超疏水镁合金表面的构建及耐腐蚀性能研究

发布时间：2018-03-09 16:44

本文选题：镁合金　切入点：超疏水　出处：《兰州交通大学》2016年硕士论文　论文类型：学位论文

【摘要】：镁及其合金具有比重轻,比刚度和比强度高,切削加工性能、导热性能以及铸造性能良好等一系列的优点,因此,镁及镁合金在交通运输、电子设备、汽车行业以及航空航天等领域均得到了广泛的应用。但是,因为镁及其合金的耐腐蚀性能比较差,这就很大程度上影响了它的大规模使用。研究表明通过在材料表面构建强疏水层,可以提高相关材料的耐腐蚀性能和表面自清洁性能。基于此,本研究依据镁的物理化学性质,采用了两种过程简单、成本低廉的制备方法构建了超疏水镁合金表面。与此同时,研究了镁合金表面的耐腐蚀性能及自清洁性能,主要研究内容和结论如下:(1)通过盐酸刻蚀、氨水浸泡和疏水长链接枝的方法,成功构建得到接触角达154.1°、滚动角为6°的超疏水镁合金表面。利用接触角测试、扫描电镜观察、红外光谱分析、防黏附和电化学实验等分别对超疏水镁合金表面的润湿性能、表面微结构和化学组成、防黏附行为和耐腐蚀性能进行了考察。研究结果表明:盐酸刻蚀和氨水浸泡使得镁合金表面产生了微/纳复合结构,而硬脂酸修饰使疏水烃基长链通过化学键接枝到具有微/纳复合结构的镁合金表面。正是由于其特殊的表面微结构和化学组成,使得超疏水镁合金表现出了良好的防黏附行为和耐腐蚀性能。(2)通过水热法在镁合金表面成功构建了一薄层超疏水膜,分别探讨了反应温度、反应时间、乙醇与水的体积比以及STA醇溶液浓度对镁合金接触角的影响。最后得出了最理想的反应条件是:水热法的反应温度为80 oC,在烘箱中的保温时间为10 h,乙醇与水的体积比为1:1.4,硬脂酸乙醇溶液浓度为80 mmol/L。在最优条件下制备得到的超疏水镁合金的表面接触角达到153.8°,滚动角为6°。利用电镜照片观察可知,通过水热法处理之后,镁合金表面构建出了与基底牢固结合的原位生长的膜层,而且这些膜层由片状的结构错落交替而成。(3)采用电化学测试和盐水浸泡分别对两种方法制备的超疏水镁合金的耐腐蚀性能进行研究。由电化学测试得到的Tafel曲线结果表明:超疏水促使镁合金片的腐蚀电流密度数值变小而腐蚀电位数值增大。这表明镁合金表面的超疏水膜层提高了材料的耐腐蚀性能。另外,我们将两种方法所制备的超疏水状态的镁合金片和空白试样放入盐水溶液中浸泡,通过接触角测试、EDS和XRD分析、SEM观察对不同浸泡时间后试样表面接触角值、表面组成、相结构和形貌变化进行分析可知,相对于空白试样,超疏水试样有比较好的耐腐蚀性能。(4)超疏水镁合金表面上的水珠在其表面滚动的时候,可以带走铺在表面的碳粉、烟灰、粉笔灰等污染物颗粒,这表明超疏水镁合金表面也具有优异的自清洁性能。
[Abstract]:Magnesium and its alloys have a series of advantages such as light specific gravity, high specific stiffness and specific strength, cutting and processing properties, thermal conductivity and good casting properties. Therefore, magnesium and magnesium alloys are used in transportation, electronic equipment, etc. The automotive industry, aerospace and other fields have been widely used. However, because of the poor corrosion resistance of magnesium and its alloys, The results show that the corrosion resistance and self-cleaning properties of the related materials can be improved by constructing a strong hydrophobic layer on the surface of the material. Based on this, this study is based on the physical and chemical properties of magnesium. The surface of superhydrophobic magnesium alloy was constructed by two simple and low cost preparation methods. At the same time, the corrosion resistance and self-cleaning property of magnesium alloy surface were studied. The main contents and conclusions are as follows: 1) etching by hydrochloric acid. The surface of superhydrophobic magnesium alloy with contact angle of 154.1 掳and rolling angle of 6 掳was successfully constructed by soaking in ammonia water and hydrophobic long linking branch. Contact angle test, scanning electron microscope observation and infrared spectroscopy were used to analyze the surface of superhydrophobic magnesium alloy. The wettability, microstructure and chemical composition of superhydrophobic magnesium alloy surface, such as adhesion resistance and electrochemical experiments, The adhesion behavior and corrosion resistance of magnesium alloy were investigated. The results showed that the microstructures / nanocomposites were formed on the surface of magnesium alloy by hydrochloric acid etching and ammonia immersion. The modification of stearic acid makes the hydrophobic alkyl long chain grafted to the surface of magnesium alloy with micro / nano composite structure by chemical bonding. It is precisely because of its special surface microstructure and chemical composition, The superhydrophobic magnesium alloy exhibits good adhesion behavior and corrosion resistance. (2) A thin layer of superhydrophobic film was successfully constructed on the surface of superhydrophobic magnesium alloy by hydrothermal method. The reaction temperature and reaction time were discussed respectively. The effect of the volume ratio of ethanol to water and the concentration of STA alcohol solution on the contact angle of magnesium alloy was obtained. The optimal reaction conditions were obtained as follows: the reaction temperature of hydrothermal method was 80 OC, the holding time in oven was 10 h, and the temperature of ethanol and water was 10 h. The volume ratio is 1: 1.4 and the concentration of stearic acid ethanol solution is 80 mmol / L. the surface contact angle and rolling angle of the superhydrophobic magnesium alloy prepared under the optimum conditions are 153.8 掳and 6 掳respectively. After hydrothermal treatment, the surface of magnesium alloy was formed by in situ growth, which was firmly bonded to the substrate. The corrosion resistance of superhydrophobic magnesium alloy prepared by electrochemical test and brine immersion was studied by electrochemical test and brine immersion respectively. The Tafel curve obtained from electrochemical test was obtained from the electrochemical test. The results show that superhydrophobicity can decrease the corrosion current density of magnesium alloy sheet and increase the corrosion potential value, which indicates that the superhydrophobic coating on magnesium alloy surface improves the corrosion resistance of magnesium alloy. The superhydrophobic magnesium alloy sheets and blank samples prepared by the two methods were immersed in brine solution. The surface contact angle and composition of the samples were observed by EDS and XRD analysis. The analysis of phase structure and morphology shows that the superhydrophobic sample has better corrosion resistance than the blank sample) when the water droplets on the surface of superhydrophobic magnesium alloy roll on its surface, it can take away the carbon powder and soot spread on the surface. The superhydrophobic magnesium alloy surface also has excellent self-cleaning properties, such as chalk ash and other contaminant particles.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG178

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