Corrosion Behavior of Composite Coatings Obtained by Electrolytic Codeposition of Copper with Al2O3 Nanoparticles

I. Zamblau, S. Varvara, C. Bulea and L. M. Muresan

Abstract
Composite coatings of copper incorporating Al2O3 nanoparticles electrodeposited on carbon steel were obtained and characterized. By using electrochemical methods such as open circuit potential (ocp) measurements, polarization curves and electrochemical impedance spectroscopy, the corrosion behavior of the Al2O3-copper nanocomposite coatings was examined. The corrosion parameters determined from the polarization curves recorded in Na2SO4 solution (pH 3) indicate that the corrosion process on copper-Al2O3 composite surface is slower than on pure copper. The impedance spectra recorded at the ocp showed in all cases an increase of the polarization resistance in time, which may be explained by the development of corrosion products on the electrode surface. Using a (2RC) equivalent electrical circuit, the process parameters were estimated by non-linear regression calculations with a Simplex method. The Al2O3 particles embedded in the electroplated copper, increase the polarization resistance and decrease the corrosion rates as compared with electrodeposited pure copper. The electrochemical results were corroborated with those obtained by SEM and EDX investigations.

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Keywords
corrosion, electrolytic codeposition, copper composite coating, Al2O3 nanoparticles, Electrochemical Impedance Spectroscopy, SEM-EDX