A robust and multifunctional superhydrophobic coating based on natural palygorskite for corrosion protection of aluminum alloys

Biomimetic superhydrophobic surfaces have become an increasingly hot topic in the area of aluminum alloy protection. However, it remains a significant challenge to construct superhydrophobic coatings with reliable durability and multifunction through simple and economical strategies. In this study, we designed a novel superhydrophobic coating with a water contact angle of -165.0 degrees and a sliding angle of -2.4 degrees on Al alloys by spraying hydrophobically modified natural palygorskite (SH-PAL) on the pre-cured epoxy resin (EP). The resulting superhydrophobic coating (EP@SH-PAL) exhibits good mechanical resistance, UV resistance, hot water repellency, chemical stability, thermal stability, and self-healing capabilities against plasma etching. Corrosion tests reveal that the protection efficiency of the EP@SH-PAL sample is up to 99.98 %, which remains at a high value of 90.30 % even after 20 days of immersion in 3.5 wt% NaCl. This improved corrosion resistance is attributed to the synergistic physical shielding from the SH-PAL topcoat and the EP primer. Meanwhile, molecular dynamics simulations of the mechanical durability and corrosion resistance of the EP@SH-PAL coating were performed to support the experimental results at the microscopic level. In addition, the above-prepared superhydrophobic coating also demonstrates excellent self-cleaning and antifouling characteristics. This research will provide a new method for fabricating low-cost, multifunctional, superhydrophobic anticorrosion coatings on aluminum alloys and other metal substrates.