Corrosion Mechanism of Low-Alloyed Steel in High-Temperature Water: Effect of Additives and Time of Exposure

Konsta Sipilä, Martin Bojinov (Corresponding Author), Wolfgang Mayinger, Timo Saario, Maxim Selektorc

    Research output: Contribution to journalArticleScientificpeer-review

    5 Citations (Scopus)


    The present paper investigates the effect of exposure time, chloride and sulfate additions on the corrosion mechanism of low-alloyed steel in a cladding flaw of a nuclear reactor pressure vessel using in-situ electrochemical impedance spectroscopy coupled to exsitu characterization of the oxides by surface analytical techniques. A quantitative interpretation of impedance spectra using the Mixed-Conduction Model for oxide films formed in high-temperature water allows for a discrimination between the rates of inner layer formation and cation transmission through that layer. The values of the inner layer thickness and cation release estimated from impedance measurements are in good agreement with those stemming from ex-situ analysis. At short exposure times, higher film formation and cation release rates of LAS are measured in the presence of chloride and sulfate additives. However, the effect of exposure time itself appears to be stronger than that of the impurities, and the protective ability of the oxides at longer exposure times starts to dominate the overall corrosion process.
    Original languageEnglish
    Pages (from-to)C530-C538
    JournalJournal of the Electrochemical Society
    Issue number9
    Publication statusPublished - 2016
    MoE publication typeA1 Journal article-refereed


    • chloride and sulfate impurities
    • high-temperature water
    • impedance spectroscopy
    • kinetic model
    • low-alloyed steel


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