Stabilization and Protection of Catechins on Simulated Archaeological Iron

To effectively select natural corrosion inhibitors for archaeological iron objects, Fourier transform infrared spectroscopy, X-ray diffraction, electrochemical impedance spectroscopy, polarization curves and scanning electron microscopy were used to study the corrosion inhibition and protection effect of catechin in 3.5 g/L NaCl solution for naked and rusted hypereutectic white cast iron. The results show that catechin was a corrosion inhibitor that mainly inhibited anodic reaction. Catechin had both physical and chemical adsorption with the naked cast iron, and reacted with Fe³⁺ to form black amorphous ferric catechin which could effectively inhibit the corrosion in NaCl solution. Catechin reacted with the unstable γ-FeOOH in the rust layer, consuming and transforming into black amorphous product depositing in the rust layer. The product could make the original rust layer denser, with the ability to block the transfer of charges and ions more effectively between rusted cast iron and corrosive solution, and enhanced the protective effect of the internal metal. Catechin can be used as a natural corrosion inhibitor and stabilizer in the protection of ancient iron cultural heritage, and its application prospects will be broad.