Hybrid additive and subtractive manufacturing of metallic biomimetic non-smooth superhydrophobic surfaces

Metallic superhydrophobic surfaces have promising applications in pipeline transportation, shipbuilding, and biomedical fields because of their self-cleaning and anti-corrosion properties, and can be fabricated through bioinspired designs of non-smooth microstructures. When mimicking the hierarchical patterns found on butterfly wings, periodic ripples and pit defects develop naturally on the surface of additive manufacturing components that are formed layer-by-layer via laser powder bed fusion (LPBF). These inherent LPBF surface imperfections are refined by electrochemical polishing, chemical etching, and fluorosilane modification, resulting in multiscale biomimetic, nonsmooth superhydrophobic structures. Through hybrid additive and subtractive manufacturing techniques, a uniform pit-shaped micro/nanocomposite structure with a contact angle exceeding 150° is achieved, significantly enhancing the corrosion resistance of the surface. Finally, a complex superhydrophobic groove structure with an excellent self-cleaning performance was successfully fabricated, demonstrating that the approach of utilizing inherent processing defects to create functional surfaces can be extended to other metallic additive manufacturing technologies.