新型炭材料

XU Zhong-yu, FAN Chang-ling, YIN Du-lin

2004, 19(04): 241-248.

Abstract(2897)

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Abstract:
An artificial graphite with a good structure for lithium-ion storage was selected as the negative electrode material in lithium ion batteries. The galvanostatic performance and the cyclic voltammetric characteristics were investigated in six electrolytes. The compositions and the contents of the solid electrolyte interphase films formed on the surfaces of the graphite sample were analyzed by FTIR. Results show that if the selected electrolyte can react with the surface of the particles of artificial graphite moderately and form a thin and compact solid electrolyte interphase film through which only the lithium ions are permitted to pass, this kind of electrolyte is compatible with the graphitic negative electrode material.

炭化温度对竹炭微观结构及电性能的影响

JIANG Ze-hui, ZHANG Dong-sheng, FEI Ben-hua, YUE Yong-de, CHEN Xiao-hong

2004, 19(04): 249-253.

Abstract(4918)

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Five year old bamboo was carbonized under N2 atmosphere. The effect of carbonization temperature on microstructure, elemental content and resistance were investigated by TGA, SEM, EDXA and XRD. Results show that shrinkage of bamboo during carbonization increases with increasing carbonization temperature, the section shrinkage is 21%, 38% and 40% for 500℃, 750℃ and 1000℃ respectively. The microcrystalline structure of bamboo charcoal tends to a transitional state that leads to graphite. The carbon content and resistance of bamboo charcoal depend on carbonization temperature and radial location. The carbon content of bamboo charcoal carbonized at 500℃ increases from the outer to inner surfaces. An abrupt decrease of resistance is found at 750℃, which shows a 98 to 187 times decrease from outer to inner surface as compared with those values at 500℃. The electrical conductivity of the charcoal is directly related to the carbonization temperature because increasing carbonization temperature increases the crystallite size and decreases ash content, both of which are favorable for increasing the conductivity.

磷氮硼(PNB)系催化剂处理对粘胶纤维热裂解行为的影响

LI Hui, WEN Yue-fang, YANG Yong-gang, LIU Lang

2004, 19(04): 254-260.

Abstract(4066)

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Abstract:
Catalysts play a key role in the manufacture of rayon-based carbon fibers. The pyrolysis behavior of rayon fibers treated with boron (B), phosphorous-nitrogen (PN) and boron-phosphorous-nitrogen (PNB) containing catalysts were investigated by thermogravimetry- mass spectrometry (TG-MS) analysis in an inert atmosphere. It is found that the addition of B, PN and PNB resulted in a lower pyrolysis temperature and an increase of char, water and carbon dioxide at 600℃. PN and PNB restrained the formation of tar, aldehyde derivatives and furan derivatives whereas B did not. The catalysis of B and PN used together is more effective than the single use of B or PN because of their cooperative effect on the pyrolysis of rayon fiber.

添加纳米碳管对高密度聚乙烯力学行为和结晶过程的影响

TONG Xin, HE Xiu-juan, CHENG Hui-ming

2004, 19(04): 261-267.

Abstract(3632)

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Abstract:
Carbon nanotube (CNT)/high-density polyethylene (HDPE) composites with different CNT fractions were prepared by melting the blend, and the mechanical properties and crystallization of the CNT/HDPE composites-obtained were investigated. It was found that the tensile modulus of the CNT/HDPE composites with 2 w/%, 5w/% and 10w/% CNTs are increased by 7.4%, 27.0% and 28.6%, respectively, and the yield strength is increased by 3.3%, 14.4% and 18.5%, respectively, but their strength and elongation at fracture are decreased. The differential scanning calorimetry (DSC) results show that the onset temperature of crystallization (T0) of HDPE is increased and the activation energy of crystallization is decreased due to the presence of CNTs, but its crystallization rate and crystallinity are decreased due to the hindering of the movement of the HDPE molecular chains by CNTs during crystallization.

氨化对湿纺PAN初生丝条结构的影响

REN Fu-zhong, LU Chun-xiang, LIANG Xiao-yi, WU Gang-ping, HE Fu, LING Li-cheng

2004, 19(04): 268-274.

Abstract(4570)

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Abstract:
An aminated PAN resin was spun by wet-spinning technology. The influence of amination degree on the hydrophilicity of the PAN resin was characterized by the contact angle method. The effect of coagulation temperature, dimethylsulfoxide concentration in the coagulation bath and aminating degree on cross-sectional morphologies of the nascent filament and void structure were investigated by optical microscopy, SEM and mercury porosimetry. Results show that the cross-section shape gets more and more circular with increasing of aminating degree and coagulation temperature. The total void volume decreases with the aminating degree. Some large voids with diameter ranging from 6mm to 100mm were transformed to small voids below 140nm when the aminating degree was enhanced. The proportion of large voids in the total void volume was decreased with increasing coagulation temperature and dimethylsulfoxide concentration.

人工神经网络建模在抗烧蚀炭/炭复合材料基体改性研究中的应用

CHEN Qiang, LI He-jun, LI Ai-jun, SUN Guo-ling, LI Ke-zhi

2004, 19(04): 275-280.

