Scanning electrochemical microscopic observation of corrosion reactions on a duplex stainless steel

So Aoki, Tomomi Taniguchi, Jun'ichi Sakai

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    Abstract

    The objective of this study is to clarify the preferential dissolution mechanism of a duplex stainless steel (DSS) at its corrosion potential (about -0.15 V vs.SHE) by means of Scanning Electrochemical Microscope (SECM) observation of the corrosion reactions on the ferritic phase (α phase) and the austenitic phase (γ phase) of a DSS, respectively. Probe electrode was fixed above α and γ each phase of DSS at corrosion potential in 1 mol/l HCl aqueous solution. Potential of the probe electrode was polarized toward noble direction, from - 0.10 V to 1.4 V (SHE), at a potential scan rate of 20 mV/s, and probe current was measured. In a probe potential range of 0∼0.70 V (SHE), anodic current due to hydrogen oxidation reaction could be detected. This anodic current was larger above y phase than that above α phase. In a probe potential range of 0.70∼1.2 V (SHE), anodic current due to Fe2+ oxidation reaction to Fe3+ could be detected. This anodic current was larger above a phase than that above y phase. On the α phase, the anodic dissolution reaction occurred preferentially at the DSS corrosion potential, while on the γ phase, the cathodic reduction reaction of hydrogen ion occurred preferentially.

    Original languageEnglish
    Pages (from-to)414-420
    Number of pages7
    JournalZairyo to Kankyo/ Corrosion Engineering
    Volume64
    Issue number9
    Publication statusPublished - 2015

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    Keywords

    • Austenitic phase
    • Duplex stainless steel
    • Ferritic phase
    • Hydrogen evolution
    • Preferential dissolution
    • Scanning electrochemical microscope

    ASJC Scopus subject areas

    • Electrochemistry
    • Materials Chemistry
    • Metals and Alloys
    • Surfaces, Coatings and Films

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