In situ surface enhanced Raman spectroscopic study on the effect of dissolved oxygen on the corrosion film on low carbon steel in 0.01 M NaCl solution

Citation
Wc. Baek et al., In situ surface enhanced Raman spectroscopic study on the effect of dissolved oxygen on the corrosion film on low carbon steel in 0.01 M NaCl solution, ELECTR ACT, 46(15), 2001, pp. 2321-2325
Citations number
30
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
ELECTROCHIMICA ACTA
ISSN journal
00134686 → ACNP
Volume
46
Issue
15
Year of publication
2001
Pages
2321 - 2325
Database
ISI
SICI code
0013-4686(20010430)46:15<2321:ISSERS>2.0.ZU;2-M
Abstract
In situ surface enhanced Raman spectroscopy was employed to study the effec t of dissolved oxygen (DO) an the composition of the corrosion film formed on a low carbon steel surface in 0.01 M NaCl solution. Raman spectra were t aken during cyclic voltammetric and potential step experiments. The spectra taken during cyclic voltammetry were similar to those previously obtained for passive iron. It showed a peak for a trivalent species at 670 cm(-1) in the passive potential range, which was usually assigned to FeOOH rather th an to gamma -Fe2O3. However, in the spectra taken during potential step exp eriments, it was apparent that the main trivalent species in the corrosion film was gamma -Fe2O3 at 640, 670, 715 cm(-1), and DO behaved as an oxidize r to convert iron from the divalent stair in Fe3O4 to the trivalent state ( gamma -Fe2O3). The presence of gamma -Fe2O3 in the corrosion film on iron w as detected for the first time bq taking SER spectra during potential step experiments. Though this film showed a weak protective property, and had co rrosion products due to pitting induced by chloride ions, the detection of gamma -Fe2O3 supports the previous ex situ and in situ findings that the tr ivalent oxide in iron passivity is gamma -Fe2O3. (C) 2001 Elsevier Science Ltd. All rights reserved.