Coating-Free Superhydrophobic Hard Surfaces by Electric Discharge Machining with a Magnetic-Assisted Self-Assembly Sheet Electrode

Artificial superhydrophobic surfaces hold significant potential in various domains, encompassing self-cleaning, droplet manipulation, microfluidics, and thermal management. Consequently, there is a burgeoning demand for cost-effective, mass-producible, and easily fabricated superhydrophobic surfaces for commercial and industrial applications. This research introduces an efficient, uncomplicated method for constructing hierarchical structures on hard substrates such as binderless tungsten carbide (WC) and glass substrates. The WC substrates were processed by using electrical discharge machining (EDM) with a magnetic-assisted self-assembly sheet electrode. The resultant surfaces comprised micropillars/microgrooves and diminutive craters formed by discharge and ablation, respectively. These surfaces exhibited superior hydrophobic properties, which can be attributed to the modified surface energy and surface texture construction. Our study indicates that a superhydrophobic surface can be achieved on a textured binderless WC. The maximum contact angle and minimum roll-off angle of the hierarchical structure induced by EDM with a magnetic-assisted self-assembly sheet electrode are about 158 and 5°, respectively. The advancing and receding angles are about 161° ± 2 and 157° ± 3, respectively, when the base is tilted at 3°. Furthermore, we have successfully replicated this superhydrophobic structured surface on glass substrates utilizing glass molding technology. This innovative approach to creating superhydrophobic surfaces on hard materials paves the way for the mass production of functional structures on other materials, such as metallic glass, titanium alloy, and mold steel. Most crucially, the proposed fabrication technique offers a straightforward, cost-effective route for creating functional surfaces, rendering it attractive for large-scale industrial production due to its considerable application prospects.