Robust, scalable and fluorine-free superhydrophobic anti-corrosion coating with shielding functions in marine submerged and atmospheric zones.

[Display omitted] • Superhydrophobic ZnO@STA@PDMS coating was designed via spraying method. • The coating possesses fluorine-free, substrate-independent and robust properties. • EIS and polarization results present greatly enhanced corrosion resistance. • A new salt-deliquesce self-coalescence anti-corrosion mechanism was proposed. • The coating provides promising applications in marine submerged and atmospheric zones. Biomimetic superhydrophobicity endows various substrates with amazing multi-functional properties. However, fragile hierarchical structures, fluorine-containing chemicals usage, and strict requirements for substrate scopes remain thorny challenges. Herein, we constructed a mechanical robust superhydrophobic ZnO@STA@PDMS coating with fluorine-free reagents through wide-applicable and substrate-independent spray-coating method. Field-emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and contact angle meter were used to assess the surface micro-nano structures, chemical compositions, thermal stability and wettability variations. The corrosion resistance of the developed superhydrophobic ZnO@STA@PDMS coating was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. The corrosion current density (I corr) of the substrate reduces by two orders of magnitude after being spray-coated with superhydrophobic ZnO@STA@PDMS coating, indicating excellent corrosion resistance in marine submerged zone. In simulated marine atmospheric conditions with high relative humidity, the salt-deliquesce behaviors of single and double NaCl particles on bare and coated Q235 carbon steel surfaces were recorded. In a high humidity atmospheric environment, the instantaneous salt-deliquesce self-coalescence phenomena provides a new type of anti-corrosion mechanism. Furthermore, the prepared superhydrophobic coating can withstand more than 30 tape-peeling cycles and 400 cm abrasion distance, demonstrating good mechanical stability in prospective real-world applications. [ABSTRACT FROM AUTHOR]