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

  • Wei Lu
  • Ming-Yang Li
  • Xiao-Wei LiEmail author
  • Xin-Xin Wu
  • Li-Bin Sun
  • Zheng-Cao LiEmail author
Article
  • 24 Downloads

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.

Keywords

Nuclear graphite Oxidation NG-CT-10 NG-CT-20 Activation energy 

References

  1. 1.
    Z. Zhang, Z. Wu, D. Wang et al., Current status and technical description of Chinese 2 × 250 MWth HTR-PM demonstration plant. Nucl. Eng. Des. 239, 1212–1219 (2009).  https://doi.org/10.1016/j.nucengdes.2009.02.023 CrossRefGoogle Scholar
  2. 2.
    Z. Zhang, Y. Dong, F. Li et al., The Shandong shidao bay 200 MWe high-temperature gas-cooled reactor pebble-bed module (HTR-PM) demonstration power plant: an engineering and technological innovation. Engineering 2, 112–118 (2016).  https://doi.org/10.1016/J.ENG.2016.01.020 CrossRefGoogle Scholar
  3. 3.
    Z. Zhang, Y. Dong, W. Scherer, Assessments of water ingress accidents in modular high temperature gas cooled reactor. Nucl. Technol. 149, 253–264 (2005)CrossRefGoogle Scholar
  4. 4.
    C.I. Contescu, T. Guldan, P. Wang et al., The effect of microstructure on air oxidation resistance of nuclear graphite. Carbon 50, 3354–3366 (2012).  https://doi.org/10.1016/j.carbon.2012.01.040 CrossRefGoogle Scholar
  5. 5.
    P. Wang, C.I. Contescu, S. Yu et al., Pore structure development in oxidized IG-110 nuclear graphite. J. Nucl. Mater. 430, 229–238 (2012).  https://doi.org/10.1016/j.jnucmat.2012.07.015 CrossRefGoogle Scholar
  6. 6.
    C. Karthik, J. Kane, D.P. Butt et al., Microstructural characterization of next generation nuclear graphites. Microsc. Microanal. 18, 272–278 (2012).  https://doi.org/10.1017/S1431927611012360 CrossRefGoogle Scholar
  7. 7.
    C. Zhang, Z. He, Y. Gao et al., The effect of molten FLiNaK salt infiltration on the strength of graphite. J. Nucl. Mater. 512, 37–45 (2018).  https://doi.org/10.1016/j.jnucmat.2018.09.051 CrossRefGoogle Scholar
  8. 8.
    S. Jing, C. Zhang, J. Pu et al., 3D microstructures of nuclear graphite: IG-110, NBG-18 and NG-CT-10. Nucl. Sci. Tech. 27, 66 (2016).  https://doi.org/10.1007/s41365-016-0071-0 CrossRefGoogle Scholar
  9. 9.
    H. Tang, W. Qi, Z. He et al., Infiltration of graphite by molten 2LiF–BeF 2 salt. J. Mater. Sci. 52, 11346–11359 (2017).  https://doi.org/10.1007/s10853-017-1310-4 CrossRefGoogle Scholar
  10. 10.
    C. Zhang, H. Tang, Z.He et al., Dataset on the mechanical property of graphite after molten FLiNaK salt infiltration. Data Brief 21, 1963–1969 (2018).  https://doi.org/10.1016/j.dib.2018.11.036 CrossRefGoogle Scholar
  11. 11.
    T. Shibata, J. Sumita, T. Tada et al., Non-destructive evaluation methods for degradation of IG-110 and IG-430 graphite. J. Nucl. Mater. 381, 165–170 (2008).  https://doi.org/10.1016/j.jnucmat.2008.07.014 CrossRefGoogle Scholar
  12. 12.
    P.A. Thrower, G.K. Mathew, N.J. Mcginnis, The influence of oxidation on the structure and strength of graphite II: materials of different impurity content. Carbon 20, 457–464 (1982).  https://doi.org/10.1016/0008-6223(82)90081-1 CrossRefGoogle Scholar
  13. 13.
    D.W. McKee, Metal oxides as catalysts for the oxidation of graphite. Carbon 8, 623–635 (1970).  https://doi.org/10.1016/0008-6223(70)90055-2 CrossRefGoogle Scholar
  14. 14.
    T. Miyatani, H. Suzuki, O. Yoshimoto, Quantitative analysis of trace amounts of impurities contaminating pure graphite with ICP-MS and metal atomizer FLAAS. No. IAEA-TECDOC-690 (1993)Google Scholar
  15. 15.
    H.K. Hinssen, K. Kühn, R. Moormann et al., Oxidation experiments and theoretical examinations on graphite materials relevant for the PBMR. Nucl. Eng. Des. 238, 3018–3025 (2008).  https://doi.org/10.1016/j.nucengdes.2008.02.013 CrossRefGoogle Scholar
  16. 16.
    E.L. Fuller, J.M. Okoh, Kinetics and mechanisms of the reaction of air with nuclear grade graphites: IG-110. J. Nucl. Mater. 240, 241–250 (1997).  https://doi.org/10.1016/s0022-3115(96)00462-x CrossRefGoogle Scholar
