熔盐堆用超细颗粒石墨结构和熔盐浸渗研究（英文）
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摘要
研究各向同性微细颗粒石墨ZXF-5Q的微结构及熔盐浸渗特性。使用光学显微镜、压汞仪、真密度仪、透射电子显微镜、X射线衍射仪以及拉曼光谱仪,对其气孔、煅烧裂纹、Mrozowski裂纹及晶体结构进行表征。结果表明,ZXF-5Q拥有均匀分布的气孔,非常小的入孔孔径(0.4μm),数量众多的透镜状Mrozowski裂纹以及良好的晶体结构。熔盐浸渗实验在不同压力(分别为1、3、5个大气压)650℃环境下进行。利用扫描电子显微镜和X射线能谱仪对其浸渗特性进行了观察分析。研究表明,由于其非常小的入口孔径,ZXF-5Q在5个大气压外加压强环境下依然可以很好阻止熔盐浸渗。尽管没有浸渗发生,在ZXF-5Q内部可以发现球形熔盐颗粒,可能是熔盐蒸汽凝结造成的。
The microstructure and molten salt impregnation characteristics of a micro-fine grain isotropic graphite ZXF-5Q from Poco Inc. was investigated. The microstructural characteristics of the pores caused by gas evolution,calcination cracks,Mrozowski cracks,and the crystal structure were characterized by optical microscopy,mercury porosimetry,helium pycnometry,transmission electron microscopy,X-ray diffraction and Raman spectroscopy. Results show that the ZXF-5Q has uniformly-distributed pores caused by gas evolution with very small entrance diameters( ~ 0. 4 μm),and numerous lenticular Mrozowski cracks. Molten salt impregnation with a molten eutectic fluoride salt at 650 ℃ and 1,3 and 5 atm,indicate that ZXF-5Q could not be infiltrated even at 5 atm due to its very small pore entrance diameter. Some scattered global salt particles found inside the ZXF-5Q are possibly formed by condensation of the fluoride salt steam during cooling.
The microstructure and molten salt impregnation characteristics of a micro-fine grain isotropic graphite ZXF-5Q from Poco Inc. was investigated. The microstructural characteristics of the pores caused by gas evolution,calcination cracks,Mrozowski cracks,and the crystal structure were characterized by optical microscopy,mercury porosimetry,helium pycnometry,transmission electron microscopy,X-ray diffraction and Raman spectroscopy. Results show that the ZXF-5Q has uniformly-distributed pores caused by gas evolution with very small entrance diameters( ~ 0. 4 μm),and numerous lenticular Mrozowski cracks. Molten salt impregnation with a molten eutectic fluoride salt at 650 ℃ and 1,3 and 5 atm,indicate that ZXF-5Q could not be infiltrated even at 5 atm due to its very small pore entrance diameter. Some scattered global salt particles found inside the ZXF-5Q are possibly formed by condensation of the fluoride salt steam during cooling.
引文
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[2]Burchell TD.Carbon Materials for Advanced Technologies[M].Pergamon,1999.
[3]Virgil'ev YS,Kalyagina IP.Reactor Graphite[M].Inorg Mater2003,39:S46-S58.
[4]Simmons JHW.Radiation Damage in Graphite[M].Pergamon Press,1965.
[5]Haag G,Reaktortechnik FJIf Su.Properties of ATR-2E Graphite and Property Changes Due to Fast Neutron Irradiation[M].Forschungszentrum Jülich Gmb H,Zentralbibliothek,2005.
[6]Telling RH,Heggie MI.Radiation defects in graphite[J].Philos Mag,2007,87(31):4797-4846.
[7]A technology roadmap for generation IV nuclear energy systems[R].USDOE,GIF-002-00,2002.
[8]Rosenthal MW,Haubenreich PN,Briggs RB.The development status of motten-salt dreeder reactor[R].ORNL-4812,1972.
[9]Briggs RB.Program semi annual progress report[R].MSRE,ORNL-3708,1964.
