Robust, fluorine-free, bioinspired PU superhydrophobic composite coating based on modified ceramics nanoparticle: Preparation, characterization and mechanism

Abstract

The corrosion failure of aluminum‑lithium (AlLi) alloy, extensively used in aerospace and industry area, inevitably brings about considerable economic loss. In this work, stearic acid (STA) is utilized as a modulator for the low surface energy modification of TiO₂ particle. Polyurethane (PU) is employed as a binder to ensure the firm adhesion of modified STA@TiO₂ to AlLi alloy through a controllable and low-cost spraying process. Such structure design brings about a robust preparation of STA@TiO₂/PU superhydrophobic coating for large-scale engineering application. The resultant coating exhibits a static water contact angle (CA) of 161.3 ± 0.8°, and a sliding angle (SA) of 3.1 ± 0.7°. The subsequent characterizations of surface morphology and chemical structure are performed using SEM, EDS, XPS, and laser confocal microscopy. Furthermore, the contrastive electrochemical impedances and kinetic potential polarizations are investigated on as-prepared coating and AlLi alloy substrate. The results indicate that the impedance modulus of STA@ TiO₂/PU coating is enhanced by two orders of magnitude, while the corrosion potential demonstrates an increasement of 180 mV. The experimental tests confirm a significant improved corrosion resistance for STA@ TiO₂/PU coating. Moreover, the effective self-cleaning, anti-pollution, buoyancy enhancement and anti-icing properties are discussed, and the corresponding interface behaviors and function implementation mechanisms are also systematically investigated. The findings have positive implications for expanding industrial applications of such multi-functional ceramic coatings in engineering construction, environmental protection, and harsh working conditions.