Synthesis of superhydrophobic SH-ZIF-NL and its influence on the anti-corrosion coating for magnesium alloy

A superhydrophobic layered nanocarrier, SH-ZIF-NL, was successfully synthesized, loaded with 2-mercaptobenzimidazole (2-MBI), and subsequently incorporated into polyvinyl butyral (PVB) resin to develop an advanced anti-corrosion composite coating tailored for magnesium alloy applications. The structural characteristics of the SH-ZIF-NL and its influence on the anti-corrosion performance of the PVB-based composite coatings were systematically investigated. The results indicate that the layered nanocarriers, with their stacked architecture, provide numerous active sites, which significantly enhance the loading capacity for the corrosion inhibitor. Furthermore, the hydrophobic functional groups on the surface modulate the release kinetics of the corrosion inhibitor, thereby prolonging its protective efficacy over an extended period. The 2-MBI@SH-ZIF-NL/PVB composite coating displayed remarkable advantages in enhancing the anti-corrosion performance of magnesium alloys. After immersion in a 3.5 wt.% NaCl solution for two months, the low-frequency impedance modulus of this composite coating remained stable without significant reduction. Even when the coating was damaged, it continued to provide short-term corrosion protection for the underlying magnesium alloy substrate. The exceptional anti-corrosion performance of this coating can be attributed to the superior physical barrier properties of the superhydrophobic layered nanocarrier, the intelligent and controlled stepwise release of the corrosion inhibitor, as well as the improved adhesion between the coating and the substrate.