LDHs-based nanoreservoirs enhancing the corrosion protection of epoxy coatings for steel in concrete pore solutions

Abstract

Zn/Al-LDHs were firstly synthesized, and then, NO₂^- ions were exchanged into the interlayers of LDHs. The sustained release of NO₂^- ions from the \({\text{NO}}_{2}^{ - }\)-modified LDHs was confirmed in the simulated concrete pore solution. The \({\text{NO}}_{2}^{ - }\)-modified LDHs, acting as nanoreservoirs, were incorporated into an epoxy coating. The nanocomposite coating exhibits more durable corrosion protection for the steel substrate in comparison with the undoped coating in the simulated concrete pore solution. The improvement of corrosion resistance is attributed to the sustained release of \({\text{NO}}_{2}^{ - }\) ions with strong passivation ability from the nanoreservoirs. The excess incorporation of the nanoreservoirs is adverse to the corrosion protection of the nanocomposite coating. In addition, the self-repairing performance can be observed for the scribed nanocomposite coating in the simulated concrete pore solution.