Investigation on particle assisted through-mask electrochemical etching of micro pit array

Microstructures are applied in various fields to improve the friction and lubrication of mechanical components. Through-mask electrochemical etching (TMEE) has shown good feasibility in machining microstructure array. However, the machining precision of microstructures gradually decreases with increasing etching depth in TMEE. Localization and uniformity are essential indicators of machining precision in TMEE. This study proposed the particle assisted through-mask electrochemical etching (PA-TMEE) method to increase localization and uniformity. Firstly, a coupled multi-physical field model, including gas–liquid two-phase flow, particle motion, and electrochemical processes, was established and adopted to predict the profiles of micro pits. Secondly, the comparison experimental results show that using PA-TMEE instead of TMEE resulted in improved localization and uniformity of the micro pit array. Then, the paper analyzed the effect of particle diameter and content on micro pits. When the particle diameter was 40 μm and the particle content was 6 g/L, the maximum etching depth was 58 μm. The etching factor was 2.4. The minimum coefficient of variation of the diameter and depth of micro pits was 3.3% and 5.2%, respectively. Finally, based on scanning electron microscopy and energy-dispersive spectrometer analysis, the machining mechanism of the PA-TMEE method is composed of particle erosion and electrochemical etching.