Enhanced corrosion protection of superhydrophobic SiO2/epoxy composite coatings for aluminum alloys with 8-HQ incorporated MSNs containers

Background Superhydrophobic coatings have shown great promise in providing temporary corrosion protection for aluminum alloys. However, their long-term effectiveness is often compromised by poor mechanical durability and the lack of active protection. Methods In this study, we developed a novel protection coating by integrating a functional epoxy primer containing 8-hydroxyquinoline-loaded mesoporous SiO 2 nanocontainers (8-HQ@MSNs) and a superhydrophobic SiO 2 topcoat. Significant findings After chemical and structural characterization of 8-HQ@MSNs, its optimized content is determined to be 0.5 %. The resulting coating provides long-term protection for aluminum alloys in 3.5 wt. % NaCl solution over 30 days. Notably, the low-frequency impedance modulus of the scratched coating, even after immersion in NaCl solution for 12 h, is one order of magnitude higher than that of the coating lacking 8-HQ with a shorter corrosion duration (6 h). Furthermore, this coating exhibits a strong interfacial bond with aluminum alloys (Grade 0) and can withstand an abrasion distance of 1360 cm on 600 grit sandpaper under a 100 g load, as well as 140 min of continuous high-pressure water impact (25 kPa) without losing its superhydrophobic properties. This study is expected to contribute new insights into developing durable superhydrophobic coatings with active protection for aluminum alloys.