Electrochemical & optical characterisation of passive films on stainless steels

The formation and breakdown of the passive film are mainly controlled by ionic and electronic transport processes; processes that are in turn controlled by the electronic properties of the film. Consequently a comprehensive understanding of mechanisms behind passivity and localised corrosion require...

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Bibliographic Details
Published in:Journal of physics. Conference series 2006-01, Vol.28 (1), p.74-78
Main Authors: Sudesh, T L, Wijesinghe, L, Blackwood, D J
Format: Article
Language:English
Subjects:
Austenitic stainless steels
Chromium
Electron transport
Iron
Localized corrosion
Optical properties
Photoelectric effect
Physics
Raman spectroscopy
Semiconductivity
Spectrum analysis
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Summary:The formation and breakdown of the passive film are mainly controlled by ionic and electronic transport processes; processes that are in turn controlled by the electronic properties of the film. Consequently a comprehensive understanding of mechanisms behind passivity and localised corrosion require a detailed perception of the electronic properties of the passive films together with compositional and structural information. As a step towards this goal the passive film on austenitic stainless steel, AISI 316L, formed in borate solution was characterised by in situ Raman spectroscopy and photocurrent spectroscopy coupled with electrochemical measurements. The composition, structure and semiconductivity of the passive films depended on the potential; Fe rich n-type oxide and a Cr rich p-type oxide dominated at more positive potentials and more negative potentials respectively whilst n-type dual layered film formed at intermediate potentials. Analyses of the bandgap determined for these oxides suggested their structures to be Fe2O3 and a Fe-Cr spinel. This hypothesis was supported by the results of in situ Raman spectroscopy.
ISSN:1742-6596
1742-6588
1742-6596
DOI:10.1088/1742-6596/28/1/015