One-step self-assembly strategy for composite superhydrophobic coatings: Film-forming mechanism and performance evaluation

In this study, a composite superhydrophobic coating, primarily consisting of copper stearate, silane, and cerium compounds, was successfully constructed on galvanized steel surfaces via a one-step self-assembly method. The effect of self-assembly duration on coating performance was systematically investigated. Results showed that when the film-forming time reached 30 minutes, the coating exhibited optimal petal-like micro/nanostructures with a blue appearance, achieving a water contact angle (WCA) of up to 164° and a rolling angle (RA) as low as 2°, thus demonstrating excellent superhydrophobicity. The chemical composition and structural characteristics of the coating were clarified using SEM EDS, FT-IR, XRD, and XPS characterization techniques, confirming that the coating was mainly formed through the crystal growth of copper stearate coupled with the three-dimensional network crosslinking of silane. Electrochemical test results indicated that this coating reduced the corrosion current density of the substrate by three orders of magnitude while increasing the low-frequency impedance modulus by nearly three orders of magnitude, manifesting remarkable corrosion resistance. Further research revealed a dual protection mechanism: the air film formed on the superhydrophobic surface serves as an initial physical barrier; when the superhydrophobicity deteriorates, the cerium-based corrosion inhibitors in the coating can achieve self-healing functionality by forming insoluble corrosion products, thereby sustaining long-term protective effects. Additionally, the coating exhibited good mechanical stability (retaining a WCA of 156° after 30 abrasion cycles) and excellent adhesion (Grade 1). This study provides a novel technical strategy for the long-term anticorrosion protection of galvanized steel and offers theoretical basis and practical guidance for the preparation of multifunctional superhydrophobic surfaces.