Nanofluid-infused slippery surface: Bioinspired coating on Zn with high corrosion inhibition performance

Abstract

Zn coating is widely used for protecting building construction surfaces exposed to atmospheric conditions. Due to the intrinsic chemical reactivity of Zn, it can be corroded by adventitious environmentally present corrosive species. Finding an effective protecting approach is critical in order to extend the life of a zinc coating and the substrate metal. In this work, using a facile salt spraying method, a porous matrix is formed on a Zn surface. After modification with dodecanethiol, the as-prepared porous matrix exhibits superhydrophobicity with a large water contact angle (WCA) of 158°. An upgraded bio-inspired slippery surface with high water-repellency is achieved by filling the nanofluid (NF) composed by nanoscale Fe3O4 and oleic acid into the pores on Zn (NF Zn). Surprisingly, this coating exhibits a sustainable anti-corrosion capability. The characteristic impedance of NF Zn coating increases 6 orders of magnitude in 3.5 wt% and 7.0 wt% NaCl aqueous solution, and the corrosion current density (Icorr) decreases by 4 and 5 orders of magnitude, respectively. After the salt spray test for 21 days, it still has a good protection effect on metallic zinc. In an acidic environment, the characteristic impedance of NF Zn increases 5 orders of magnitude, and Icorr decreases 4 orders of magnitude than that of bare Zn, performing a good anti-corrosion effect. After immersion for 16 days, the low-frequency impedance and current density of NF Zn increase and decrease by 5 and 6 orders of magnitude, respectively. NF can be used as an anti-corrosion coating to protect Zn in different environments.