The formation of protective layers on copper, zinc and copper–zinc alloys at open circuit potential in aerated, near neutral NaCl solution containing benzotriazole was studied using electrochemical impedance and XPS spectroscopy. Benzotriazole (BTAH), generally known as an inhibitor of copper corrosion, also proved to be an efficient inhibitor for copper–zinc alloys and zinc metal. A tentative structural model describing the improved corrosion resistance of Cu, Cu–xZn alloys and Zn in BTAH containing chloride solution is proposed.
The inhibition of copper corrosion in 3% NaCl solution was studied by using a benzotriazole (BTAH) and 1-hydroxybenzotriazole (BTAOH) inhibitors. Experiments showed that BTAH is a more effective inhibitor of the corrosion than BTAOH. Simulations reveal that the two inhibitors display very simiar molecular electronic properties. Superior inhibition effectiveness of BTAH was attributed to interplay of planar molecular structure, adsorption and intermolecular bonding, which cooperatively may result in formation of thin and protective film on the surface.
The formation of protective layers on copper, zinc and copper–zinc alloys in chloride solution containing benzotriazole (BTAH) was investigated by electrochemical techniques, atomic force microscopy and XPS spectroscopy. The addition of benzotriazole to solution affects the dissolution of copper, zinc, and their alloys. Benzotriazole, generally known as an inhibitor of copper corrosion is also shown to be an efficient inhibitor for copper–zinc alloys and zinc metal. The surface layer formed on alloys in BTAH-inhibited solution comprised both metal-oxide and inhibitor-polymer components.
The interactions between chlorine and copper surface was studied by means of density functional theory simulations. The chemisorption energy of Cl is independent on the coverage up to the coverage of 1/3 ML due to a good screening of metal electrons. Upon further increase of coverage, its magnitude decreases. The diagram of the adsorption free energy as a function of chlorine chemical potential reveals that the on-surface (?3×?3)R30o adsorption phase is thermodynamically the most stable over a very broad range of Cl chemical potentials.
Molecular modeling was used to evaluate the structural, electronic and reactivity parameters of 1,2,4-triazoles and its amino derivatives in relation to their effectiveness as corrosion inhibitors. 3-amino derivatives with preferred corrosion inhibition performance possesses two electrophilic and two nucleophilic attack centers, implying multicenter adsorption of the molecule on a metal surface. Its interaction with the Cu atom is dominated by the electron donation from the Cu atom to the ring-carbon atom and the back-donation from the amino nitrogen atom.