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nano-to micro-pore characterization by synchrotron radiation SAXS and nano-ct for bituminous coals

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Frontiers of Earth Science 2021年第2期15卷 189-201页

作者： Yixin ZHAO Chujian HAN Yingfeng SUN Nima Noraei DANESH Tong LIU Yirui GAO Beijing Key Laboratory for Precise Mining of Intergrown Energy and Resources China University of Mining and Technology(Beijing)Beijing 100083China School of Energy and Mining Engineering China University of Mining and Technology(Beijing)Beijing 100083China School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China Key Laboratory of Deep Earth Science and Engineering(Ministry of Education) Sichuan UniversityChengdu 610065China

Considering the complementarity of synchrotron radiation SAXS and nano-ct in the pore structure detection range,synchrotron radiation SAXS and nano-ct methods were combined to characterize the nano-to micropore structure of two bituminous coal samples.In mesopores,the pore size distribution curves exhibit unimodal distribution and the average pore diameters are similar due to the affinity of metamorphic grades of the two samples.In macropores,the sample with higher mineral matter content,especially clay mineral content,has a much higher number of pores.The fractal dimensions representing the pore surface irregularity and the pore structure heterogeneity were also characterized by synchrotron radiation SAXS and nano-ct.The fractal dimensions estimated by both methods for different pore sizes show consistency and the sample with smaller average pore diameters has a more complex pore structure within the full tested range.

关键词： synchrotron radiation SAXS nano-ct pore size distribution fractal coal

The 3D nanoimaging beamline at SSRF

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Nuclear Science and Techniques 2023年第12期34卷 242-250页

作者： Ling Zhang Fen Tao Jun Wang Ruo‑Yang Gao Bo Su Guo‑Hao Du Ai‑Guo Li Ti‑Qiao Xiao Biao Deng Shanghai Synchrotron Radiation Facility Shanghai Advanced Research InstituteChinese Academy of SciencesShanghai 201204China

Full-field transmission X-ray microscopy(TXM)is a powerful non-destructive three-dimensional(3D)imaging method with a nanoscale spatial resolution that has been used in most synchrotron facilities worldwide.An in-house-designed TXM system was constructed at the BL18B 3D nanoimaging beamline at the Shanghai Synchrotron Radiation Facility.The beamline operates from 5 to 14 keV and enables 20 nm spatial resolution imaging.The characterization details of the beamline are described in this paper.The performances in terms of spatial resolution,nano-ct,and nano-spectral imaging of the TXM beamline are also presented in this article.

关键词： Transmission X-ray microscopy(TXM) nano-ct Synchrotron radiation

基于nano-ct重构催化层微结构中传输过程与相变特征研究

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基于Nano-CT重构催化层微结构中传输过程与相变特征研究

作者：杨小祥武汉理工大学

学位级别：硕士

质子交换膜燃料电池(Proton Exchange Membrane Fuel Cell:PEMFC)具有效率高、响应速度快等优点,被认为是最有前途的能量转换装置之一。在PEMFC的组成中,夹在微孔层和膜之间的催化剂层(Catalyst Layer:CL)是最复杂和最重要的,因为它是... 详细信息

质子交换膜燃料电池(Proton Exchange Membrane Fuel Cell:PEMFC)具有效率高、响应速度快等优点,被认为是最有前途的能量转换装置之一。在PEMFC的组成中,夹在微孔层和膜之间的催化剂层(Catalyst Layer:CL)是最复杂和最重要的,因为它是发生能量转换的地方。PEMFC催化层微观结构对燃料电池性能的影响并不像其它组成结构那样简单,因为催化层中的各种组分和输运过程相互影响。因此,需要全面了解催化层微观结构及其与相应传输机制的相互作用,以改善催化层在各种条件下的性能。本文基于nano-ct技术重构PEMFC催化层三维微观结构,考虑微纳尺度下Knudsen效应,利用细观CFD方法,对其中热、质传输及电化学过程进行模拟。主要获得以下结论:(1)催化层中气体的有效扩散系数随着孔隙率增大而增大;考虑Knudsen扩散时的有效扩散系数均小于不考虑Knudsen效应时的值;Bruggmen高估了气体有效扩散系数。催化层中有效电子电导率/有效质子电导率随碳/离聚物体积分数增大而增大。(2)电化学反应从CL/PEM界面向CL/GDL界面逐渐进行,电流密度逐渐降低;计算条件下,质子传导是影响反应强度的主要因素;3s时体系基本稳定。(3)O浓度从CL/GDL界面向CL/PEM界面逐渐降低。温度分布趋势与电流密度一致,体系稳定时CL/PEM与CL/GDL界面温差为0.2 K;从开始到稳定,催化层整体温度增加了0.6 K左右。(4)液态水饱和度从CL/PEM界面向CL/GDL界面逐渐降低;在任意等值面上,膜态水分布呈丘陵状,高低起伏,造成这一现象的原因与催化层内部复杂的孔结构、各处电化学反应强度及离聚物润湿度有关。(5)催化层中存在一定量的死孔(Dead pore),O无法进入,因此也不会发生电化学反应;多处半岛式结构中氧气与质子的传输不匹配,影响反应的效率。

