One-step fabrication of superhydrophobic nanocomposite with superior anticorrosion performance

Abstract

Superhydrophobic coatings having a self-cleaning ability and anticorrosion performance are desired in many industrial contexts; however, high costs and complex fabrication methods limit their application. In this study, thin anticorrosive superhydrophobic coatings were prepared by a scalable, simple, and inexpensive spraying method to protect AA2024-T3 surfaces. The two-component coatings were designed using fluoropolyurethane and varying concentrations of surface modified silica nanoparticles. Surface characterization was performed using contact angle and contact angle hysteresis measurements, field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectrum (EDS), and atomic force microscopy (AFM) techniques. Corrosion protection, water uptake, and adhesion strength of the coatings were evaluated by electrochemical impedance spectroscopy (EIS) and cross-cut tests, respectively. Increased silica nanoparticle concentrations up to 10 wt% led to increased contact angles from 92° to 167°. The lowest contact angle hysteresis was obtained for the coating containing 4 wt% nanoparticles. FE-SEM images showed that high concentrations of nanoparticles (more than 4 wt%) led to cracks in the coating surface. The best performance of a coating was observed when the coating contained 4 wt% nanosilica particles, resulting in a 164° water contact angle, almost 60 days of surface protection, an impedance value of 2.2 × 109 Ω·cm2, 0.9% water uptake, and marked adhesion strength. The impedance value of the coating with 4 wt% nanosilica particles was about 25× that of the blank sample.