Microelectrochemical Characterization of the Effect of Rare Earth Inhibitors on the Localized Corrosion of AA2024-T3
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Citation:Li, Jichao, Belinda Hurley, and Rudolph Buchheit. "Microelectrochemical Characterization of the Effect of Rare Earth Inhibitors on the Localized Corrosion of AA2024-T3." Journal of The Electrochemical Society 162, no. 10 (2015): C563-C571. https://doi.org/10.1149/2.0791510jes
The inhibition effect of three rare earth metals (REMs), Ce3+, La3+ and Pr3+, on the electrochemical properties of synthesized single-phase intermetallic compounds (IMCs) representing phases commonly found in AA2024-T3 were studied and compared with chromate inhibition. REM additions had little effect on corrosion potential, pitting potential and icorr in short-term tests. This is in contrast to effects observed with chromate inhibitor additions where the pitting potential was seen to increase dramatically. All three REMs decreased the oxygen reduction reaction (ORR) kinetics on each synthesized phase, but none as much as chromate. The results in these studies are consistent with the idea that inhibition by REMs results from hydroxide precipitation at IMCs due to a local pH increase associated with the ORR. As hydroxide precipitation is a comparatively slow process, REMs cannot inhibit the initial dealloying of S phase, leading to the formation of dealloyed layers under hydroxide layers. Once the hydroxide precipitate forms, the subsequent corrosion of S phase is strongly inhibited. The dependence of inhibition on the formation of hydroxide deposits demonstrates that REMs are "slow" inhibitors, which must be considered in their applications.
This research is sponsored by the U.S. Air Force Academy under agreement number FA7000-12-2-0015. The U.S. Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright notation thereon. The views and conclusion contained herein are those of the authors and should not be interpreted as necessarily represented official policies or endorsement, either expressed or implied, of the U.S. Air Force Academy or the U.S. Government.
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Rights:© The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0791510jes] All rights reserved.
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