Iron passivity in borate buffer: Formation of a deposit layer and its influence on the semiconducting properties

Journal Article · Sun Feb 01 04:00:00 EST 1998 · Journal of the Electrochemical Society

DOI:https://doi.org/10.1149/1.1838311· OSTI ID:599922

Buechler, M; Schmuki, P; Boehni, H ^[1]

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1. Swiss Federal Inst. of Tech., Zuerich (Switzerland). Inst. of Materials, Chemistry and Corrosion

The formation, growth, and dissolution of the passive film on iron in neutral and alkaline solutions was investigated using a light reflectance technique. It was found that depending on the hydrodynamic conditions the formation of a hydroxide layer can take place during passivation. The strong influence of the hydrodynamic conditions can explain many contradictory results in the literature concerning the presence of a hydroxide layer on the protecting oxide film. Furthermore, the hydroxide layer affects capacitance and photocurrent measurements which are frequently used to obtain information about the semiconducting properties of the passive film on iron. In photoelectrochemical experiments the incoming photon flux is attenuated by the hydroxide layer which results in a decrease of photocurrent intensity. In the ac-impedance measurements the potential dependence of the capacitance is qualitatively not affected, but a significantly increased frequency dispersion of the results is observed.

• Sponsoring Organization: USDOE
• OSTI ID: 599922
• Journal Information: Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 2 Vol. 145; ISSN JESOAN; ISSN 0013-4651
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BORATES
CAPACITANCE
DISSOLUTION
ELECTRICAL PROPERTIES
IRON
IRON HYDROXIDES
IRON OXIDES
PASSIVATION
PHOTOCURRENTS
PROTECTIVE COATINGS