Multilayer Corrosion of Aluminum Activated by Lead

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Title: Multilayer Corrosion of Aluminum Activated by Lead
Creators: Anawati; Graver, Brit; Nordmark, Heidi; Zhao, Zhijun; Frankel, G. S.; Walmsley, John Charles; Nisancioglu, Kemal
Issue Date: 2010-08-17
Publisher: The Electrochemical Society
Citation: Anawati et al, "Multilayer Corrosion of Aluminum Activated by Lead," Journal of the Electrochemical Society 157, no. 10 (2010), doi:10.1149/1.3478663
DOI: 10.1149/1.3478663
Abstract: Segregation of Pb as a nanofilm between the thermal oxide and the metal substrate as a result of high temperature heat-treatment is known to activate aluminum alloys anodically in chloride solution. The relationship between the oxidation peaks in the polarization curve and corrosion morphology was investigated by the use of a video technique during electrochemical polarization. A model binary Al–Pb alloy containing 20 ppm Pb, which was annealed at 600°C, showed two oxidation peaks at −0.95 and −0.88 V_SCE. The video measurements revealed superficial etching of the surface by selective oxidation of the aluminum metal twice, followed each time by repassivation, as the two oxidation peaks were resolved during anodic potentiodynamic sweep. Ex situ scanning and transmission electron microscopy of the corroded specimens indicated that the first layer of etching followed the Pb film and undermined the thermal oxide, which remained attached to the metal surface at discrete locations, thereby forming a crevice. The second layer of attack was caused by crevice corrosion of the aluminum substrate in the crevice formed by the preceding oxidation process, which resulted in the removal of the attached thermal oxide film. The exposed aluminum substrate started to pit as the pitting potential was finally exceeded.
ISSN: 1945-7111
Rights: © The Electrochemical Society, Inc. 2010. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published in Journal of The Electrochemical Society, 157 (10) C313-C320.
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