Dual-Layer Anticorrosion Coating: Advanced Multifunctional Coating with Both Superhydrophobicity and pH-Responsive Behavior

This article prepared a multifunctional anticorrosion superhydrophobic dual-layer coating with pH-response behavior. By modification of ZIF-8 with low surface energy substance stearic acid, and then loading the corrosion inhibitor 2-amino-5-mercapto-1,3,4-thiadiazole (AMT), a superhydrophobic nanocontainer encapsulating the corrosion inhibitor was prepared. The first layer of the smart coating was applied by using a brushing technique, while the second layer of the superhydrophobic coating was achieved through a spraying method. This composite coating exhibits both pH-responsive behavior and superhydrophobic properties. An electrochemical impedance spectroscopy test was conducted by immersing the composite coating in a 3.5 wt % NaCl solution. The results indicated that the dual-layer superhydrophobic anticorrosion composite coating, designated as ZST/EP-S, maintained the highest low-frequency impedance value after 40 days of immersion, which was 4 orders of magnitude greater than that of pure EP and 1 order of magnitude higher than the smart anticorrosion coating ZST/EP. This demonstrates a significant enhancement in corrosion resistance for the dual-layer superhydrophobic anticorrosion composite coating. Scratch test and UV–vis light experiments verified the successful release of corrosion inhibitor AMT.