The electrochemical properties of alloy 690 in simulated pressurized water reactor primary water: Effect of temperature

JOURNAL OF NUCLEAR MATERIALS

卷:518

Article

Yang, Jie¹  Li, Yanhui^1,2  Xu, Aoni^1,3  Fekete, Balazs¹  Macdonald, Digby D.¹ 

[1] Univ Calif Berkeley, Dept Nucl Engn, Berkeley, CA 94720 USA

[2] Xi An Jiao Tong Univ, Sch Energy & Power Engn, Key Lab Thermofluid Sci & Engn, MOE, Xian 710049, Shanxi, Peoples R China

[3] Univ Sci & Technol Beijing, Corros & Protect Ctr, Key Lab Corros & Protect, MOE, Beijing 100083, Peoples R China

关键词: Alloy 690;    Passive film;    Anodic potentiostatic polarization;    EIS;    Optimization;   

DOI  :  10.1016/j.jnucmat.2019.03.016

来源: Elsevier

【 摘 要 】

By anodic potentiostatic polarization and electrochemical impedance spectroscopy (EIS) measurements, the effect of temperature (200 degrees C, 250 degrees C, and 300 degrees C) on the electrochemical behavior of Alloy 690 was investigated in oxygenated borate buffer solution containing H3BO3 (2000 ppm B) + LiOH (2 ppm Li). The steady state passive current density was independent of the film formation potential at each temperature, indicating that the passive film is n-type in electronic character based on the predictions of the Point Defect Model (PDM). The passive current density increased and the absolute value of impedance decreased with increasing temperature, indicating a corresponding decrease in corrosion resistance. A mixed potential model (MPM), containing the PDM for describing the anodic passive dissolution of the alloy and the generalized Butler-Volmer equation for the cathodic oxygen reduction reaction was optimized on the experimental EIS data in order to extract model parameters, including kinetic parameters for the generation and annihilation of point defects in the barrier layer of the passive film. Metal (Cr, Ni, Fe) interstitials, which were found to have a higher concentration than oxygen vacancies, dominate the point defect structure of the barrier layer of the passive film at each temperature, thereby accounting for the n-type behavior of the passive film. With increasing temperature, the film thickness and defect density also increased, resulting in the decreased corrosion resistance of film. This indicates that the defect density of passive film plays a more important role on corrosion behavior of alloy than the film thickness. (C) 2019 Elsevier B.V. All rights reserved.

【 授权许可】

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