Controllable vertical and radial corrosion by step flow fields for fabricating large aspect ratio micro-cone arrays in through-mask electrochemical micromachining

Ionic liquid electrospray thrusters (ILET) have the advantages of high efficiency, small size and low power consumption, and are widely used in micro and nanosatellite propulsion systems. As the core component of the electrospray thruster, the height and tip diameter of the micro-cone emitter array determine the performance of the thrust system. To increase the height of the micro-cone emitter, a through-mask electrochemical micromachining (TMEMM) processing method was proposed in this study. The eddy current generated under the mask in the low-speed flow field was innovatively used to make the gas and solid products gather on the processing side wall to form a product film, which effectively reduced the radial corrosion rate and achieved higher longitudinal processing. In sequence, high-speed flow field was applied to achieve high radial corrosion rate, high contour accuracy and high surface quality. By switching the low-speed flow field and the high-speed flow field, the vertical and radial corrosion rates were controlled. Finally, a microcone array with a height of 256.2 μm and a tip diameter of 20.3 μm was fabricated.