Mg-2Zn-1Mn-0.5Ca合金表面微弧氧化涂层制备及耐蚀性研究

发布时间：2018-03-06 12:39

本文选题：Mg-2Zn-1Mn-0.5Ca合金　切入点：微弧氧化　出处：《哈尔滨理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：镁及镁合金具有良好的生物相容性，因此在生物医学等领域具有广阔的应用前景，但由于镁在元素周期表中排在IIA族，比较活泼，在使用过程中极易腐蚀，这极大地限制了镁合金的应用。为提高镁合金的耐蚀性，进一步扩展其应用范围，本文以Mg-2Zn-1Mn-0.5Ca生物镁合金为研究对象，通过微弧氧化方法在合金表面生长一种耐腐蚀的生物涂层，研究并优化了Mg-2Zn-1Mn-0.5Ca合金的微弧氧化工艺及参数，并进一步揭示了工艺参数对涂层耐腐蚀性的影响规律。选取NaOH、Na2SiO3、KF三种成分为基础电解液，在较高的电源频率1000Hz及15%的占空比下，通过改变氧化电压、氧化时间、添加剂含量等工艺参数来制备不同的氧化涂层。利用SEM、XRD等实验手段揭示了不同工艺参数对涂层的厚度、表面形貌及物相组成的影响规律。结果表明，随着氧化电压的升高，涂层厚度先增大后减小，涂层表面微孔尺寸逐渐减小，但微孔密度持续增大，表面粗糙度减小，当电压到达一定值时，易造成涂层击穿。随着氧化时间的增加，涂层厚度持续增加，当达到平衡状态时，涂层厚度不再增加。添加剂的加入使得涂层厚度显著增加，并随着其含量的增加，涂层表面更加致密平滑。利用点滴实验、模拟体液浸泡、极化曲线等手段揭示不同工艺参数对涂层耐蚀性的影响规律。结果表明随着氧化电压的增加，涂层的耐蚀性先增强后减弱；氧化时间对涂层的耐蚀性影响主要是通过改变涂层厚度实现的；添加剂的加入使得腐蚀电位增加，涂层表面耐蚀性增强。当采用的微弧氧化工艺参数为氧化电压350V、氧化时间10min，添加苯甲酸钠量2g/L时，制备出的Mg-2Zn-1Mn-0.5Ca生物镁合金表面涂层表面平滑致密，无微观缺陷，在模拟体液中浸泡四周后表面涂层完好，，金相显微镜下观察涂层降解均匀，未有基体露出，耐蚀性良好。
[Abstract]:Magnesium and magnesium alloys have good biocompatibility, so they have a wide application prospect in biomedicine and other fields. However, magnesium is easily corroded in the process of application because of its IIA family in the periodic table. In order to improve the corrosion resistance of magnesium alloys and further expand their application scope, a kind of anticorrosive biologic coating was grown on the surface of Mg-2Zn-1Mn-0.5Ca biological magnesium alloy by micro-arc oxidation method. The microarc oxidation process and parameters of Mg-2Zn-1Mn-0.5Ca alloy were studied and optimized, and the effect of process parameters on corrosion resistance of Mg-2Zn-1Mn-0.5Ca alloy was revealed. Three components of NaOHN Na2SiO3KF were selected as the base electrolyte, and the oxidation voltage and time were changed at higher power frequency 1000Hz and 15% duty cycle. The effects of different process parameters on the thickness, surface morphology and phase composition of the coatings were revealed by means of SEM XRD and other technological parameters. The results showed that the oxidation voltage increased with the increase of oxidation voltage. The coating thickness first increases and then decreases, and the micropore size decreases gradually, but the micropore density increases continuously and the surface roughness decreases. When the voltage reaches a certain value, the coating breakdown is easy to be caused, and with the increase of oxidation time, The thickness of the coating increases continuously, and when the coating reaches the equilibrium state, the thickness of the coating does not increase. The addition of additives makes the coating thickness increase significantly, and with the increase of its content, the coating surface becomes denser and smoother. The effects of different process parameters on the corrosion resistance of the coatings were revealed by drip experiments, simulated body fluid immersion and polarization curves. The results showed that the corrosion resistance of the coatings increased first and then weakened with the increase of oxidation voltage. The effect of oxidation time on the corrosion resistance of the coating is mainly achieved by changing the thickness of the coating, and the corrosion potential increases and the corrosion resistance of the coating surface increases with the addition of additives. When the process parameters of micro-arc oxidation are 350V oxidation voltage, 10min oxidation time and 2g / L sodium benzoate added, the surface of the surface coating of Mg-2Zn-1Mn-0.5Ca biological magnesium alloy is smooth and compact without microcosmic defects. After immersion in simulated body fluid for four weeks, the surface coating was intact, and the coating was degraded evenly under metallographic microscope, no substrate was exposed, and the corrosion resistance was good.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG174.4

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