Corrosion Monitoring Effect of Rhodamine-Ethylenediamine on Copper Relics under a Protective Coating.

Fluorescence spectroscopy is a common technique used to monitor early metallic corrosion. The fluorescence response characteristics of rhodamine-ethylenediamine toward Cu have been studied using fluorescence and infrared spectroscopy. Fluorescence microscopy and electrochemical impedance spectroscopy were used to study the monitoring effect of rhodamine-ethylenediamine on the corrosion of copper relics protected by an epoxy coating. The results showed a strong fluorescent response and selectivity toward Cu that existed using rhodamine-ethylenediamine. Early metallic corrosion of copper relics can be effectively monitored upon adding 0.8 wt % rhodamine-ethylenediamine to an epoxy coating. When the soaking time was increased, the fluorescence intensity of the fluorescent area on the coating became stronger. In addition, the area of the luminous coating reached ∼0.06 mm and the area of corrosion under the protective coating was ∼0.008 mm, which was about 1/10 of the fluorescence area observed on the coating.