Al-Mn-Zr三元合金膜的离子液体电沉积制备及其腐蚀电化学性能研究

发布时间：2018-06-15 00:31

本文选题：离子液体 + 电沉积　；参考：《浙江大学》2017年硕士论文

【摘要】：铝及铝合金具有优良的物理化学性能,尤其是铝锰合金,不仅具有良好的成形性能及装饰作用,而且强度高,耐腐蚀性好,而Al-Mn合金金属玻璃结构的发现,更是引起了国内外学者的极大兴趣。然而,低锰含量的Al-Mn合金因为晶粒粗大、晶粒间有空隙,不能对基体起到明显的防护作用。离子液体因为具有熔点低、无蒸气压、稳定性好及电化学窗口宽等优点而在电沉积领域备受关注。为了提高低锰含量的Al-Mn合金的耐腐蚀性能,本论文采用离子液体电沉积技术,通过在AlCl3- MnCl2-EMIC(氯化-1-乙基-3甲基咪唑)离子液体中添加ZrCl4,成功在低碳钢基体表面制备了Al-Mn-Zr三元合金镀层,并采用线性扫描伏安法、计时电位法分析了电沉积过程中的电化学行为；采用SEM、XRD、EDS、极化曲线、电化学阻抗谱等手段分析了镀层形貌、结构与防腐蚀性能。所取得的主要结果如下：(1)对电沉积过程中的电化学行为的研究结果表明：ZrCl4在电解液中的添加增大了合金共沉积的过电位,促进了电结晶过程中的形核过程,从而可以细化晶粒。(2)研究了不同Zr含量对Al-Mn-Zr三元合金镀层形貌、结构的影响,结果表明：当镀层中Zr含量较少时,镀层晶粒相比Al-Mn合金镀层晶粒明显细化,但仍为微米级晶粒,此时Zr、Mn以饱和固溶体形式存在；当ZrCl4在电解液中的添加量增加至5 mmol·L-1时,镀层更加致密,构成沉积颗粒的微晶为纳米级(50nm),此时镀层为晶态与非晶态的混合结构；但是当ZrCl4在电解液中的添加量为10 mmol·L-1时,镀层表面会发生沉积颗粒团聚现象,导致镀层疏松。EDS、 XRD及Mapping谱图分析进一步表明,Al、Mn、Zr三种金属元素是以共沉积的方式形成Al-Mn-Zr合金的,而且三种金属元素在镀层中分布均匀。(3)对镀层的防腐蚀性能研究结果表明：Al-Mn-Zr三元合金的耐腐蚀性能比Al-Mn合金好,证明Zr的添加可以改善Al-Mn合金的防腐蚀性能。当ZrCl4在电解液中添加量为5 mmol·L-1时,所制备的Al-Mn-Zr合金膜显示了较佳的耐腐蚀性能。
[Abstract]:Aluminum and aluminum alloys have excellent physical and chemical properties, especially aluminum-manganese alloys, which not only have good formability and decoration, but also have high strength and good corrosion resistance. It has aroused the great interest of scholars both at home and abroad. However, the Al-Mn alloy with low mn content can not protect the matrix obviously because of the coarse grain size and the void between the grains. Ionic liquids have attracted much attention in electrodeposition due to their advantages of low melting point, no vapor pressure, good stability and wide electrochemical window. In order to improve the corrosion resistance of Al-Mn alloy with low manganese content, the ionic liquid electrodeposition technique was used in this paper. Al-Mn-Zr ternary alloy coating was successfully prepared on the surface of low carbon steel by adding ZrCl _ 4 into ALCL _ 3-MnCl _ 2-EMIC (chlorinated -1-ethyl-3 methyl imidazole) ionic liquid. The electrochemical behavior of Al-Mn-Zr alloy coating during electrodeposition was analyzed by linear scanning voltammetry and chronopotentiometry. The morphology, structure and corrosion resistance of the coating were analyzed by means of SEMX XRDX EDS, polarization curve and electrochemical impedance spectroscopy (EIS). The main results obtained are as follows: (1) the results of the study on the electrochemical behavior during electrodeposition show that the addition of 1: ZrCl4 to the electrolyte increases the overpotential of the co-deposition of the alloy and promotes the nucleation process in the electrocrystallization process. The effect of Zr content on the morphology and structure of Al-Mn-Zr ternary alloy coating was studied. The results showed that the grain size of Al-Mn-Zr alloy coating was smaller than that of Al-Mn alloy coating when Zr content was low, but it was still micron grain. When the amount of ZrCl4 in electrolyte increases to 5 mmol L-1, the coating becomes denser, and the microcrystal of the deposited particles is nanocrystalline (Nano), and the coating is a mixed structure of crystalline and amorphous state. However, when the amount of ZrCl4 added in electrolyte is 10 mmol L-1, the agglomeration of deposited particles will occur on the surface of the coating, which leads to the formation of Al-Mn-Zr alloy by co-deposition of three metal elements, I. e. EDS, XRD and Mapping. The results show that the corrosion resistance of Al-Mn-Zr ternary alloy is better than that of Al-Mn alloy, which proves that the addition of Zr can improve the corrosion resistance of Al-Mn alloy. When ZrCl _ 4 was added into the electrolyte for 5 mmol L ~ (-1), the Al-Mn-Zr alloy film showed good corrosion resistance.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.4

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