Conduction mechanism of the anodic film on chromium in acidic sulphate solutions

Martin Bojinov, Gunilla Fabricius, Timo Laitinen, Timo Saario, Göran Sundholm (Corresponding Author)

    Research output: Contribution to journalArticleScientificpeer-review

    57 Citations (Scopus)

    Abstract

    The passive state of Cr in 1 M sulphate solutions (pH 0 and 5) was studied with a combination of electrochemical techniques — impedance spectroscopy, photoelectrochemistry and dc resistance measurements by the contact electric resistance (CER) technique.
    Passive film growth was found to be associated with an exponential increase of the film resistance probably due to the simultaneous dehydration/oxidation of Cr(II) to Cr(III) via a solid state electrochemical reaction. A description of the steady state passive film as a thin insulator layer with small intrinsic conductivity was consistent with the experimental results. Polarization of Cr, on which a steady state film had been formed, to positive and negative potentials led to substantial increase of the conductivity of the film.
    These changes can be attributed to the generation of lower and higher valency Cr species in solid state electrochemical reactions: At low potentials lower valency species are formed in the first layers adjacent to the metal/film interface, while at high potentials higher-valency species are formed in the first layers adjacent to the film/electrolyte interface.
    At sufficiently high positive (or low negative) potentials the film was concluded to be transformed into a conductor allowing transpassive (or active) dissolution to take place.
    Original languageEnglish
    Pages (from-to)247-261
    JournalElectrochimica Acta
    Volume44
    Issue number2-3
    DOIs
    Publication statusPublished - 1998
    MoE publication typeA1 Journal article-refereed

    Fingerprint

    Chromium
    Sulfates
    Electric contacts
    Film growth
    Dehydration
    Electrolytes
    Dissolution
    Metals
    Spectroscopy
    Polarization
    Oxidation

    Cite this

    Bojinov, Martin ; Fabricius, Gunilla ; Laitinen, Timo ; Saario, Timo ; Sundholm, Göran. / Conduction mechanism of the anodic film on chromium in acidic sulphate solutions. In: Electrochimica Acta. 1998 ; Vol. 44, No. 2-3. pp. 247-261.
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    abstract = "The passive state of Cr in 1 M sulphate solutions (pH 0 and 5) was studied with a combination of electrochemical techniques — impedance spectroscopy, photoelectrochemistry and dc resistance measurements by the contact electric resistance (CER) technique. Passive film growth was found to be associated with an exponential increase of the film resistance probably due to the simultaneous dehydration/oxidation of Cr(II) to Cr(III) via a solid state electrochemical reaction. A description of the steady state passive film as a thin insulator layer with small intrinsic conductivity was consistent with the experimental results. Polarization of Cr, on which a steady state film had been formed, to positive and negative potentials led to substantial increase of the conductivity of the film. These changes can be attributed to the generation of lower and higher valency Cr species in solid state electrochemical reactions: At low potentials lower valency species are formed in the first layers adjacent to the metal/film interface, while at high potentials higher-valency species are formed in the first layers adjacent to the film/electrolyte interface. At sufficiently high positive (or low negative) potentials the film was concluded to be transformed into a conductor allowing transpassive (or active) dissolution to take place.",
    author = "Martin Bojinov and Gunilla Fabricius and Timo Laitinen and Timo Saario and G{\"o}ran Sundholm",
    year = "1998",
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    Conduction mechanism of the anodic film on chromium in acidic sulphate solutions. / Bojinov, Martin; Fabricius, Gunilla; Laitinen, Timo; Saario, Timo; Sundholm, Göran (Corresponding Author).

    In: Electrochimica Acta, Vol. 44, No. 2-3, 1998, p. 247-261.

    Research output: Contribution to journalArticleScientificpeer-review

    TY - JOUR

    T1 - Conduction mechanism of the anodic film on chromium in acidic sulphate solutions

    AU - Bojinov, Martin

    AU - Fabricius, Gunilla

    AU - Laitinen, Timo

    AU - Saario, Timo

    AU - Sundholm, Göran

    PY - 1998

    Y1 - 1998

    N2 - The passive state of Cr in 1 M sulphate solutions (pH 0 and 5) was studied with a combination of electrochemical techniques — impedance spectroscopy, photoelectrochemistry and dc resistance measurements by the contact electric resistance (CER) technique. Passive film growth was found to be associated with an exponential increase of the film resistance probably due to the simultaneous dehydration/oxidation of Cr(II) to Cr(III) via a solid state electrochemical reaction. A description of the steady state passive film as a thin insulator layer with small intrinsic conductivity was consistent with the experimental results. Polarization of Cr, on which a steady state film had been formed, to positive and negative potentials led to substantial increase of the conductivity of the film. These changes can be attributed to the generation of lower and higher valency Cr species in solid state electrochemical reactions: At low potentials lower valency species are formed in the first layers adjacent to the metal/film interface, while at high potentials higher-valency species are formed in the first layers adjacent to the film/electrolyte interface. At sufficiently high positive (or low negative) potentials the film was concluded to be transformed into a conductor allowing transpassive (or active) dissolution to take place.

    AB - The passive state of Cr in 1 M sulphate solutions (pH 0 and 5) was studied with a combination of electrochemical techniques — impedance spectroscopy, photoelectrochemistry and dc resistance measurements by the contact electric resistance (CER) technique. Passive film growth was found to be associated with an exponential increase of the film resistance probably due to the simultaneous dehydration/oxidation of Cr(II) to Cr(III) via a solid state electrochemical reaction. A description of the steady state passive film as a thin insulator layer with small intrinsic conductivity was consistent with the experimental results. Polarization of Cr, on which a steady state film had been formed, to positive and negative potentials led to substantial increase of the conductivity of the film. These changes can be attributed to the generation of lower and higher valency Cr species in solid state electrochemical reactions: At low potentials lower valency species are formed in the first layers adjacent to the metal/film interface, while at high potentials higher-valency species are formed in the first layers adjacent to the film/electrolyte interface. At sufficiently high positive (or low negative) potentials the film was concluded to be transformed into a conductor allowing transpassive (or active) dissolution to take place.

    U2 - 10.1016/S0013-4686(98)00169-8

    DO - 10.1016/S0013-4686(98)00169-8

    M3 - Article

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