关键词：质子交换膜燃料电池催化层微结构 nano-ct 重构传输过程

Synchrotron radiation facility-based quantitative evaluation of pore structure heterogeneity and anisotropy in coal

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Petroleum Exploration and Development 2019年第6期46卷 1195-1205页

作者： SUN Yingfeng ZHAO Yixin WANG Xin PENG Lei SUN Qiang School of Energy and Mining Engineering China University of Mining and Technology(Beijing)Beijing 100083China School of Emergency Management and Safety Engineering China University of Mining and Technology(Beijing)Beijing 100083China Beijing Key Laboratory for Precise Mining of Intergrown Energy and Resources China University of Mining and Technology(Beijing)Beijing 100083China School of Mechanics and Civil Engineering China University of Mining and Technology(Beijing)Beijing 100083China Research Institute of Petroleum Exploration&Development PetroChinaBeijing 100083China

In order to quantify coal pore structure heterogeneity and anisotropy,synchrotron radiation SAXS(Small Angle X-ray Scattering)was applied to obtain the SAXS images of two different rank coal samples.The surface fractal dimension(D1)and pore fractal dimension(D2)were obtained by processing the image data.The pore structure heterogeneity of two coal samples was quantified by pore fractal dimension(D2).Pore fractal dimension of Xinzhouyao coal is 2.74 and pore fractal dimension of Tangshan coal is 1.69.As a result,the pore structure heterogeneity of Xinzhouyao coal is stronger than that of Tangshan coal.3D pore structure imaging was achieved by synchrotron radiation nano-ct.The selected Region of Interest(ROI)of coal sample was divided into a certain number of subvolumes.Pore structure heterogeneity was quantified by calculating the limit of the relative standard deviation of each subvolume’s porosity.The heterogeneity value of Xinzhouyao coal pore structure is 3.21 and the heterogeneity value of Tangshan coal pore structure is 2.71.As a result,the pore structure heterogeneity of Xinzhouyao coal is also stronger than that of Tangshan coal,namely,pore structure heterogeneity from synchrotron radiation SAXS and synchrotron radiation nano-ct is consistent.Considering the corresponding relationship between the pore structure anisotropy and the permeability anisotropy,the quantification of pore structure anisotropy was realized by computing the permeability tensor of pore structure using the Lattice Boltzmann method(LBM),and the pore structure anisotropy was characterized by the eigenvalues and eigenvectors of the permeability tensor.The pore structure anisotropy obtained by the method proposed in this paper was validated by the pore structure geometrical morphology.

关键词： synchrotron radiation SAXS synchrotron radiation nano-ct coal pore structure heterogeneity anisotropy

Revisiting Silica Networks by Small-angle Neutron Scattering and Synchrotron Radiation X-ray Imaging Techniques

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Chinese Journal of Polymer Science 2020年第9期38卷 1006-1014,I0008页

作者： Xin-Wei Kang Dong Liu Ping Zhang Ming Kang Feng Chen Qing-Xi Yuan Xiu-Li Zhao Ying-Ze Song Li-Xian Song State Key Laboratory of Environment-Friendly Energy Materials Southwest University of Science and TechnologyMianyang 621010China Key Laboratory of Neutron Physics Institute of Nuclear Physics and ChemistryChina Academy of Engineering PhysicsMianyang 621999China Beijing Synchrotron Radiation Facility Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China Institute of Chemical Materials China Academy of Engineering PhysicsMianyang 621900China

The silicone rubber composites present remarkable mechanical properties due to the double network structure constructed with molecular network of matrix and filler network of silica.Nevertheless,the filler network structure and corresponding reinforcement mechanism are still under debate and need to be further probed with the aid of applicative advanced analysis techniques.Herein,small-angle neutron scattering(SANS)and synchrotron radiation X-ray nano-computed tomography(nano-ct)techniques are employed to explore the evolution of filler networks of fumed,precipitated and sol-gel silica,respectively.Our studying results reveal the formation of filler network constructed by the interconnecting of branched silica aggregates.And the silica with highly associated structure,pertaining to amorphous morphology,small size,and large surface area,presents short distance and effective molecular chain bridge between aggregates,thus forming strong and steady filler networks.This work would provide deep-seated revisiting of filler networks and corresponding reinforcement mechanism and offer guidance for optimizing the mechanical properties of silicone rubber.

