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Kinetic Passivation Effect of Localized Differential Aeration on Brass
Author(s) -
Kuznetsov Volodymyr,
EstradaVargas Arturo,
Maljusch Artjom,
Berkes Balázs B.,
Bandarenka Aliaksandr S.,
Souto Ricardo M.,
Schuhmann Wolfgang
Publication year - 2016
Publication title -
chempluschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.801
H-Index - 61
ISSN - 2192-6506
DOI - 10.1002/cplu.201500398
Subject(s) - passivation , benzotriazole , aeration , corrosion , materials science , electrochemistry , layer (electronics) , brass , zinc , anode , galvanic anode , metallurgy , chemistry , inorganic chemistry , cathodic protection , chemical engineering , electrode , copper , composite material , organic chemistry , engineering
The formation of a localized differential aeration cell on metals, susceptible to both anodic and cathodic corrosion, is a serious threat because of multiple degradation processes commencing with the passivation layer destruction. By using local electrochemical and X‐ray dispersive techniques, it has been demonstrated that the differential aeration cell formed on high brass (α‐brass, Cu65‐Zn35) in the presence of 1 H ‐benzotriazole or 5‐methyl‐1 H ‐benzotriazole plays both corrosion‐inhibiting and accelerating roles, depending on the inhibitor exposure time. Alternating‐current scanning electrochemical microscopy was used to image local electrochemical activity, whereas energy‐dispersive X‐ray spectroscopy provided evidence for the mechanism of the observed phenomena. Short‐term exposure to the inhibitor (5 min) promotes the formation of a passivation layer in the waterline region. In contrast, after prolonged exposure (45 min), a deficient passivation layer develops for both inhibitors. An excess of zinc(II)–inhibitor complexes in the passivation layer is accountable for the corrosion resistance of the region with high differential aeration. Rapid dezincification and local alkalinization facilitate the initial rapid formation of a passivation layer in the area under differential aeration to preserve its composition upon further modification.