Nuclear Science and Techniques

《核技术》(英文版) ISSN 1001-8042 CN 31-1559/TL     2018 Impact factor 0.961

Nuclear Science and Techniques ›› 2019, Vol. 30 ›› Issue (11): 165 doi: 10.1007/s41365-019-0693-0

• NUCLEAR ENERGY SCIENCE AND ENGINEERING • Previous Articles     Next Articles

Experimental Study on the Oxidation Behavior and Microstructure Evolution of Nuclear Graphite NG-CT-10 and NG-CT-20

Wei Lu1 • Ming-Yang Li2,3 • Xiao-Wei Li1 • Xin-Xin Wu1 • Li-Bin Sun1 • Zheng-Cao Li2   

  1. 1 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, Tsinghua University, Beijing 100084, China
    2 State Key Laboratory of New Ceramics and Fine Processing, Key Laboratory of Advance Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
    3 Department of Engineering Physics, Tsinghua University, Beijing 100084, China
  • Received:2019-02-01 Revised:2019-05-06 Accepted:2019-06-22
  • Contact: Xiao-Wei Li E-mail:lixiaowei@tsinghua.edu.cn
  • Supported by:
    This work was financially supported by the National Natural Science Foundation of China (No. 51576103) and the National S&T Major Project (No. ZX06901).
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Wei Lu, Ming-Yang Li, Xiao-Wei Li, Xin-Xin Wu, Li-Bin Sun, Zheng-Cao Li. Experimental Study on the Oxidation Behavior and Microstructure Evolution of Nuclear Graphite NG-CT-10 and NG-CT-20.Nuclear Science and Techniques, 2019, 30(11): 165     doi: 10.1007/s41365-019-0693-0

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 ℃ and that of NG-CT-20 is 153.5 kJ/mol in a temperature range of 550-650 ℃. 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.

Key words: Nuclear graphite, Oxidation, NG-CT-10, NG-CT-20, Activation energy