关键词： Silica networks Reinforcement mechanism SANS nano-ct

Mechanism of CO_(2) enhanced oil recovery in shale reservoirs

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Petroleum Science 2021年第6期18卷 1788-1796页

作者： Hai-Bo Li Zheng-Ming Yang Rui-Shan Li Ti-Yao Zhou He-Kun Guo Xue-Wei Liu Yi-Xin Dai Zhen-Guo Hu Huan Meng PetroChina Research Institute of Petroleum Exploration and Development Beijing100083PR China Institute of Flow and Fluid Mechanics Chinese Academy of SciencesLangfang065007HebeiPR China Sinopec Jianghan Oilfield Company Research Institute of Exploration and Development Wuhan430223HubeiPR China University of Chinese Academy of Sciences Beijing100049PR China

Combined with NMR,core experiment,slim-tube tests,nano-ct and oil composition analysis,the mechanism of CO(2) enhanced oil recovery had been studied.CO_(2) flooding under supercritical state could achieve higher oil recovery.In the process of crude oil displaced by supercritical CO2,the average oil recovery was 46.98% at low displacement pressures and 73.35% at high displacement pressures.The permeability of cores after CO2 flooding was only 28%-64% of those before flooding.As to the expelled oil,the contents of asphaltenes and non-hydrocarbons decreased,and saturated hydrocarbons of above C25 were absent in some samples,indicating that they had been retained in cores as demonstrated by ct and NMR experiments.In slim-tube tests,the heavy components of oil were expelled when the pressure increased to 30 MPa.There was a reasonable bottom hole pressure(BHP) below which the heavy components driven out from the far-well zone would deposit in the near-well zone,and when the pressure was too high,the nonhydrocarbon detention may cause block.The smaller throat and worse physical properties the porous media had,the higher displacement pressure would be required to achieve a good oil displacement efficiency.The increase in displacement pressure or time of interaction between oil and CO2 could effectively enhance oil recovery.

关键词： Shale oil CO_(2) Supercritical pressure NMR Core physical simulation Slim-tube test Component analysis nano-ct

Study of the numerical simulation of tight sandstone gas molecular diffusion based on digital core technology

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Petroleum Science 2018年第1期15卷 68-76页

作者： Hong-Lin Zhu Shou-Feng Wang Guo-Jun Yin Qiao Chen Feng-Lin Xu Wei Peng Yan-Hu Tan Kuo Zhang Chongqing Institute of Green and Intelligent Technology Chinese Academy of Sciences State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum University Oil and Gas Engineering Research Institute Jilin Oilfield Company PetroChina Shu’nan Gas Mine Southwest Oil and Gas Field Branch Company PetroChina Co. Ltd

Diffusion is an important mass transfer mode of tight sandstone gas. Since nano-pores are extensively developed in the interior of tight sandstone, a considerable body of research indicates that the type of diffusion is mainly molecular diffusion based on Fick＇s law. However, accurate modeling and understanding the physics of gas transport phenomena in nanoporous media is still a challenge for researchers and traditional investigation（analytical and experimental methods） have many limitations in studying the generic behavior. In this paper, we used nano-ct to observe the pore structures of samples of the tight sandstone of western of Sichuan. Combined with advanced image processing technology, threedimensional distributions of the nanometer-sized pores were reconstructed and a tight sandstone digital core model was built, as well the pore structure parameters were analyzed quantitatively. Based on the digital core model, the diffusion process of methane molecules from a higher concentration area to a lower concentration area was simulated by a finite volume method. Finally, the reservoir＇s concentration evolution was visualized and the intrinsic molecular diffusivity tensor which reflects the diffusion capabilities of this rock was calculated. Through comparisons, we found that our calculated result was in good agreement with other empirical results. This study provides a new research method for tight sandstone digital rock physics. It is a foundation for future tight sandstone gas percolation theory and numerical simulation research.

