【作者】 张艳萍；

【导师】 樊建锋；

【作者基本信息】 太原理工大学 ， 材料加工工程， 2012， 硕士

【摘要】 镁具有电池比容量高、环境友好、价格低廉、吸氢量大等特点,在新型的绿色电池、负极材料和储氢材料中越来越受到关注,被誉为“21世纪绿色工程材料”。与其他制膜方法相比,电化学沉积法具有很多优点如工艺简单、操作方便、污染小、能耗少、生产方式灵活等,是一种经济的薄膜制备方法,比较适于工业化生产。本论文采用电化学沉积法,成功制备出致密光亮的金属镁薄膜,并采用SEM、XRD和EDS对沉积金属镁薄膜的形貌、组织和成分进行分析。配制有机非质子极性溶剂乙基氯化镁/四氢呋喃(EtMgCl/THF)溶液作为镁电沉积电解液,采用循环伏安法研究了金属镁在基体材料纯铜带上的初始电化学沉积行为,研究发现,镁在铜基体上的薄膜生长遵循形核/生长机制。采用恒流电沉积法,通过改变电沉积时间、电解液浓度和电流密度,分别研究各参数对镁金属电沉积行为的影响,并探讨恒流电沉积下,镁金属薄膜的电结晶机理。结果表明,金属镁薄膜在基体铜上的生长方式属于核生长型。沉积膜层厚度和致密度随着电解液浓度和电流密度的增大而逐渐增大,但当厚度增大到一定程度时,膜层之间由于存在内应力而产生裂纹、变形、起皮、结合力降低等各种缺陷。沉积层晶粒尺寸在电解液浓度为0.54M、电流密度为-5mA/cm2时最小。采用脉冲电沉积法,通过改变电沉积时间、电流密度及脉冲占空比,分别研究各参数对镁金属电沉积行为的影响,探讨脉冲电沉积下,镁金属薄膜的电结晶机理,并对比研究了恒流和脉冲两种不同的电沉积方法对镁电沉积行为的影响。结果表明,脉冲沉积时晶粒在形核长大过程中存在某晶面的择优取向呈层状排列。随着电流密度的增大,膜层硬度和沉积速率大致呈增大的趋势,在不同的电流密度下,不同晶面存在着不同程度的择优取向。随着占空比的逐渐减小,晶粒尺寸也不断呈减小的趋势。更多还原

【Abstract】 Magnesium is known as the "Green engineering material of the21st century" because of its high theoretical capacity, low cost, environmental-friendly and absorbing a great amount of hydrogen, So magnesium has attracted more and more attention in many fields, especially in new type of green batteries, anode materials and hydrogen storage materials. Compared with other methods, electrochemical deposition have some advantages such as simple process, easy operation, vironmental safety, less energy consumption and flexible production mode, etc, so it is an economical preparation methods for thin film and suitable for industrial production. In this paper, some compact and bright magnesium films were successfully prepared by electrochemical deposition technology, and the morphology, microstructure and composition of magnesium films were characterized by using Scanning electron microscope (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS).Anhydrous ethylmagnesium chloride in THF (EtMgCl/THF) was prepared as electrolyte, and the initial electrochemical deposition behavior of magnesium on the copper matrix was studied by Cyclic voltammetry. The results show that the deposition of magnesium film followed the mechanism of nucleation and subsequent grain growth.The effects of various parameters, including deposition time, electrolyte concentration and current density, on the electrochemical deposition behavior of magnesium were studied by using direct-current plating method. The results show that the Growth pattern of magnesium film on the copper matrix followed Volmer Veber, and the deposition thickness and density gradually increases with the increase of electrolyte concentration and current density. While when the thickness increases to a certain extent, various defects such as deformation, cracks, binding reduced, peeling are appeared between the layers because of the internal stress. The minimum grain size of the deposit was prepared at0.54M EtMgCl/THF and-5mA/cm2.The effects of various parameters, including deposition time, current density and pulse duty cycle on the electrochemical deposition behavior of magnesium were studied by using pulse-current plating method, and the electrocrystallization mechanism was investigated in this paper. The effect of constant current electrodeposition and pulse electrodeposition method on the behavior of magnesium electrodeposition was comparatively studied. The results suggest a preferential orientation parallel to a certain crystallographic planes during the nucleation and growth process of the Mg crystals. With the increases of pulse current density, the deposition rate and the hardness of films increase. For different current densities, the preferred orientations of crystal growth are different. The grain sizes of deposites are reduced with the decrease of pulse duty cycle.更多还原