【作者】 郑军；

【导师】 潘勇；

【作者基本信息】 湘潭大学 ， 材料物理与化学， 2011， 硕士

【摘要】 扣式电池在微电子行业有较为广泛的应用。在碱性锌锰扣式电池中,由于负极锌粉或锌膏会与杂质金属发生析氢反应,产生大量气体,使电池鼓胀,进而使电池失效甚至产生安全问题。为了解决该问题,传统的方法是在负极锌粉或锌膏中添加一定量的金属汞,汞与负极盖内壁的铜镀层反应生成汞齐,降低析氢腐蚀,抑制氢气的产生。但汞对人体和环境危害极大,电池无汞化是电池发展的必然趋势。锡是现在应用较为广泛的一种环境友好度高的材料,而且锡能提高负极锌粉的析氢过电位,降低析氢腐蚀。开发无汞扣式电池时,通常在负极盖内壁的铜上电镀一层锡,锡镀层能阻挡无汞负极锌粉等材料与铜的直接接触,从而降低析氢腐蚀,减小电池的气胀率,然而现有的扣式电池生产厂家,在生产负极盖过程中,绝大多数采用先对带材进行电镀锡,再冲压成负极盖的生产工艺。常规的镀锡带材在冲盖过程中存在表面易划伤,裂纹多,露铜等不足,使得电池气胀率高,阻碍了无汞扣式电池的发展和规模化应用,因此解决锡镀层的致密性和硬度问题是促进无汞扣式电池产业化的关键所在。为了解决上述问题,本文采用脉冲电沉积方法,改变脉冲参数等工艺条件,在铜带上制备不同晶粒尺寸的锡镀层,并用XRD、SEM、EDS等测试方法对锡镀层的微观结构、镀锡铜带拉伸变形后耐腐蚀性能进行了研究,具体内容如下:1.在深入研究传统的锡镀层电沉积工艺的基础上,改进了工艺配方,采用脉冲电沉积方法,分别改变了脉冲占空比、脉冲频率、双向脉冲正反电流比等参数,制备出镀层厚度均为4μm的锡镀层。2.对所制备的样品进行表面形貌和相结构的表征,研究了三种脉冲参数对锡镀层微观结构的影响规律。结果表明:(1)随着脉冲占空比的增大,镀层表面晶粒尺寸增大,孔隙率增高,晶粒的生长择优取向逐渐从Sn(101)晶面向Sn(211)晶面转变;(2)随着脉冲频率的增大,晶粒尺寸减小,孔隙率降低,晶粒的生长择优取向从Sn(211)晶面向Sn(101)晶面转变;(3)随着双向脉冲正反电流比的减小,镀层晶粒逐渐增大,晶粒的生长择优取向从Sn(101)晶面向Sn(211)晶面转变。3.测试不同脉冲参数下得到的不同锡镀层的硬度值,研究脉冲参数与锡镀层硬度值之间的关系;对样品进行拉伸,采用电化学工作站对样品的耐腐蚀性能进行研究,得到脉冲参数对样品的硬度与拉伸后裂纹的变化以及耐腐蚀性能之间的关系。结果表明:(1)随着脉冲占空比的增大,镀层的硬度逐渐降低;拉伸后镀层的表面裂纹逐渐减小,其耐腐蚀性能也逐渐增强;(2)随着脉冲频率和双向脉冲正反电流比的增大,镀层的硬度明显增大;拉伸后镀层的表面裂纹逐渐增大,其耐腐蚀性能逐渐降低。更多还原

【Abstract】 Button battery is widely used in micro-electronics industry. In the alkaline zinc-manganese button battery, the battery may expand and bring the safety problems due to the hydrogen evolution reaction between anode zinc powder or the zinc oil and the impurities, which can produce large amounts of gas. To solve this problem, the traditional method is to add a certain amount of metal mercury which can react with the copper coating in the anode lid to produce amalgam and lower hydrogen evolution corrosion, so as to restrain the production of hydrogen. However, the mercury is greatly badly to body and environment and mercury-free battery is an inevitable trend in the development of the battery. Tin is friendly to the environment and it can improve the hydrogen evolution reaction over-potential and reduce the hydrogen evolution. In the development of mercury-free batteries, the tin coating is always electroplated on the copper of the anode lid, which can hold the contract of anode zinc powder with copper so as to lower hydrogen evolution corrosion and decrease the expansion of the battery. Now the existing battery producers always take the technology that make the anode lid stamping forming after electroplating tin on the strip substrate, while there are many problems during stamping forming such as being scratched easily, many cracks and expose copper and so on, leading to the expansion of battery for the conventional tin coating strip, which hinders the development and wide use of the mercury-free batteries, so it is very important to solve the problem of the densification and hardness of the tin coating for the industrialization of mercury-free button batteries. To settle the matter, in this thesis, the tin coating of different grain size were prepared by pulse electroplating on the copper substrate with different technological conditions such as pulse parameters. Many measurement method, XRD, SEM, EDS were used to analysis the micro-structure and the corrosion resistant property after tensile deformation of the samples. The details are followed.1. On the foundation of thorough study on the conventional tin electroplating technology, the technology formula were improved, and the pulse electroplating method is used to prepare tin coating with 4μm thickness when pulse parameters such as the pulse duty, frequency, ratio of double direction pulse current of pros and cons were changed respectively.2. The effects of the three pulse parameters, the pulse duty, frequency, ratio of double direction pulse current of pros and cons, on the micro-structure were studied on the basis of characterization of the surface morphology and phase. The results showed, first, the grain size of the tin coating and the porosity increased with the increase of the pulse duty, and the texture of the tin coating transformed from Sn(101) to Sn(211). Second, the grain size of the tin coating and the porosity decreased with the increase of the frequency, and the texture of the tin coating transformed from Sn(211) to Sn(101). Third, the grain size of the tin coating increased gradually with the decrease of ratio of double direction pulse current of pros and cons, and the texture of the tin coating transformed from Sn(101) to Sn(211).3. The hardness of the tin coatings prepared in different pulse conditions are tested, and the relations between the hardness of the tin coatings and the pulse conditions were studied. The corrosion resistant properties after tensile deformation of the samples were estimated by the electrochemical workstation. The relations between the pulse conditions and the hardness, the change of the cracks and the corrosion resistant properties after tensile deformation were observed, and the results were showed as follows. First, the hardness of the tin coatings decreased, the surface cracks reduced gradually, and the corrosion resistant properties were improved with the increase of the pulse duty. Second, the hardness of the tin coatings increased notably, the surface cracks extended gradually, and the corrosion resistant properties were diminished with the increase of the ratio of double direction pulse current of pros and cons.更多还原