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Characterization of surface composition on Alloy 22 in neutral chloride solutions
Author(s) -
Zagidulin Dmitrij,
Zhang Xiangrong,
Zhou Jigang,
Noël James J.,
Shoesmith David W.
Publication year - 2013
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.5204
Subject(s) - oxide , alloy , x ray photoelectron spectroscopy , hydroxide , dielectric spectroscopy , chloride , corrosion , secondary ion mass spectrometry , layer (electronics) , chemistry , analytical chemistry (journal) , electrochemistry , passivity , inorganic chemistry , ion , materials science , chemical engineering , metallurgy , electrode , chromatography , electrical engineering , organic chemistry , engineering
The composition of anodically grown oxide films on Alloy 22, a Ni‐Cr‐Mo(W) alloy, has been investigated in 5 mol l −1 NaCl at room temperature using X‐ray photoelectron spectroscopy and time‐of‐flight secondary ion mass spectrometry. For applied potentials up to 0.2 V (vs Ag/AgCl (saturated KCl solution)), a Cr(III) oxide barrier layer develops at the alloy/oxide interface accounting for the excellent passivity demonstrated to prevail in this potential region by previous electrochemical impedance spectroscopy measurements. At higher potentials, this layer is destroyed by defect injection as Cr(III) is oxidized to the more soluble Cr(VI). The overall oxide/hydroxide film thickness is, however, increased as Mo(VI)/W(VI) species accumulate at the oxide solution interface. The potential of 0.2 V at which the barrier layer switches from growth to destruction coincides with the previously demonstrated threshold potential for the initiation of crevice corrosion. Copyright © 2012 John Wiley & Sons, Ltd.