  17. 17.
    E.S. Kim, C.H. Oh, C.H. No, Experimental study and model development on the moisture effect for nuclear graphite oxidation. Nucl. Technol. 164, 278–285 (2008).  https://doi.org/10.13182/NT08-A4026 CrossRefGoogle Scholar
  18. 18.
    X. Luo, J.C. Robin, S. Yu, Effect of temperature on graphite oxidation behavior. Nucl. Eng. Des. 227, 273–280 (2004).  https://doi.org/10.1016/j.nucengdes.2003.11.004 CrossRefGoogle Scholar
  19. 19.
    S.H. Chi, G.C. Kim, Comparison of the oxidation rate and degree of graphitization of selected IG and NBG nuclear graphite grades. J. Nucl. Mater. 381, 9–14 (2008).  https://doi.org/10.1016/j.jnucmat.2008.07.027 CrossRefGoogle Scholar
  20. 20.
    H.C. Yang, H.C. Eun, D.G. Lee et al., Analysis of combustion kinetics of powdered nuclear graphite by using a non-isothermal thermogravimetric method. J. Nucl. Sci. Technol. 43, 1436–1439 (2006).  https://doi.org/10.1080/18811248.2006.9711238 CrossRefGoogle Scholar
  21. 21.
    P. Wang, S. Yu, Effects of gas flow rate and temperature on the oxidation rate of IG-110 nuclear graphite. J. Tsinghua Univ. (Sci. Tech.) 52, 504–547 (2012).  https://doi.org/10.16511/j.cnki.qhdxxb.2012.04.032 CrossRefGoogle Scholar
  22. 22.
    X. Luo, J.C. Robin, S. Yu, Comparison of oxidation behaviors of different grades of nuclear graphite. Nucl. Sci. Eng. 151, 121–127 (2005).  https://doi.org/10.13182/NSE05-A2534 CrossRefGoogle Scholar
  23. 23.
    D. Chen, Z. Li, M. Wei et al., Effects of porosity and temperature on oxidation behavior in air of selected nuclear graphites. Mater. Trans. 53, 1159–1163 (2012).  https://doi.org/10.2320/matertrans.MBW201107 CrossRefGoogle Scholar
  24. 24.
    X. Sun, Y. Dong, Y. Zhou et al., Effects of reaction temperature and inlet oxidizing gas flow rate on IG-110 graphite oxidation used in HTR-PM. J. Nucl. Sci. Technol. 54, 196–204 (2016).  https://doi.org/10.1080/00223131.2016.1233080 CrossRefGoogle Scholar
  25. 25.
    Z. Hu, Z. Li, D. Chen et al., CO2 corrosion of IG-110 nuclear graphite studied by gas chromatography. J. Nucl. Sci. Technol. 51, 487–492 (2014).  https://doi.org/10.1080/00223131.2013.877407 CrossRefGoogle Scholar
  26. 26.
    S.H. Chi, G.C. Kim, Effects of air flow rate on the oxidation of NBG-18 and NBG-25 nuclear graphite. J. Nucl. Mater. 491, 37–42 (2017).  https://doi.org/10.1016/j.jnucmat.2017.04.032 CrossRefGoogle Scholar
  27. 27.
    I. Childres, L. Jauregui, W. Park et al., Raman spectroscopy of graphene and related materials. New Dev. Photon Mater. Res. 1, 1–20 (2013).CrossRefGoogle Scholar
  28. 28.
    A. Maslova, M.R. Ammar, G. Guimbretière et al., Determination of crystallite size in polished graphitized carbon by Raman spectroscopy. Phys. Rev. B 86, 134205 (2012).  https://doi.org/10.1103/physrevb.86.134205 CrossRefGoogle Scholar
  29. 29.
    F. Tuinstra, J.L. Koenig, Raman spectrum of graphite. J. Chem. Phys. 53, 1126 (1970).  https://doi.org/10.1063/1.1674108 CrossRefGoogle Scholar
  30. 30.
    K.Y. Wen, T.J. Marrow, B.J. Marsden, The microstructure of nuclear graphite binders. Carbon 46, 62–71 (2008).  https://doi.org/10.1016/j.carbon.2007.10.025 CrossRefGoogle Scholar

Copyright information

© China Science Publishing & Media Ltd. (Science Press), Shanghai Institute of Applied Physics, the Chinese Academy of Sciences, Chinese Nuclear Society and Springer Nature Singapore Pte Ltd. 2019

Authors and Affiliations

  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 TechnologyTsinghua UniversityBeijingChina
  2. 2.State Key Laboratory of New Ceramics and Fine Processing, Key Laboratory of Advance Materials (MOE), School of Materials Science and EngineeringTsinghua UniversityBeijingChina
  3. 3.Department of Engineering PhysicsTsinghua UniversityBeijingChina

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