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Experimental study on the oxidation behavior and microstructural evolution of NG-CT-10 and NG-CT-20 nuclear graphite

Authors
  • Lu, Wei1
  • Li, Ming-Yang2, 3
  • Li, Xiao-Wei1
  • Wu, Xin-Xin1
  • Sun, Li-Bin1
  • Li, Zheng-Cao2
  • 1 Tsinghua University, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Institute of Nuclear and New Energy Technology, Beijing, 100084, China , Beijing (China)
  • 2 Tsinghua University, State Key Laboratory of New Ceramics and Fine Processing, Key Laboratory of Advance Materials (MOE), School of Materials Science and Engineering, Beijing, 100084, China , Beijing (China)
  • 3 Tsinghua University, Department of Engineering Physics, Beijing, 100084, China , Beijing (China)
Type
Published Article
Journal
Nuclear Science and Techniques
Publisher
Springer-Verlag
Publication Date
Oct 23, 2019
Volume
30
Issue
11
Identifiers
DOI: 10.1007/s41365-019-0693-0
Source
Springer Nature
Keywords
License
Yellow

Abstract

NG-CT-10 and NG-CT-20 are newly developed grades of nuclear-grade graphite from China. In this study, their oxidation behaviors were experimentally investigated using thermal gravimetric analysis. Microstructural evolution before and after oxidation was investigated using scanning electron microscope, mercury intrusion, and Raman spectroscopy. The apparent activation energy of NG-CT-10 nuclear graphite is 161.4 kJ/mol in a reaction temperature range of 550–700 °C and that of NG-CT-20 is 153.5 kJ/mol in a temperature range of 550–650 °C. The activation energy in the inner diffusion control regime is approximately half that in the kinetics control regime. At high temperatures, the binder phase is preferentially oxidized over the filler particles and small pores are generated in the binder. No new large or deep pores are generated on the graphite surfaces. Oxygen can diffuse along the boundaries of filler particles and through the binder phase, but cannot diffuse into the spaces between the nanocrystallites in the filler particles. Filler particles are oxidized starting at their outer surfaces, and the sizes of nanocrystallites do not decrease following oxidation.

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