基于SAXS方法的核石墨微孔结构的温度影响
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摘要
X射线小角散射(Small Angle X-ray Scattering,SAXS)是研究纳米尺度微观结构的重要手段。本文利用同步辐射SAXS技术测量了25oC、100oC、200oC、300oC和400oC时,IG-110和NBG-18核石墨在纳米尺度范围内孔隙的数量分布及其分形特征的变化。实验结果表明,IG-110和NBG-18核石墨的微观结构中存在微小尺寸上的不均匀区域,且核石墨孔隙的固气结构具有明锐的界面。但随着温度的升高,固气界面的变化并没有呈现出明显的规律性。此外,在纳米尺度上,IG-110和NBG-18核石墨的孔隙数量随温度呈现增加的趋势,且IG-110核石墨孔隙数量的增加幅度大于NBG-18核石墨,其平均孔隙尺寸的减小幅度大于NBG-18核石墨。在核石墨的微孔结构内,其固气界面的分形维数随温度升高逐渐减小,且NBG-18核石墨分形维数的变化幅度小于IG-110核石墨。这表明核石墨的分形结构随温度的升高逐渐光滑。
Background: The distribution of nanoscale pore is of great significance to irradiation damage behavior of nuclear graphite under intense radiation. Small angle X-ray scattering(SAXS) is an important method used to study the number distribution and its fractal characteristics of pore in nanoscale. Purpose: This study aims at the changes in number distribution and its fractal characteristics of nanoscale pore in nuclear graphite. Methods: Two typical nuclear graphite, i.e., IG-110 and NBG-18 were sampled and tested at synchrotron radiation SAXS beamline station at temperatures of 25 oC, 100 oC, 200 oC, 300 oC and 400 oC, respectively. Results: The results showed that there was a non-uniform area in the microstructure of nuclear graphite, and the solid-gas structure of the nuclear graphite pore had a sharp interface, but the change of solid-gas interface does not show obvious regularity with the increase of temperature. In addition, the number of nanoscale pore in IG-110 nuclear graphite increases with the temperature, and is more obvious than that of NBG-18. The fractal dimension of the solid-gas interface decreases with the temperature increasing, indicating that the fractal structure of the graphite become smoother with the increasing of temperature. And the change of IG-110 is more obvious than that of NBG-18. Conclusion: The temperature has a significant impact on the pore number distribution and its fractal characteristics.
Background: The distribution of nanoscale pore is of great significance to irradiation damage behavior of nuclear graphite under intense radiation. Small angle X-ray scattering(SAXS) is an important method used to study the number distribution and its fractal characteristics of pore in nanoscale. Purpose: This study aims at the changes in number distribution and its fractal characteristics of nanoscale pore in nuclear graphite. Methods: Two typical nuclear graphite, i.e., IG-110 and NBG-18 were sampled and tested at synchrotron radiation SAXS beamline station at temperatures of 25 oC, 100 oC, 200 oC, 300 oC and 400 oC, respectively. Results: The results showed that there was a non-uniform area in the microstructure of nuclear graphite, and the solid-gas structure of the nuclear graphite pore had a sharp interface, but the change of solid-gas interface does not show obvious regularity with the increase of temperature. In addition, the number of nanoscale pore in IG-110 nuclear graphite increases with the temperature, and is more obvious than that of NBG-18. The fractal dimension of the solid-gas interface decreases with the temperature increasing, indicating that the fractal structure of the graphite become smoother with the increasing of temperature. And the change of IG-110 is more obvious than that of NBG-18. Conclusion: The temperature has a significant impact on the pore number distribution and its fractal characteristics.
引文
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20王海伟,蔡翔舟,梅龙伟,等.熔盐堆堆芯分区结构对钍燃料增殖性能的影响[J].核技术,2013,36(9):090601.DOI:10.11889/j.0253-3219.2013.hjs.36.090601.WANG Haiwei,CAI Xiangzhou,MEI Longwei,et al.Impact on breeding rate of different molten salt reactor core structures[J].Nuclear Techniques,2013,36(9):090601.DOI:10.11889/j.0253-3219.2013.hjs.36.090601.
21邱咏梅,但贵萍,文炜,等.反应堆堆本体材料中14C制样系统的研制[J].核技术,2015,38(5):050302.DOI:10.11889/j.0253-3219.2015.hjs.38.050302.QIU Yongmei,DAN Guiping,WEN Wei,et al.Sample preparation system of 14C in the main materials of nuclear reactor[J].Nuclear Techniques,2015,38(5):050302.DOI:10.11889/j.0253-3219.2015.hjs.38.050302.
