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In situ study of gas transport through Al(OH)3 gels during AC processing

par Hammons, Joshua A;Rayment, T;Tzedaki, Maria;Van Ingelgem, Yves;Ustarroz Troyano, Jon ;Vandendael, Isabelle;Hubin, Annick ;Terryn, Herman
Référence Electrochimica Acta, 70, page (10-18)
Publication Publié, 2012-05

Article révisé par les pairs

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Résumé :

In this work the nature of gas transport through different Al(OH)3 gels (smut) formed during the AC elec- trograining process is characterized. A new in situ approach that combines small angle X-ray scattering (SAXS) with the electrochemical response is used to show that gas transport through the smut is different with and without additives. We conclude that gas transport occurs, predominantly, through temporary passageways when no additives are used and through permanent pores with additives, indicating a dif- ference in the gel (smut) rheological properties in each case. Gas transport, through the smut, is therefore considered to be a phenomenon that depends on the electrolyte composition, which is expected to alter the gel properties. These changes in the gas transport away from the metal surface correlate with changes in the potential response of the system. The uniquely lower overpotential, associated with temporary pas- sageways results in an etched-like morphology, suggesting that the gas permeability of the surface gel is a factor that affects the final pit morphology.