engleski

A Spectroelectrochemical Study of Complex Films Formed on Copper by Aqueous Benzotriazole

In spite of the fact that copper is a relatively noble metal, it reacts easily in oxygen-containing environments. In view of limited passivation offered by Cu-oxides, application of a corrosion inhibiting agent, such as 1 H-benzotriazole (I H-BTA) has been successfully used in prevention of Cu-corrosion. The mechanism of corrosion inhibition of copper by BTA in Na-acetate buffer solution pH=5.8 was established by relating interfacial structure obtained from photopolarisation and spectroscopic measurements to the corrosion reaction kinetics obtained from corrosion rate determinations. The corrosion rate of the sample was determined from AC and DC polarization resistance measurements at open circuit potential, as well as from cyclic voltammetry. A decrease of the corrosion rate in the presence of inhibitor was coupled with a change of: the double layer structure as result of adsorption, the electrode reactivity toward the strong chemibonding reaction between the electrode and the adsorbates, and the formation of the three-dimensional protective layer between the electrode surface and solution. The structure, stoichiometry, electric and dielectric properties of the Cu-BTA films were characterized using in-situ and ex-situ techniques. The film provides a complex multilayer structure. According to a combination of the results of Auger spectroscopy, photopolarisation, impedance spectroscopy and Raman spectroscopy, the inner part of the formed surface film consists predominantly of a cuprous oxide while the outer part is composed of the Cu(I)BTA. Capacity data indicated that the film thickness increased with time and the concentration and exhibited self-limited growth by a logarithmic law. The film grows kinetics is determined by the migration of Cu ions through the film, which is limited by the Cu-BTA barrier film.

copper; benzotriazole; protective film; Auger spectroscopy; photopolarisation; impedance spectroscopy; Raman spectroscopy

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