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2019 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 324, article id UNSP 134847Article in journal (Refereed) Published
Abstract [en]
This work is a further step to develop a finite element model to simulate localized corrosion of aluminum alloys driven by micro-galvanic effects. The focus herein is to explore the effect of density (porosity and tortuosity) of Al(OH)(3) precipitates generated both on the electrode surface and in the liquid phase. Two coupled processes are identified and discussed, both influencing the local pH: the Al3+ dissolution from the electrode surface, and the steric hindrance effects on mass transport of species between the bulk solution and the anolyte next to the corroding surface. With the densest precipitate investigated, Al3+ dissolution is more effectively blocked and the mass transport largely hindered of Al3+ ions leaving the electrode surface. With increasing porosity of the precipitate, Al3+ dissolution is enhanced, also the mass transport of species in the electrolyte. The most severe localized acidification inside the occluded volume occurs when the density, namely ascribed by porosity, of precipitate is at an intermediate level with epsilon(c )= 0.01. In qualitative agreement with experimental observations, this work highlights the importance of corrosion product density on the progress of localized corrosion.
Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2019
Keywords
FEM model, Micro-galvanic corrosion, Al(OH)(3) precipitate, Porosity and tortuosity, Steric hindrance effect
National Category
Corrosion Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-262932 (URN)10.1016/j.electacta.2019.134847 (DOI)000489840900046 ()2-s2.0-85072305820 (Scopus ID)
Note
QC 20191030
2019-10-302019-10-302019-12-03Bibliographically approved