A robust and repairable superhydrophobic Co5Zn21 alloy surface on a zinc substrate

Abstract

Herein, on a zinc substrate, a superhydrophobic Co₅Zn₂₁ alloy surface with a nanometer needle structure was fabricated by immersing processed Zn sheets perpendicularly into a cobalt(II) nitrate aqueous solution followed by the annealing treatment. This alloy surface exhibited not only outstanding superhydrophobicity with a water contact angle of 160° but also excellent mechanical durability and corrosion resistance. The morphology and chemical composition of the superhydrophobic surface (SHS) were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction pattern (XRD), energy-dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The corrosion resistance of the samples was characterized via polarization, Nyquist, and bode modulus plots. The SHS endures mechanical stretch for more than 800 mm of abrasion using sandpaper with different grit sizes (P1200, P800, and P400) and shows abrasion resistance. When the superhydrophobic surface lost its superhydrophobicity after a long-term damage, the superhydrophobicity could be easily regenerated again by immersion and annealing treatment. The surface after repair can still maintain its superhydrophobicity after anti-friction, anti-ice, and UV irradiation tests.