Fabrication of robust superhydrophobic zinc-coated steel with anti-corrosion and self-cleaning behavior through a simple nickel galvanic replacement reaction

Abstract

Zinc coating is a widely used coating for steel substrate as a galvanic protector but the corrosion rate of this coating increases when exposed to wet environment. In recent years, bioinspired superhydrophobic surfaces have received tremendous attention among various methods to enhance the corrosion resistance. In this study, superhydrophobic zinc-coated steel was fabricated based on nickel galvanic replacement reaction in NiCl2.6 H2O solution on zinc-coated steel and post modification to improve the corrosion resistance and create self-cleaning behavior. Based on the FESEM morphology and AFM topography images, galvanic replacement reaction created hierarchical micro/nanostructure that is key parameter for creating superhydrophobic surfaces. EDS, XRD, XPS and FTIR analysis confirmed the occurrence of galvanic replacement reaction and post modification of the surface with FAS- solution. The zinc-coated steel immersed in NiCl2.6 H2O solution with the concentration of 0.1 M for 10 min showed the highest water contact angle of 166.7° ± 1.6° and a contact angle hysteresis of 1.7°. In addition, it exhibited good long-term stability under various conditions, mechanical stability, self-cleaning capability, and robust adhesion which was not reported, previously. Corrosion study showed that the surface exhibit excellent charge transfer resistance and higher positive corrosion potential and a lower corrosion current density compared with the zinc coating. The results indicated that the galvanic replacement reaction is a simple, scalable, cost effective and promising method for creating multifunctional and robust superhydrophobic surfaces on zinc coatings to protect steel.