无裂纹电镀硬铬应用基础研究

发布时间：2018-03-19 19:35

本文选题：电镀　切入点：摩擦辅助　出处：《南京航空航天大学》2017年硕士论文　论文类型：学位论文

【摘要】：镀铬层因其具有良好的耐磨性、光泽度以及高硬度被普遍应用在机械零部件上。然而,传统镀铬层存在网状贯穿性裂纹,严重影响了零件的耐腐蚀性和耐磨性;同时由于镀液分散能力差导致镀层厚度不均匀,加大了后续工艺难度。这两者都限制了电镀铬的应用范围。为了解决上述问题,本文基于游离粒子摩擦辅助电镀工艺技术,开展了无裂纹脉冲电镀硬铬应用基础研究。主要工作可分为以下几部分:1.基于游离粒子摩擦辅助电镀无裂纹硬铬工艺技术,在300M钢基材上进行基础实验,研究不同厚度及不同工艺条件对铬镀层的形貌、耐磨性、显微硬度及抗剪强度的影响,并对结果进行分析总结。结果表明:利用游离粒子摩擦辅助电镀硬铬工艺制备的铬层组织致密,表面无裂纹。在一定工艺参数下制备的镀铬层其显微硬度都在750HV到850HV之间,远远高于传统工艺。同时所得的镀铬层其耐磨性能和抗剪强度都有所提升。其中耐磨性能随着镀层厚度的增大、电流密度的减小、阴极转速的减小、脉冲频率的增大而提升。2.为提高镀铬层厚度均匀性,利用COMSOL软件对辅助阴极和绝缘环外形尺寸以及阴阳极间距进行电场仿真优化。仿真结果显示采用合适的极间距、与阴极相同直径的辅助阴极以及增加辅助阴极高度等均可提高镀铬层的厚度均匀性。3.基于不同回转体零件特征,根据仿真结果设计了相应夹具,包括旋转密封结构、引电结构等;依据基础试验得到的试验规律,选择了合适的加工参数进行了电镀硬铬实验;对试验后零件上的镀层进行了厚度均匀性检测。
[Abstract]:Chromium coating is widely used in mechanical parts because of its good wear resistance, gloss and high hardness. However, the traditional chromium plating layer has network penetration cracks, which seriously affect the corrosion resistance and wear resistance of the parts. At the same time, the coating thickness is not uniform due to the poor dispersion ability of plating solution, which increases the difficulty of subsequent process. Both of them limit the scope of application of chromium electroplating. In order to solve the above problems, this paper based on the free particle friction assisted electroplating technology, The basic research on the application of crack free pulse electroplating hard chromium is carried out. The main work can be divided into the following parts: 1. Based on the free particle friction assisted hard chromium plating technology, the basic experiment is carried out on 300M steel substrate. The effects of different thickness and process conditions on the morphology, wear resistance, microhardness and shear strength of chromium coating were studied. The results are analyzed and summarized. The results show that the chromium coating prepared by friction assisted electroplating with free particles has dense microstructure and no crack on the surface. The microhardness of the chromium coating prepared under certain process parameters is between 750 HV and 850 HV, and the microhardness of the chromium coating is between 750 HV and 850 HV, and the microhardness of the coating is between 750 HV and 850 HV. The wear resistance and shear strength of the chromium-plated coating are improved with the increase of coating thickness, the decrease of current density and the decrease of cathode speed. In order to improve the thickness uniformity of chromium plating layer, the shape size of auxiliary cathode and insulating ring and the distance between cathode and anode are optimized by COMSOL software. The simulation results show that the appropriate electrode spacing is adopted. The thickness uniformity of chromium-plated layer can be improved by the auxiliary cathode with the same diameter as the cathode and by increasing the height of the auxiliary cathode. Based on the characteristics of different rotary parts, the corresponding clamps are designed according to the simulation results, including the rotating sealing structure. According to the experimental rule of basic test, the suitable processing parameters were selected to carry out electroplating hard chromium experiment, and the thickness uniformity of the coating on the part after the test was tested.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ153.11

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