Fabrication of different shapes of tool electrodes using a variable-parameter bipolar-pulsed liquid membrane electrochemical etching method

Abstract

With traditional liquid membrane electrochemical etching methods, it is difficult to effectively control the electrolytic products. In this paper, a variable-parameter bipolar-pulsed liquid membrane electrochemical etching technique is proposed for the preparation of microelectrodes. The introduction of negative voltage will generate insoluble electrolytic products on the electrode surface. By adjusting the processing parameters, these electrolytic products can be precisely controlled, thereby shaping the morphology of the electrodes. In step one, the positive voltage is larger and the electrode surface is coated with a layer of insoluble electrolytic products. In step two, the positive voltage is smaller and hydrogen is generated on the electrode surface, dispersing the electrolytic products. The effects of positive voltage, negative voltage and processing time on the distribution of electrolytic products and electrode morphology were investigated in different steps. It was found that the upper and lower electrodes changed significantly with the change of processing time. Based on the experimental results, the droplet-shaped upper electrode and conical-shaped lower electrode with tiny size and controllable shape were prepared. In addition, a repeated-variable-parameter method was used to mitigate the problem of inconsistent etching speed that was caused by the electrolytic product coating, and enabled the preparation of cylindrical electrodes that are uniform in size. While keeping the processing mode unchanged, different shaped electrodes can be manufactured by simply adjusting the parameters to control the distribution of electrolytic products, demonstrating good processing flexibility.