蚀性能。

Corrosion resistance of Mg-4.0Zn-2.0Sr-0.4Ca alloy composite coating

Through environmentally friendly anodizing process and polymer deposition technology, a composite coating of anodic oxide film, SiO₂ sol-gel, polydopamine (PDA) and chitosan (CS) were prepared layer by layer on the surface of Mg-4.0Zn-2.0Sr-0.4Ca alloy. The morphology of the coating was observed by using scanning electron microscope (SEM), the phase composition was determined by using X-ray diffractometer (XRD), and the corrosion resistance was tested by means of electrochemical testing and in SBF immersion. The results show that the composite coating is compact and complete without any defects. In the SBF solution, the composite coating gradually cracks and breaks with the prolongation of corrosion time, resulting in smaller corrosion pits, which shows the corrosion is controlled on the surface at a certain degree. However, the corrosion of uncoated Mg-4.0Zn-2.0Sr-0.4Ca alloy is mainly corrosion pits and local corrosion, and the corrosion intensifies with the prolongation of corrosion time. In addition, the corrosion current density, corrosion potential and average corrosion rate of the composite coating in SBF solution are 5.7039 μA/cm², -1.4203 V(vs SCE) and 0.163 g/(m²·h), which is better than that of the uncoated Mg-4.0Zn-2.0Sr-0.4Ca alloy, especially the average corrosion rate drops by more than 50%, which indicates that the prepared composite coating can significantly improve the corrosion resistance of the Mg-4.0Zn-2.0Sr-0.4Ca alloy.