[10]Ketsten PR.Graphite behavior and its effects on MSBR perform[R].ORNL-TM-2136,1969.
[11]Mc Coy HE,Weir JR.Materials development for motten salts breeder reactor[R].ORNL-TM-1854,1967:46-56.
[12]Ishiyama S,Burchell TD,Strizak JP,et al.The effect of high fluence neutron irradiation on the properties of a fine-grained isotropic nuclear graphite[J].J Nucl Mater,1996,230(1):1-7.
[13]Burchell TD,Snead LL.The effect of neutron irradiation damage on the properties of grade NBG-10 graphite[J].J Nucl Mater,2007,371(1-3):18-27.
[14]Feng SL,Xu L,Li L,et al.Sealing nuclear graphite with pyrolytic carbon[J].J Nucl Mater,2013,441(1-3):449-454.
[15]He XJ,Song JL,Xu L,et al.Protection of nuclear graphite toward liquid fluoride salt by isotropic pyrolytic carbon coating[J].J Nucl Mater,2013,442(1-3):306-308.
[16]He XJ,Song JL,Tan J,et al.Si C coating:An alternative for the protection of nuclear graphite from liquid fluoride salt[J].J Nucl Mater,2014,448(1-3):1-3.
[17]Song JL,Zhao YL,Zhang JP,et al.Preparation of binderless nanopore-isotropic graphite for inhibiting the liquid fluoride salt and Xe135 penetration for molten salt nuclear reactor[J].Carbon,2014,79(0):36-45.
[18]Zhang BL,Xia HH,He XJ,et al.Characterization of the effects of 3-Me V proton irradiation on fine-grained isotropic nuclear graphite[J].Carbon,2014,77:311-318.
[19]Bernardet V,Gomes S,Delpeux S,et al.Protection of nuclear graphite toward fluoride molten salt by glassy carbon deposit[J].J Nucl Mater,2009,384(3):292-302.
[20]Wen KY,Marrow J,Marsden B.Microcracks in nuclear graphite and highly oriented pyrolytic graphite(HOPG)[J].J Nucl Mater,2008,381(1-2):199-203.
[21]Kane J,Karthik C,Butt DP,et al.Microstructural characterization and pore structure analysis of nuclear graphite[J].J Nucl Mater,2011,415(2):189-197.
[22]Mrozowski S.Anisotropy of thermal expansion and internal stresses in polycrystalline graphite and carbons[J].Physical Review,1952,86(4):622.
[23]Sutton AL,Howard VC.The role of porosity in the accommodation of thermal expansion in graphite[J].J Nucl Mater,1962,7(1):58-71.
[24]Chi S-H,Kim G-C.Comparison of 3 Me V C(+)ion-irradiation effects between the nuclear graphites made of pitch and petroleum cokes[J].J Nucl Mater,2008,381(1-2):98-105.
[25]Tuinstra F,Koenig JL.Raman spectrum of graphite[J].J Chem Phys,1970,53(3):1126-1130.
[26]Nikiel L,Jagodzinski PW.Raman-spectroscopic characterization of graphites-a reevaluation of spectra/structure correlation[J].Carbon,1993,31(8):1313-1317.
[27]Jawhari T,Roid A,Casado J.Raman-spectroscopic characterization of some commercially available carbon-black materials[J].Carbon,1995,33(11):1561-1565.
[28]Pimenta MA,Dresselhaus G,Dresselhaus MS,et al.Studying disorder in graphite-based systems by Raman spectroscopy[J].Physical Chemistry Chemical Physics,2007,9(11):1276-1291.
[29]Knight DS,White WB.Characterization of diamond films by raman-spectroscopy[J].Journal of Materials Research,1989,4(2):385-393.
[30]Ferrari AC,Robertson J.Interpretation of Raman spectra of disordered and amorphous carbon[J].Phys Rev B,2000,61(20):14095-14107.