22 Yuan X,Duan Y,He L,et al.Characterization of white poplar and eucalyptus after ionic liquid pretreatment as a function of biomass loading using X-ray diffraction and small angle neutron scattering[J].Bioresource Technology,2017,232:113-118.DOI:10.1016/j.biortech.2017.02.014.
23 Wang W,Li L,Henzler K,et al.Protein immobilization onto cationic spherical polyelectrolyte brushes studied by small angle X-ray scattering[J].Biomacromolecules,2017,18(5):1574-1581.DOI:10.1021/acs.biomac.7b00164.
24 Mileeva Z,Ross D K,King S M.A study of the porosity of nuclear graphite using small-angle neutron scattering[J].Carbon,2013,64(9):20-26.DOI:10.1016/j.carbon.2013.06.030.
25 Coetzee G H,Sakurovs R,Neomagus H W J P,et al.Pore development during gasification of South African inertinite-rich chars evaluated using small angle X-ray scattering[J].Carbon,2015,95:250-260.DOI:10.1016/j.carbon.2015.08.030.
26 Radlinski A P,Mastalerz M,Hinde A L,et al.Application of SAXS and SANS in evaluation of porosity,pore size distribution and surface area of coal[J].International Journal of Coal Geology,2004,59(3-4):245-271.DOI:10.1016/j.coal.2004.03.002.
27朱育平.小角X射线散射-理论、测试、计算及应用[M].北京:化学工业出版社,2008:151-156.ZHU Yuping.Small angle X-ray scattering-theory,test,calculate and apply[M].Beijing:Chemical Industry Press,2008:151-156.
28 Tian F,Li X H,Wang Y Z,et al.Small angle X-ray scattering beamline at SSRF[J].Nuclear Science and Techniques,2015,26(3):030101.DOI:10.13538/j.1001-8042/nst.26.030101.
2 Mcenaney B.Relating measurements of mechanical properties of nuclear graphites to reactor conditions:a review of the effects of temperature and pressure[J].Special Publication Royal Society of Chemistry,2007,309(8):51-58.
3 Kelly B T.The theory of irradiation damage in graphite[J].Carbon,1977,15(2):117-127.DOI:10.1016/0008-6223(77)90027-6.
4 Kelly B T.Graphite-the most fascinating nuclear material[J].Carbon,1982,20(1):2-11.DOI:10.1016/0008-6223(82)90066-5.
5 Woolley R L.On the theory of irradiation damage in graphite at power reactor temperatures[J].British Journal of Applied Physics,1963,14(11):778-783.DOI:10.1088/0508-3443/14/11/311.
6 Marsden B J.Managing nuclear graphite ageing[J].Nuclear Energy,2002,41(2):145-154.DOI:10.1680/nuen.41.2.145.39019.
7 Matsuo H.The effect of porosity on the thermal conductivity of nuclear graphite[J].Journal of Nuclear Materials,1980,89(1):9-12.DOI:10.1016/0022-3115(80)90003-3.
8 Sutton A L,Howard V C.The role of porosity in the accommodation of thermal expansion in graphite[J].Carbon,1962,7(1):367-368.DOI:10.1016/0008-6223(64)90338-0.
9 Cataldo F,Ursini O,Nasillo G,et al.Thermal properties,Raman spectroscopy and Tem images of neutron-bombarded graphite[J].Fullerenes,Nanotubes and Carbon Nanostructures,2013,21(7):634-643.DOI:10.1080/1536383x.2012.654533.
10 Karthik C,Kane J,Butt D P,et al.Microstructural characterization of next generation nuclear graphites[J].Microscopy and Microanalysis,2012,18(2):272-278.DOI:10.1017/s1431927611012360.
11 Yoon J H,Byun T S,Strizak J P,et al.Characterization of tensile strength and fracture toughness of nuclear graphite NBG-18 using subsize specimens[J].Journal of Nuclear Materials,2011,412(3):315-320.DOI:10.1016/j.jnucmat.2011.03.019.
12 Tsang D K L,Marsden B J.Effects of dimensional change strain in nuclear graphite component stress analysis[J].Nuclear Engineering&Design,2007,237(9):897-904.DOI:10.1016/j.nucengdes.2006.01.015.
