离子液体电沉积锌镍及锌镁合金的研究

发布时间：2018-01-28 10:52

本文关键词： 离子液体锌镍合金锌镁合金电沉积循环伏安曲线　出处：《昆明理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：锌合金作为一种新型的防护镀层一直受到广泛的关注,由于其具有良好的成型性、可焊性、上漆性,被广泛的用作航空航天、汽车、电子等工业中钢制品的防护层。传统的锌镍合金生产方法有熔融法和电镀两种。熔融法生产的锌镍合金分散程度差,合金中镍含量低,不符合现在的防腐要求。电镀主要有酸性和碱性水溶液两种,由于其对环境不友好,使得其在工业上的应用受到影响。锌镁合金生产的方法有热镀、真空镀、熔盐电镀、气相沉积等几种。现在研究锌镁合金镀层的焦点主要在硫酸水溶液中,镀层中的镁含量较低。因此,寻求一种低成本、工艺简单、绿色环保的锌合金制备方法具有重要的意义。基于上述情况我们采用EG-ZnCl2离子液体和尿素-氯化锌-氯化镍低共融盐体系作为电解质,进行了锌镁合金和锌镍合金电沉积的研究。两种电解质不仅具有绿色环保的优点,而且具有成本低廉、体系简单、空气不敏感等特点,可以在裸露的空气中操作,符合绿色生产工艺可持续发展的要求。测定了ZnCl2、NiCl2、Urea三者不同含量时形成离子液体的电导率；采用计时电流法和循环伏安曲线等手段研究了锌镍合金的电化学性质；采用响应曲面法对沉积条件进行了优化；采用EDS和XRD对镀层进行了分析。其结果表明：ZnCl2:NiCl2:Urea的摩尔比为：2.9：1.5：16.7时体系的电导率最好,电导率与温度的关系符合Arrhenius公式,通过拟合得到该离子液体溶液的活化能为30.733kJ/mol; Zn-Ni的电结晶经历了形核过程,电结晶过程按瞬时形核进行；在不扫速下的Urea-ZnCl2-NiCl2离子液体的循环伏安曲线中,随着扫速的增大,还原峰值电流大致呈增加的趋势；沉积温度对镀层中锌的质量分数的影响较小,EG加入量和沉积电位的交互作用较为显著,优化得沉积条件为EG的质量分数为28.4%、沉积电位为2.1V、沉积温度为358K；镀层为球形颗粒组成,平均粒径为2.5 μ m,无裂缝,无空隙,为锌镍合金的固溶体,Zn的质量分数为33%。加入EG后镀层的颗粒平均直径小于1μm,镀层的厚度小于20μm,镀层与基体的结合程度较好,平整,镀层中Zn元素和Ni元素的分布均匀,Zn和Ni形成了均匀的合金。沉积电位、沉积时间、沉积温度分别为2.5V、2h、353K的条件下,阴极为纯铜片,阳极为石墨片。以质量分数为5%的NaOH作为添加剂在EG-ZnCl2-MgCl2体系中制备出了Zn-Mg合金。采用循环伏安法研究了体系的电化学性质；采用EDS、XRD和XPS等手段对镀层进行了分析。其结果表明：Zn-Mg合金的沉积是一个分步进行的过程。先发生Zn的沉积,之后发生Zn-Mg合金的共沉积；镀层呈疏松多孔的絮状分布；Mg和Zn形成了非晶态的固溶体,镁的存在形式分别有Mg和MgO；锌的形式是以锌单质存在。
[Abstract]:Zinc alloy as a new type of protective coating has been widely concerned, because of its good formability, solderability, varnish, widely used in aerospace, automotive. The traditional production methods of zinc-nickel alloy are melting method and electroplating method. The zinc nickel alloy produced by melting method has poor dispersion degree and the nickel content in the alloy is low. Electroplating is mainly acidic and alkaline aqueous solution, because it is not friendly to the environment, so its application in industry is affected. The production methods of zinc and magnesium alloy are hot plating and vacuum plating. Molten salt electroplating, vapor deposition and so on. Now the focus of research on zinc magnesium alloy coating is mainly in sulfuric acid aqueous solution, the magnesium content in the coating is low. Therefore, to seek a low cost, simple process. The preparation method of green zinc alloy is of great significance. Based on the above situation we use EG-ZnCl2 ionic liquid and urea zinc chloride nickel chloride low eutectic salt system as electrolyte. The electrodeposition of zinc magnesium alloy and zinc nickel alloy was studied. The two electrolytes not only have the advantages of green and environmental protection, but also have the advantages of low cost, simple system and insensitive air. It can be operated in exposed air, which meets the requirement of sustainable development of green production process. The conductivity of ionic liquids formed when ZnCl _ 2 / NiCl _ 2 ~ (2 +) Urea content is different has been determined. The electrochemical properties of Zn-Ni alloy were studied by means of chronoamperometry and cyclic voltammetry. The deposition conditions were optimized by response surface method. EDS and XRD were used to analyze the coating. The results show that the conductivity of the system is the best when the mole ratio of w ZnCl 2: NiCl 2: U is 2. 9: 1. 5: 16. 7. The relationship between conductivity and temperature accords with the Arrhenius formula, and the activation energy of the ionic liquid solution is 30.733kJ / mol. The electrocrystallization of Zn-Ni goes through the nucleation process, and the electric crystallization process is carried out according to the instantaneous nucleation process. In the cyclic voltammetry curve of Urea-ZnCl2-NiCl2 ionic liquids without sweep velocity, the peak current of reduction increases with the increase of sweep speed. The effect of deposition temperature on the mass fraction of zinc in the coating is smaller than that of EG addition and deposition potential. The optimized deposition condition is that the mass fraction of EG is 28.4%. The deposition potential is 2.1 V and the deposition temperature is 358K; The coating is composed of spherical particles with an average particle size of 2.5 渭 m, no cracks and no voids, and is a solid solution of Zn-Ni alloy. The average diameter and thickness of the coating are less than 1 渭 m and 20 渭 m respectively, and the bonding degree between the coating and the substrate is good and smooth. The uniform distribution of Zn and Ni in the coating formed a uniform alloy. The deposition potential, deposition time and deposition temperature were 2.5V / 2h ~ 353K, respectively. Cathode is pure copper sheet. The anode is graphite sheet, the Zn-Mg alloy is prepared in EG-ZnCl2-MgCl2 system with NaOH of 5% mass fraction as additive. Cyclic voltammetry is used to study the electrochemical properties of the system. The nature of science; The deposit was analyzed by means of EDS-XRD and XPS. The results show that the deposition of Zn-Mg alloy is a step by step process, and the deposition of Zn occurs first. Then codeposition of Zn-Mg alloy occurred. The coating is porous and flocculent. Mg and Zn formed amorphous solid solution, and mg and MgO existed in mg and MgO respectively. Zinc exists in the form of zinc.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ153.2

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