Acta Metallurgica Sinica (English Letters) ›› 2022, Vol. 35 ›› Issue (6): 1011-1022.DOI: 10.1007/s40195-021-01278-2

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Influence of Deteriorated Bentonite Sediments on the Corrosion Behavior of NiCu Low Alloy Steel

Xin Wei1, Junhua Dong1(), Yupeng Sun1,3, Nan Chen1, Qiying Ren1, Madhusudan Dhakal1,3, Xiaofang Li1, Wei Ke2   

  1. 1Shenyang National Laboratory for Materials Science,Institute of Metal Research, Chinese Academy of Sciences,Shenyang 110016, China
    2Environmental Corrosion Centre of Materials, Institute of Metal Research, Chinese Academy of Sciences,Shenyang 110016, China
    3School of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China
  • Received:2021-03-23 Revised:2021-05-04 Accepted:2021-05-27 Online:2022-06-10 Published:2022-06-15
  • Contact: Junhua Dong
  • About author:Junhua Dong, jhdong@imr.ac.cn

Abstract:

The corrosion evolution of steel disposal container largely depends on the evolution of surrounding bentonite environment in the long-term geological disposal of high-level radioactive wastes. This study focused on the influence of the deteriorated bentonite sediments on the corrosion behavior of NiCu low alloy steel in the top supernatant and bottom slurry formed by Gaomiaozi bentonite and 0.05 M NaHCO3 + 0.1 M NaCl + 0.1 M Na2SO4 solution. In the top supernatant, the cathodic process of the steel corrosion was transformed from the reduction in oxygen to the reduction in ferric corrosion products with time as same as that in the blank solution. While in the bottom bentonite slurry, the cathodic process always maintained as the hydrogen evolution reaction due to the coverage of more bentonite sediments. Meanwhile, the corrosion rate of NiCu steel was obviously decreased. In addition, the localized corrosion tendency of the steel could also be reduced by the large amount of deteriorated bentonite sediments.

Key words: Low alloy steel, Bentonite, Corrosion behavior, Corrosion products, Electrochemical impedance spectroscopy (EIS)