Sustainable corrosion-resistant superhydrophobic composite coating with strengthened robustness

In this paper, a superhydrophobic composite coating was developed employing epoxy resin (EP), polydimethylsiloxane (PDMS), and hexadecyltrimethoxysilane (HDTMS) functionalized Al2O3 nanoparticles as raw materials through a versatile and easily-scalable spray-coating technique. The water contact angle (WCA) and sliding angle (SA) of the designed superhydrophobic composite coating were 154.1 ± 0.7°and 3.5 ± 0.3°, respectively. The superhydrophobic composite coating features Cassie-Baxter phase contact, liquids repellency, anti-fouling, and self-cleaning properties for various liquid and solid contaminants. Compared with bare Q235 carbon steel, the charge transfer resistance (Rct) value of superhydrophobic composite coating immersed in the 3.5 wt. % NaCl solution can be remarkably enhanced by more than 7 orders of magnitudes with a corrosion inhibition efficiency of 99.99%. The coating maintain its superhydrophobicity, ultra-low adhesion force, and sustainable corrosion resistance even suffering 150 tape-peeling and 80 abrasion cycles. The improved durable mechanical robustness and interfacial bonding force can be attributed to the cross-linked and polymerized three-dimensional network micro-nano hierarchical structures formed by the combination of EP, PDMS, and embedded Al2O3@HDTMS nanoparticles. Besides, the accelerated salt-spray corrosion test (480 h) and atmospheric corrosion exposure (100 days) of the coating demonstrated superior anti-corrosion performance in both laboratory and real-world corrosive environments.