13 Matsuo H.The effect of residual strain on the thermal-conductivity of nuclear graphite[J].Journal of Nuclear Materials,1980,92(1):39-42.DOI:10.1016/0022-3115(80)90139-7.
14 Kurosawa T,Imai H,Nomura S,et al.Changes in thermal-expansion coefficient of nuclear graphite caused by pre-stressing[J].Carbon,1977,15(3):189-191.DOI:10.1016/0008-6223(77)90057-4.
15 Kim E S,No H C.Experimental study on the oxidation of nuclear graphite and development of an oxidation model[J].Journal of Nuclear Materials,2006,349(1-2):182-194.DOI:10.1016/j.jnucmat.2005.10.015.
16 Penner S S,Richards M B.Oxidation of nuclear-reactorgrade graphite[J].Energy,1988,13(6):461-468.DOI:10.1016/0360-5442(88)90001-1.
17 Lewis J B,Murdoch R,Hawtin P.Thermal oxidation of nuclear graphite[J].British Nuclear Energy Society,1964,3(2):95-103.
18 Li H Y,Marsden B J,Fok S L.Relationship between nuclear graphite moderator brick bore profile measurement and irradiation-induced dimensional change[J].Nuclear Engineering&Design,2004,232(3):237-247.DOI:10.1016/j.nucengdes.2004.06.006.
19 Wen K,Marrow J,Marsden B.Microcracks in nuclear graphite and highly oriented pyrolytic graphite(HOPG)[J].Journal of Nuclear Materials,2008,381(1-2):199-203.DOI:10.1016/j.jnucmat.2008.07.012.
20王海伟,蔡翔舟,梅龙伟,等.熔盐堆堆芯分区结构对钍燃料增殖性能的影响[J].核技术,2013,36(9):090601.DOI:10.11889/j.0253-3219.2013.hjs.36.090601.WANG Haiwei,CAI Xiangzhou,MEI Longwei,et al.Impact on breeding rate of different molten salt reactor core structures[J].Nuclear Techniques,2013,36(9):090601.DOI:10.11889/j.0253-3219.2013.hjs.36.090601.
21邱咏梅,但贵萍,文炜,等.反应堆堆本体材料中14C制样系统的研制[J].核技术,2015,38(5):050302.DOI:10.11889/j.0253-3219.2015.hjs.38.050302.QIU Yongmei,DAN Guiping,WEN Wei,et al.Sample preparation system of 14C in the main materials of nuclear reactor[J].Nuclear Techniques,2015,38(5):050302.DOI:10.11889/j.0253-3219.2015.hjs.38.050302.
22 Yuan X,Duan Y,He L,et al.Characterization of white poplar and eucalyptus after ionic liquid pretreatment as a function of biomass loading using X-ray diffraction and small angle neutron scattering[J].Bioresource Technology,2017,232:113-118.DOI:10.1016/j.biortech.2017.02.014.
23 Wang W,Li L,Henzler K,et al.Protein immobilization onto cationic spherical polyelectrolyte brushes studied by small angle X-ray scattering[J].Biomacromolecules,2017,18(5):1574-1581.DOI:10.1021/acs.biomac.7b00164.
24 Mileeva Z,Ross D K,King S M.A study of the porosity of nuclear graphite using small-angle neutron scattering[J].Carbon,2013,64(9):20-26.DOI:10.1016/j.carbon.2013.06.030.
25 Coetzee G H,Sakurovs R,Neomagus H W J P,et al.Pore development during gasification of South African inertinite-rich chars evaluated using small angle X-ray scattering[J].Carbon,2015,95:250-260.DOI:10.1016/j.carbon.2015.08.030.
26 Radlinski A P,Mastalerz M,Hinde A L,et al.Application of SAXS and SANS in evaluation of porosity,pore size distribution and surface area of coal[J].International Journal of Coal Geology,2004,59(3-4):245-271.DOI:10.1016/j.coal.2004.03.002.
27朱育平.小角X射线散射-理论、测试、计算及应用[M].北京:化学工业出版社,2008:151-156.ZHU Yuping.Small angle X-ray scattering-theory,test,calculate and apply[M].Beijing:Chemical Industry Press,2008:151-156.
28 Tian F,Li X H,Wang Y Z,et al.Small angle X-ray scattering beamline at SSRF[J].Nuclear Science and Techniques,2015,26(3):030101.DOI:10.13538/j.1001-8042/nst.26.030101.