ISSN 2305-6894

Cathodic behavior of pure Al in sulfate media

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1 Laboratoire de l’Eau et de l’Environnement, Faculté des Sciences d’El Jadida, BP 20, 24000 El Jadida, Morocco
2 Laboratoire Interface Matériaux et Environnement, Faculté des Sciences AïnChock, BP 5366 Maârif, Casablanca, Morocco
3 Sorbonne Université, CNRS, Laboratoire Interfaces et Systèmes Electrochimiques, 4 place Jussieu, F-75005, Paris, France
4 Kendig Research Associates LLC, 496 Hillsborough, Thousand Oaks, CA 91361, USA

Abstract: The cathodic behavior of Al in 0.5 M Na2SO4 solution was studied by electrochemical methods. It was shown that the reduction of Fe(CN)63- was difficult when an oxide layer was formed on the electrode surface during 1 h immersion in 0.5 M Na2SO4 solution due to the poor ionic and electronic conductivities of Al hydroxides. This reaction required a high cathodic overpotential on Al surface pre-treated at –2 V/SCE Al and was kinetically more difficult in comparison to platinum. Rotating disk electrode measurements showed that oxygen reduction reaction (ORR) was controlled by kinetics on both Al pre-treated at –2 V/SCE and oxidized Al cathodic dissolution was controlled by the supply of OH ions through H2 evolution and by ORR on both oxidized Al electrode and the Al surface pre-treated at –2 V/SCE. Polarization curves obtained at different pH values showed that no dissolution behavior was observed at pH 5, whereas in neutral and alkaline solutions, OH ions production induced chemical dissolution of the hydroxide layer. In O2 supersaturated solution, it was shown that ORR kinetics were slightly favored.

Keywords: aluminum, oxide film, cathodic corrosion, sulfate solution, polarization curves

Int. J. Corros. Scale Inhib., , 8, no. 2, 385-410 PDF (1 283 K)
doi: 10.17675/2305-6894-2019-8-2-17

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