【作者】 陈斌；

【导师】 李寒松； 朱增伟； 周安全；

【作者基本信息】 南京航空航天大学 ， 工程硕士（专业学位）， 2017， 硕士

【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。更多还原

【Abstract】 Chromium plating layer is widely used in mechanical components because of its excellent wear resistance,color and high hardness.However,the traditional electroplated chromium layer has the penetrating crack,which looks like network that seriously affects the corrosion resistance and wear resistance of the parts.At the same time,due to the poor dispersion of the plating solution,the thickness of the coating is uneven,which increases the difficulty of the subsequent process.So the application of chromium plating is limited.In order to solve the above issues,the basic application of crack-free pulse plating hard chromium was studied,which was based on the free particle polishing-assisted process.The following work has been done:1.Experimental research of crack-free chromium electroplating based on the free particle polishing-assisted crack-free hard chromium plating process was carried out on the 300 M steel substrate.Influences of coating thickness and process parameters on microstructure,hardness,fatigued strength and wear resistance have been studied,analyzed and summarized.The results were following: chromium layer prepared by free particle polishing-assisted hard chromium plating had dense microstructure and no crack on the surface.Under certain process parameters,the hardness of chromium plating layer was between 750 HV to 850 HV,much higher than traditional hard chromium plating layer.Meanwhile,the wear resistance,shear strength and bending fatigue performance of the chromium plating layer were improved.The wear resistance increased with the increase of coating thickness,the decrease of current density,the decrease of cathode speed and the increase of pulse frequency.2.The COMSOL software has been used to simulate the auxiliary cathode,the insulation shield and the anode-cathode distance in order to improve the uniformity of the thickness of the chromium plating layer.The results showed that the thickness uniformity of chromium plating layer could be improved by using appropriate polar distance,auxiliary cathode with the same diameter of cathode and increasing the height of auxiliary cathode.3.The corresponding fixtures including the rotary sealing structure and electric structure have been designed based on different characteristics of revolving parts and the simulation results.The hard chromium plating experiments were carried by the suitable parameters on the basis of the rules obtained from the basic experiment.更多还原