engleski

Study of Copper Corrosion Protection by Organic Inhibitors

The aim of this work is to obtain a deeper insight into the mechanism of inhibiting action of three imidazole based corrosion inhibitors: 1-(p-tolyl)-4-methylimidazole, 1-(o-tolyl)-4-methylimidazole, and 1-phenyl-4-methylimidazole. Investigations have been performed on copper in 3% NaCl, by electrochemical impedance spectroscopy and electrochemical quartz crystal microbalance (EQCM). The kinetic changes of corrosion processes have been followed during 24 hours. By EQCM measurement, it was observed that the corrosion rate is not significantly changing with time. Studies performed in the presence of three imidazole based corrosion inhibitors have shown that, although these molecules have very similar structure, differences in their behavior can be observed. Two inhibitors that contain the tolyl substituent decrease the corrosion rate of copper due to the formation of thin layer of adsorbate, while in the case of 1-phenyl-4-methylimidazole, formation of thick layer can be followed with time. After few hours of the layer formation, change of corrosion potential was observed which was followed by the significant decrease of the adsorption rate. From EIS (Electrochemical Impedance Spectroscopy) studies, it was observed that all inhibitors efficiently protect copper, and that the degree of the protection is increasing with time. In the case of 1-phenyl-4-methylimidazole EIS data suggest that the structure of the protective layer is changing with time and that two different structures exist, one is an inner thin corrosion product layer and another is a much thicker outer layer with rougher structure constituted of inhibitor.

Equivalent circuit; EIS; EQCM; Imidazole; Surface film; Time dependence

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