离子液体电沉积铝微观形貌研究

发布时间：2018-05-12 03:35

本文选题：离子液体 + 电沉积　；参考：《沈阳师范大学》2015年硕士论文

【摘要】：铝是国民经济中重要的基础金属原料,目前电解铝行业存在着生产温度高、能耗大和排放有污染等问题。离子液体作为一种新型的低温电解质,在金属电沉积领域有着广阔的应用前景。但以纯的离子液体为电解质无法兼顾均镀能力和沉积层的平整性,沉积层表面容易形成枝晶。利用脉冲电沉积作为离子液体电沉积的新方法也缺少系统性的研究。甲基三乙基氯化铵(N2221)/Al C l3、1-乙酸乙酯基-3-甲基-咪唑/Al C l3离子液体作为电解质,还没有详细报道。本文从上述背景出发,系统研究添加剂、电沉积实验方法、电解质体系对离子液体电沉积铝微观形貌的影响,论文主要研究内容如下:1.以[Emim]C l/Al C l3(33.3/66.7mol%)离子液体为电解质,选取了丙酮、乙酰胺、乙酸、乙酸甲酯、氨基甲酸甲酯五种含有羰基官能团的有机物作为离子液体电沉积铝的添加剂,考察其对电沉积铝的影响。通过CV、SEM、XRD、UV-Vis、NMR等分析,进一步系统研究了添加剂的浓度、电流密度对Al沉积层形貌、晶面取向及沉积机理的影响。结果表明:氨基甲酸甲酯是一种性能优异、无毒且价廉易得的整平添加剂,45mmol/L氨基甲酸甲酯的加入明显改善Al产品的光亮度,得到细致均匀且镜面光亮的Al沉积层。氨基甲酸甲酯为添加剂时,在电解液体系中没有形成新的金属络合离子,不影响电解液中活性铝离子结构;其羰基碳原子为正电中心在阴极表面吸附,对Al的电沉积过程产生抑制进而获得整平和光亮效果。同时,选择一系列含有S=O键的有机物,作为离子液体电沉积铝的添加剂,对比分析其与吸附类添加剂的不同机理。研究发现:二甲基砜作为离子液体电沉积铝的添加剂时,二甲基砜与Al Cl3络合形成新的Al(DMSO2)33+金属络合离子。这种络合离子没有使Al沉积层表面变得平滑光亮,反而使沉积层表面更加粗糙,更容易形成枝晶。2.尽管离子液体电沉积铝使用脉冲电沉积的方法具有着潜在优势,但是并没有文献报道脉冲极化过程的本质,系统的研究电沉积铝过程及形貌变化。所以本文以恒电流法、恒电位法、脉冲电流法、脉冲电位法,分析不同时间、电流密度、电压、电荷量下电沉积铝过程及形貌,尝试找出其沉积形貌规律,及其沉积过程机理。3.测定并讨论了N2221/Al C l3、1-乙酸乙酯基-3-甲基-咪唑/Al Cl3等氯铝酸离子液体的电化学性能,通过循环伏安、SEM、XRD等方法重点研究了不同温度、电流密度和不同电压下铝在阴极的沉积过程,同时考察了铝的形貌、晶体结构等宏观性质,筛选出最佳的电沉积铝实验参数,并系统分析其原理。
[Abstract]:Aluminum is an important basic metal material in the national economy. At present, the electrolytic aluminum industry has many problems, such as high production temperature, high energy consumption and pollution. As a new low temperature electrolyte, ionic liquid has a broad application prospect in the field of metal electrodeposition. However, using pure ionic liquid as electrolyte can not take into account the uniform plating ability and the smoothness of the deposit layer, and the dendrite is easy to be formed on the surface of the deposit layer. The use of pulse electrodeposition as a new method of ionic liquid electrodeposition is also lack of systematic research. The ionic liquid of methyl triethylammonium chloride N 2221 / Al Cl 3H 1acetate ethyl ester group -3-methyl-imidazole group as electrolyte has not been reported in detail. Based on the above background, the effects of additives, electrodeposition methods and electrolyte system on the micromorphology of aluminum electrodeposition in ionic liquids are studied systematically. The main contents of this paper are as follows: 1. Using [Emim] C l/Al C3 / 66.7 mol liquid as electrolyte, five organic compounds containing carbonyl functional groups, acetone, acetamide, methyl acetate and methyl carbamate, were selected as additives for electrodeposition of aluminum in ionic liquids. Its effect on electrodeposition of aluminum was investigated. The effects of additive concentration and current density on the morphology, crystal orientation and deposition mechanism of Al deposits were further studied by UV-VisNMR analysis. The results show that methyl carbamate is a kind of excellent leveling additive with excellent performance, nontoxic and cheap, and the addition of methyl carbamate 45 mmol / L can obviously improve the luminance of Al products and obtain a fine and uniform Al deposit layer with bright mirror surface. When methyl carbamate is used as additive, no new metal complex ion is formed in electrolyte system, which does not affect the structure of active aluminum ion in electrolyte, and its carbonyl carbon atom is adsorbed on cathode surface at the center of positive charge. The electrodeposition process of Al was inhibited and the leveling and luminous effect was obtained. At the same time, a series of organic compounds containing Schio bond were selected as additives for electrodeposition of aluminum in ionic liquids, and their different mechanisms were compared with those of adsorbed additives. It is found that when dimethyl sulfone is used as additive for electrodeposition of aluminum in ionic liquids, dimethyl sulfone complexes with Al Cl3 to form new Al(DMSO2)33 metal complex ions. This complex ion does not make the surface of Al deposit smooth and bright, on the contrary, it makes the surface of the deposit more rough and easy to form dendrite. 2. Although the method of pulse electrodeposition of aluminum by ionic liquid has potential advantages, there is no report on the nature of pulse polarization process, and the process and morphology of aluminum electrodeposition are systematically studied. In this paper, the electrodeposition process and morphology of aluminum under different time, current density, voltage and charge are analyzed by means of constant current method, constant potential method, pulse current method and pulse potential method. The electrochemical properties of ionic liquids such as N2221/Al Cl _ 3C _ 3N _ 1-acetate _ 3-methyl-imidazole / Al _ Cl3 were measured and discussed. The deposition process of aluminum at different temperature, current density and voltage was studied by cyclic voltammetry. At the same time, the morphology, crystal structure and other macroscopic properties of aluminum were investigated, the optimum experimental parameters of electrodeposition aluminum were selected, and its principle was systematically analyzed.
【学位授予单位】：沈阳师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ153

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