• CN:11-2187/TH
  • ISSN:0577-6686

机械工程学报 ›› 2019, Vol. 55 ›› Issue (7): 243-248.doi: 10.3901/JME.2019.07.243

• 制造工艺与装备 • 上一篇    下一篇

超声振动改善电铸表面粗糙度的机理

杨光, 胡志超, 张军, 皮钧, 刘中生   

  1. 集美大学机械与能源工程学院 厦门 361021
  • 收稿日期:2018-05-01 修回日期:2018-11-19 出版日期:2019-04-05 发布日期:2019-04-05
  • 通讯作者: 杨光(通信作者),女,1971年出生,博士,教授。主要研究方向为精密加工、电化学加工。E-mail:yangg@jmu.edu.cn
  • 作者简介:胡志超,男,1975年出生,副教授。主要研究方向为电化学加工。E-mail:hzc0204@163.com;张军,男,1966年出生,博士,副教授。主要研究方向为流体力学。E-mail:bull0202@sina.com;皮钧,男,1962年出生,博士,教授。主要研究方向为精密加工、超声加工技术。E-mail:pijun@jmu.edu.cn;刘中生,男,1960年出生,博士,教授。主要研究方向为机械动力学和精密加工。E-mail:liuzhongsheng@jmu.edu.cn
  • 基金资助:
    国家自然科学基金(51175225)、福建省科技重点(2017H0025)和福建省自然科学基金(2017J01700)资助项目。

Mechanism of Improved Surface Roughness in Electroforming Assisted by Ultrasonic Vibration

YANG Guang, HU Zhichao, ZHANG Jun, PI Jun, LIU Zhongsheng   

  1. College of Mechanical and Energy Engineering, Jimei University, Xiamen 361021
  • Received:2018-05-01 Revised:2018-11-19 Online:2019-04-05 Published:2019-04-05

摘要: 探讨超声振动改善电铸表面粗糙度的机理。试验表明,阴极板的超声振动能明显改善电铸层表面的粗糙度。对其机理,归纳为三点:①阴极板的超声振动使得电铸液在其边界层(阴极板附近的一个电铸液薄层)内产生众多的小涡流,其旋转方向以超声频率交替更换,这就使得镍离子浓度(垂直于电铸表面方向)在边界层内更趋于均匀化,提高了镍离子在边界层内的有效扩散系数;②阴极板边界层内更加均匀的镍离子浓度分布,抑制了肌瘤和枝晶的生长;③阴极表面生成的氢气核,在其初级阶段,被超声微射流驱除,无法继续生长,从而使微小气孔等缺陷得到了抑制,同时,也降低了氢离子在阴极析出的反应速率,改善了电流效率。阴极板的固有振动模态计算、阴极板边界层的流场模拟、镍离子扩散系数的计算数据、电铸表面粗糙度测量和电子显微镜图像,都支持这个机理。

关键词: 超声振动, 粗糙度, 电铸, 机理, 结晶, 扩散

Abstract: A mechanism is proposed that can explain the improvement of surface roughness in electroforming assisted by ultrasonic vibration. Experiments have shown that ultrasonic vibration, in particular, ultrasonic vibration from a cathode plate can significantly improve surface roughness in electroforming. Building upon our experiments, the mechanism is summarized as the following three points. (1) Ultrasonic vibration from the cathode plate produces numerous eddies in the boundary layer on the top of the cathode plate, alternating the flow directions of eddies at an ultrasonic frequency, and as a consequence, the electrolyte in the boundary layer is well mixed leading to evener distributions of the concentration of nickel ions. In another words, the effective diffusion coefficient of nickel ions in the electrolyte is increased by ultrasonic vibration. (2) The evener distributions of the concentration of nickel ions suppress the growth of dendrites and bumps. (3) Ultrasonic microjet from the cathode plate can drive tiny nuclei of hydrogen gas at the initial stage of their formation inhibiting the continuing growth of tiny gas (needle) hole. In this way, the rate of hydrogen production is decreased with the efficiency of electric current improved. The mechanism is supported by the calculation of the natural vibration modes of the cathode plate, the numerical simulation of the flow field of electrolyte in the boundary layer, the numerical simulation of the effective coefficient of nickel ions in the electrolyte, and the measurement of surface roughness and the SEM images of the surfaces fabricated by the electroforming.

Key words: crystallization, diffusion, electroforming, mechanisms, surface roughness, ultrasonic vibration

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