Cross-scale electrochemical machining of superhydrophobic end face cavities via microstructured surface cathodes

Abstract

In order to solve the problems of low precision of the electrochemical machining cavity and poor end face quality, this paper proposed a microstructured surface cathode and established the electrical and flow field models of the machining process. Theoretical analysis and simulation results show that the microstructure surface is helpful to improve the current density of the machining gap, and due to the superhydrophilic characteristics of the surface, hydrogen bubbles are promoted to separate from the cathode surface, the volume fraction of hydrogen bubbles in the end gap is reduced, and the mass transfer efficiency of the electrolyte is improved. A nanosecond laser machining system is used to prepare the array microstructure on the cathode surface. Compared with the experimental results of the original cathode, the feed rate of the proposed cathode increased from 0.10 mm/min to 0.20 mm/min and the machining process is more stable. The standard deviation of the width along the cavity depth direction is reduced from 285 μm to 175 μm, improving the machining accuracy of cavity. In addition, the microstructure on the cathode surface is replicated on the cavity end face and the reasons for the differences in size and shape between the micro-pit structure on the cavity end face and the microstructure on the cathode surface are analysed. The static contact angle of the cavity face is measured to be 150.5°, demonstrating excellent superhydrophobic properties. This method realizes cross-scale electrochemical machining of millimetre-scale cavities and micron-scale pits.