Fabrication of superhydrophobic surfaces on copper substrates via flow plating technology

The preparation of superhydrophobic surfaces on hydrophilic metal substrates depends on both surface microstructures and low surface energy. Composite electro-brush flow plating technology was developed to prepare appropriate microstructures leading to superhydrophilicity on copper surfaces. The effects of plating voltage and plating time on the coating surface structures and hydrophobicity were discussed. The surface morphology and chemical composition were characterised by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The results demonstrate that the prepared surfaces have the appearance of micro-nano hierarchical structures composed of submicron papilla-like Ni structures and nanoscale Al₂O₃ particles. After fluoridation, the coating surfaces prepared by proper parameters show superhydrophobicity with a water contact angle of 162° and a sliding angle of less than 10°. Tests of micro hardness, wear resistance and persistence show that the obtained superhydrophobic n-Al₂O₃/Ni coating surfaces have outstanding mechanical properties and stability. This sample preparation technique has prospective application in the large-scale and continuous production of superhydrophobic engineering materials.