Hierarchical zeolite-LTA@Mg-Al layered double hydroxide core@shell structure with enhanced corrosion protection of steel in saturated Ca(OH)2 solution

Abstract In this article, a novel type of core@shell Linde type A zeolite@Mg-Al layered double hydroxides (zeolite-LTA@ Mg-Al LDHs) was fabricated via in situ co-deposition method for efficient corrosion protection of carbon steel. The corrosion inhibition effect of fabricated zeolite-LTA@ Mg-Al LDH on steel was decided by a comparative experiment in saturated Ca(OH)2 solution. The batch experiment on the equilibrium isotherms of chloride binding in the solution clearly demonstrated that compared to pure Mg-Al LDHs, the zeolite-LTA@Mg-Al LDHs exhibited an higher chloride binding capacity due to the highly dispersed LDHs with large surface area on the zeolite-LTA support. In addition, a better corrosion inhibition capacity of zeolite-LTA@Mg-Al LDHs was proved by the measurements of open-circuit potential (OCP), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PP) and optical microscopy (OM). Some nitrate ions on the steel surface detected by X-ray photoelectron spectroscopy (XPS) confirmed the dual effects of aggressive chloride removal and simultaneously released NO3−, which were responsible for the ultimate inhibition effect of zeolite-LTA@Mg-Al LDHs.