Superhydrophobic PFDTES@ZnO/PU coating for corrosion protection of Al-Li alloys

Abstract

Aluminum-lithium (Al-Li) alloys are widely used in marine environments because of their low density and high strength, but they are susceptible to corrosion during service. In this work, a durable and multifunctional PFDTES@ZnO/PU superhydrophobic coating was fabricated on an Al-Li alloy substrate by a simple and economical spraying method using PFDTES-modified ZnO nanoparticles and polyurethane as the binder. The surface morphology, chemical composition, wettability, corrosion resistance, durability, and multifunctional properties of the coating were systematically investigated. The prepared coating showed a water contact angle of 160.07° ± 0.8° and a sliding angle of 3.4° ± 0.6°. Electrochemical tests indicated that, compared with the bare substrate, the coating exhibited an impedance modulus increased by about two orders of magnitude, a positive shift in corrosion potential of 215 mV, and a corrosion inhibition efficiency of 99.7%. After a 10 d NSS test, 15 d semi-immersion in 3.5 wt% NaCl solution, 7 d UV irradiation and 7 d outdoor exposure, the coating still maintained stable superhydrophobicity and structural integrity. In addition, the coating exhibited excellent self-cleaning, anti-pollution, drag-reduction, anti-icing, and antibacterial properties. These results demonstrate that the PFDTES@ZnO/PU coating can effectively integrate corrosion protection, durability, and multifunctionality, showing promising potential for marine applications of Al-Li alloys.

Keywords

superhydrophobic coating / polyurethane composite / corrosion resistance / self-cleaning properties / antibacterial properties

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Central South University