Role of Self-Assembled Monolayer of 1,2,3-Benzotriazole in Protecting Copper Artifacts Covered with Sulfide Film

Corrosion inhibition of the self-assembled monolayer (SAM) of 1,2,3-Benzotriazole (BTAH) on virgin and sulfide-covered (tarnished) copper surfaces was studied using impedance, scanning electron microscopy, and Raman spectroscopy. SAM on preexisting sulfide film develops a more improved protection than on the virgin surface. Addition of HS- ions and nonionic surface active agents (NIS) in SAM-forming solution deteriorate its properties. Raman spectroscopy established formation of polymeric film by adsorption of triazolate ion rather than triazole molecule. A scheme is suggested for improved inhibition of SAM on tarnished copper. Studies indicate a predominant cathodic control of corrosion reaction by the SAM film.