Document Type

Article

Research Focus Area

Advanced and Nanostructured Materials

Publication Date

2008

Journal or Book Title

Journal of the Electrochemical Society

Volume

155

Issue

5

First Page

C189

Last Page

C195

DOI

10.1149/1.2883827

Abstract

The mechanism of anodic alkaline dissolution of aluminum was investigated through the analysis of cyclic voltammetry (CV) and potential step experiments. Attention was focused on the role of aluminum hydride as a reaction intermediate, as suggested by the recent detection of formation during open-circuit dissolution. Potential step experiments at pH 11.75 revealed that the potential at the metal–surface film interface was close to the Nernst potential of oxidation. This finding suggested a reaction mechanism in which an interfacial layer is formed continuously by reaction of cathodically formed H with Al, and is then oxidized to the dissolution product, aluminate ions. However, potential step experiments at pH 11 did not indicate the presence of interfacial ; instead, the metal–film interface was close to the equilibrium potential of Al oxidation. Analysis of the CV indicated an abrupt transition in dissolution behavior between the two pH values, from a relatively rapid dissolution controlled by diffusion and film conduction in highly alkaline solutions, to a slow dissolution at a lower pH controlled by a highly resistive surface film. The formation of interfacial occurs readily at the higher pH, but is suppressed as the pH approaches neutrality.

Comments

This article is from Journal of the Electrochemical Society 155 (2008): C189–C195, doi:10.1149/1.2883827. Posted with permission.

Copyright Owner

ECS—The Electrochemical Society

Language

en

File Format

application/pdf

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