Chemical States in Oxide Films on Stainless Steel Treated in Supercritical Water Factor Analysis of X-Ray Photoelectron Spectra

A preliminary study of the corrosion films of stainless steel SUS304 was carried out by X-ray photoemission spectroscopy for supercritical water having no oxidant or reactant. The corrosion films produced by the supercritical water at 450DGC and 50 MPa were compared with those by anodic polarization...

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Bibliographic Details
Published in:Journal of the Electrochemical Society 2005-01, Vol.152 (12), p.B540-B546
Main Authors: Yamamura, Tomoo, Okuyama, Naoki, Shiokawa, Yoshinobu, Oku, Masaoki, Tomiyasu, Hiroshi, Sugiyama, Wataru
Format: Article
Language:English
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Summary:A preliminary study of the corrosion films of stainless steel SUS304 was carried out by X-ray photoemission spectroscopy for supercritical water having no oxidant or reactant. The corrosion films produced by the supercritical water at 450DGC and 50 MPa were compared with those by anodic polarization in H2SO4 aqueous solution. The chemical states in the films were determined by factor analysis of Fe, Cr, and Ni 2p X-ray photoelectron spectra. Factor analysis of the passivated SUS304 surface was successfully carried out using four reference spectra, Fe metal, Fe3O4, Fe2O3, and FeOOH, with careful treatment excluding wustite Fe1-xO phase from the standpoint of thermochemistry. In the surface treated by supercritical water, the ratio of iron and nickel increased even when compared to the bulk composition of SUS304 and the major component of nickel was attributed to NiFe2O4. In contrast, the content of chromium decreased remarkably. This was explained by effective removal of CrO2-4 and its protonated form, HCrO4, which are predicted in the Pourbaix diagram prepared for chromium in supercritical water (450DGC and 50 MPa).
ISSN:0013-4651
DOI:10.1149/1.2098347