STP1245

    On the Initial Corrosion Mechanism of Zirconium Alloy: Interaction of Oxygen and Water with Zircaloy at Room Temperature and 450°C Evaluated by X-Ray Absorption Spectroscopy and Photoelectron Spectroscopy

    Published: Jan 1994


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    Abstract

    The initial stages of zirconium oxide formation on Zircaloy after water (H2O) and oxygen (O2) exposures have been investigated in situ using photoelectron spectroscopy and X-ray-absorption spectroscopy. The reactivity of the zirconium alloy with O2 at room temperature is about 1000 times higher than for H2O. Up to 100 L (1 L = 1 Langmuir unit = 1 ∙ 10-6 mbar ∙ s) H2O exposure, the reactivity of the zirconium alloy at 450°C is comparable to the room temperature reaction. At higher H2O exposure, a sharp increase in the reaction rate for the high-temperature oxidation is observed. From the energy position of the Zr 3d photo emission line and their oxygen-induced chemical shifts, one can directly follow the formation of the oxide films. Two different substoichiometric oxides were found during reaction with water. Suboxide (1) is located at the zirconium/zirconium-oxide interface. Subsequently, a Suboxide (2) is concluded from the chemical shift of the zirconium photoelectrons. After an oxide thickness of 2 nm, the stoichiometric ZrO2 phase is not yet developed.

    Keywords:

    zirconium alloys, corrosion, water, oxygen reactivity, X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, corrosion mechanisms, zirconium, nuclear materials, nuclear applications


    Author Information:

    Döbler, U
    Sietec GmbH, Research Laboratory at BESSY, Berlin,

    Knop, A
    Sietec GmbH, Research Laboratory at BESSY, Berlin,

    Institut für Festkörperphysik, Berlin,

    Ruhmann, H
    Siemens AG, Power Generation Group (KWU), Erlangen,

    Beie, H-J
    Siemens AG, Corporate Research and Development, Erlangen,


    Paper ID: STP15213S

    Committee/Subcommittee: B10.02

    DOI: 10.1520/STP15213S


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