Fabrication of a Tool Electrode with Hydrophobic Features and Its Stray-Corrosion Suppression Performance for Micro-electrochemical Machining

Abstract

Micro-electrochemical machining (micro-ECM) can machine microstructures with excellent surface integrity on difficult-to-cut alloys. During micro-ECM, stray corrosion results in tapered sidewalls of machined structures. To suppress the stray corrosion, a novel tool electrode with the sidewall insulation of a gas film is proposed by fabricating the metal tool sidewall into a hydrophobic surface. The sidewall surface is designed to be characterized with spherical array cavities (radius of 500 nm) acting as the hydrophobic features, enhancing the gas-shielding effect of the gas film under electrolysis. The fabrication process of the hydrophobic sidewall is described in detail, including the self-assembly procedure of a monolayer template of Φ1 μm polystyrene microspheres, the copper-electroforming procedure for filling the microspheres’ gaps, and the removal procedure for forming spherical array cavities. The fabricated tool electrode (Φ500 μm) obtains the hydrophobic features of a contact angle of up to 138°. As a result, bubbles generated on the tool surface can form an air–electrolyte interface instead of a dispersed bubble cluster. Micro-ECM experiments of microstructures verify that the novel tool electrode can improve machining accuracy by suppressing sidewall stray corrosion.

Tooling aspects of micro electrochemical machining (ECM) technology: Design, functionality, and fabrication routes

“…During the fabrication process, polystyrene microspheres with a diameter of 1 μm were arranged to form the monolayer, and copper was deposited to fill the gaps of microspheres by electroforming in Fig. 37(b) (Liu et al, 2022a). surface acting as the hydrophobic features (Liu et al, 2022a).…”

Electrochemical machining of hole structures by using superhydrophobic tube electrode

“…With the dissolution of the anode, tiny bubbles will be generated on the cathode electrode and begin to accumulate on the surface of the electrode. Finally, a dynamic gas film [8] is formed, which has a positive effect on the suppression of stray corrosion.…”