关键词： Tight sandstone gas nano-ct Digital core Molecular diffusion Numerical simulation

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ZrB2基超高温陶瓷无损检测研究

ZrB2基超高温陶瓷无损检测研究

作者：丁尧哈尔滨工业大学

学位级别：硕士

本文以Zr B2基超高温陶瓷为研究对象,针对其本征脆性及极端条件下材料内部缺陷对性能影响大等问题,利用超声波无损检测及nano-ct的方法实现了超高温陶瓷内部缺陷的精确表征和定量化。首先,研究了超声波不同参数对检测效果的影响,得出换... 详细信息

本文以Zr B2基超高温陶瓷为研究对象,针对其本征脆性及极端条件下材料内部缺陷对性能影响大等问题,利用超声波无损检测及nano-ct的方法实现了超高温陶瓷内部缺陷的精确表征和定量化。首先,研究了超声波不同参数对检测效果的影响,得出换能器的频率越高检测分辨越高,因此采用230MHz高频换能器对不同组分的Zr B2基超高温陶瓷进行检测,并结合微观形貌分析了超声检测的优缺点。同时,对抛光后材料表面粗糙度进行检测,发现鳞片石墨的加入降低了材料的硬度,但材料更易抛光且表面粗糙度最低。然后,采用激光加工的方法在致密的Zr O2和非致密的Zr B2陶瓷表面制备了微米级别的缺陷,基于Zr O2缺陷深度与强度的拟合函数,得到了影响Zr B2陶瓷强度的临界缺陷尺寸。其次,采用nano-ct方法研究坯体不同位置致密度分布及内部缺陷的直径分布、体积分布、取向性和孔洞的形貌信息。通过检测确定了超高温陶瓷内部缺陷为烧结过程中未排尽气体造成的孔洞。基于此,研究了致密度约为93%的Zr B2陶瓷,发现其坯体不同部位致密度差别很大,并通过VG Studio MAX软件对设定方向各区域的平均致密度进行研究,证明了坯体中间部位孔隙率比坯体边上部位高。最后,研究了Si C颗粒及鳞片石墨对超高温陶瓷内部孔洞的影响。认为孔洞数量随直径、体积的增大对数减小。选取边长为300μm立方体区域,发现内部直径小于5μm的孔洞数量占绝大多数。采用孔洞的X、Y轴与Z轴的孔洞边界框尺寸的比值研究孔洞沿热压方向的取向性,得出因坯体中间受压偏移量小导致孔洞的取向性更明显。通过相同的方法分析Zr B2-Si C陶瓷内部孔洞的特征信息,Si C颗粒的加入促进了烧结、抑制了晶粒长大、提高了材料的致密度和强度,且降低孔洞的直径和体积,提升了孔洞的取向性,是由于Si C的平均粒径为500nm,在烧结后期晶格扩散时,填充孔洞且致使孔洞单位表面积受压更大,更易取向。鳞片石墨具有较大的长宽比,在裂纹扩展时增大了偏转路径、消耗了更多能量,提高了材料的断裂韧性。而因其热膨胀系数不同于基体,增大了孔洞的直径和体积,同时,鳞片石墨的高取向性使孔洞的取向性更加明显。

关键词： ZrB2 超高温陶瓷超声波无损检测 nano-ct 孔洞致密化

SiO2/硅橡胶复合体系填料网络的形成与结构表征

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西南科技大学学报 2020年第2期35卷 55-62页

作者：康新尉陈乐陈凤宋丽贤西南科技大学环境友好能源材料国家重点实验室四川绵阳621010 西南科技大学材料科学与工程学院四川绵阳621010

加入纳米二氧化硅填料能显著改善硅橡胶的力学性能。利用小角中子散射(SANS)和同步辐射X射线三维纳米计算机断层扫描(nano-ct)技术协同表征了SiO2/硅橡胶复合体系中填料的聚集形态、填料网络的形成及其结构随填料含量的变化关系。结果表... 详细信息

加入纳米二氧化硅填料能显著改善硅橡胶的力学性能。利用小角中子散射(SANS)和同步辐射X射线三维纳米计算机断层扫描(nano-ct)技术协同表征了SiO2/硅橡胶复合体系中填料的聚集形态、填料网络的形成及其结构随填料含量的变化关系。结果表明:随填料含量的增加,SiO2聚集体的平均粒径和距离均呈现出减小的趋势,填料网络密度和连通率逐渐增加;当填料含量≥40份/100份时,形成了相互连通的填料网络结构。填料网络的形成使硅橡胶复合材料力学性能得到显著提升。

关键词：二氧化硅硅橡胶填料网络小角中子散射 nano-ct