Electrochemical impedance spectroscopy of anodic processes on cobalt disilicide in sulfuric acid solutions

The frequency dependences of the impedance of a CoSi2 electrode in solutions of 0.5 M H2 SO4 and 0.05 M H2 SO4+ 0.45 M Na2 SO4 are measured in the range of potentials of the active-passive transition, passive state, and transpassive state. Impedance spectra are described using an equivalent circuit...

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Bibliographic Details
Published in:Protection of metals and physical chemistry of surfaces, Vol. 47, No. 2 (2011), p. 272-278
Main Author: Kichigin, I.
Other Involved Persons: Shein, B.
Format: electronic Article
Language:English
ISSN:2070-206X
Item Description:Original Russian Text © V.I. Kichigin, A.B. Shein, 2011, published in Fizikokhimiya Poverkhnosti i Zashchita Materialov, 2011, Vol. 47, No. 2, pp. 218–224.
Physical Description:Online-Ressource
DOI:10.1134/S2070205111020092
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  • The frequency dependences of the impedance of a CoSi2 electrode in solutions of 0.5 M H2 SO4 and 0.05 M H2 SO4+ 0.45 M Na2 SO4 are measured in the range of potentials of the active-passive transition, passive state, and transpassive state. Impedance spectra are described using an equivalent circuit with regard to the presence of an oxide layer on the electrode surface. The dependence of equivalent circuit parameters and time constants on the electrode potential is analyzed. It is found that the high anodic stability of cobalt disilicide in sulfuric acid solutions is due to the barrier properties of the oxide film. The variations in the thickness of the oxide layer with increasing electrode potential in the range of passive dissolution are estimated. It is revealed that the time constant related to the oxide layer increases before the transpassive transition.