Abstract(3398)

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Abstract:
A matrix-modification process has great importance for carbon/carbon (C/C) composites. It is the main method to protect C/C composites from oxidation. As is well known, the matrix modification effects are influenced by many complicated factors, so a mathematical model cannot be exactly formulated. In this paper an artificial neural network (ANN) model is developed to predict the burning rate of matrix-modified C/C composites by the use of the Levenberg-Marquardt algorithm. The relationship between the modifying additives and burning rate is analyzed on the basis of the model. Results show that the relative error between the expected value and the predicted output of the network is less than 0.5%. Employing the ANN model, an optimized combination of these additives is obtained. The burning rate of the additive-optimized C/C composite decreases by 49.3%, which indicates that the ANN model is effective and feasible and could be used to reveal the relationships between the additive contents and the burning rate of C/C composites.

非均相成核中间相炭微球的形成过程及其结构演变

LI Tong-qi, WANG Cheng-yang, ZHENG Jia-ming, WANG Hui

2004, 19(04): 281-288.

Abstract(3092)

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Abstract:
A series of mesocarbon microbeads (MCMB) and small carbonaceous particles (SCP) with size less than 0.5μm were prepared from a coal tar pitch containing quinoline insolubles at 410℃ by varying the holding time. By analyzing softening point and solubility of the as-received mesophase pitches, morphologies of the MCMB and SCP, and cross-section area of the MCMB, it was found that the development of the MCMB formed through heterogeneous nucleation did not follow the coalescence development as the homogeneous nucleation of MCMB but kept to the process of Building from Spherical Basic Units (BSBU), in which spherical SCP were the basic units to build MCMB spheres. During this process, the viscosity of the system was the important factor that had great influence in the production of MCMB and SCP. The internal microtextures of MCMB were none of the three model structures of global type, onion type and concentric circles type, but a complex structure with the carbon layers converging at one or two points. With increased the holding time, the structures of MCMB did not inherit the previously formed structures, but the carbon layers changed and rearranged into new types. The main tendency of the carbon layer rearrangement in MCMB was not to make the carbon layers parallel but to make them become larger.

压力梯度CVI工艺制备2D炭/炭复合材料的弯曲断裂行为(英)

XUE Hui, LI He-jun, HOU Xiang-hui, LI Ke-zhi, HAN Hong-mei

2004, 19(04): 289-292.

Abstract(3367)

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Abstract:
The flexural behavior of 2D carbon-carbon (C/C) composites fabricated by CVI was investigated using a three-point bend test, and the fracture surface and interface of the composites were observed by SEM. By analyzing the effects of the fiber-matrix interface and the sample density on the mechanical behavior, it is revealed that the fracture modes of 2D C/C composites change from shearing and delamination failure to tensile breakage with increasing densification degree. The results also show that the density has a great impact on the strength and modulus rather than the flexural deflection. In fact, the flexural deflection of 2D C/C composites depends on the performance of the pyrocarbon and the interfacial bonding between fibers and matrix.

煤-树脂混合物残炭的形貌分析(英)

Imtiaz Ahmad, Mohammad Ishaq, Mohammad Arsala Khan, Mohammad Shakir Ullah, Ali Bahader

2004, 19(04): 293-297.

Abstract(3273)

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Abstract:
Carbonaceous residues obtained by carbonizing virgin and various coal-polymer mixtures in a micro autoclave at temperatures of 350℃ and 400℃ were investigated by scanning electron microscopy. Results show that hydrogen-rich macerals are disintegrated while other macerals like fusain, and exinite are resistant to disintegration. Addition of polymers like low & high density polypropylene and polystyrene leads to an increased disintegration of the macerals and alters the morphologies of the residues.

不同原料气催化热解法制备碳纳米管的研究

LI Ying, LI Xuanke, LIU Lang

2004, 19(04): 298-302.

Abstract(4766)

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Abstract:
Carbon nanotubes were prepared by catalytic decomposition of CH4 or C3H6, and the effect of source gases on the yield and morphologies of the carbon nanotubes was investigated. When CH4 is used, besides a higher conversion, the resultant carbon nanotubes have a more regular and more homogenous morphology as evidenced by TEM. The XRD patterns of the products from both source gases are similar to that of graphite, but the degree of long-range order of these nanostructures is relatively low. Compared with the carbon nanotubes produced from C3H6, the carbon nanotubes produced from CH4 have a higher degree of long-range order, which suggests that CH4 is a more suitable source gas to produce carbon nanotubes. The Raman spectrum indicates that there are more defects in the structure of carbon nanotubes produced from C3H6 than from CH4.

质子交换膜燃料电池复合材料双极板的研究

ZOU Yan-wen, ZHANG Jie, HE Jun, ZHENG Yong-ping, TANG Ya-ping, SUN Bin, QIU Xue-liang

2004, 19(04): 303-308.

Abstract(3857)

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Abstract:
The influences of the different conductive fillers (graphite), resins, pressures and temperature on the properties of resin/graphite composite PEMFC bipolar plates were investigated. Results show that the components of conductive filler, and the sort and content of resin have a larger effect on the composite properties than do the pressure and temperature. Bipolar plates using a mixture of natural graphite and electrographite as conductive filler are better than that using a single component. The resin content, molding pressures and temperature should be 16-18 w/%, 10-20MPa and 150-200℃, respectively. The composite bipolar plates obtained have a conductivity over 300S/cm, a flexural strength over 30MPa and a permeability of 10-7 cm2/s.

天然准纳米针状石墨的发现及其结构表征

FENG You-li, ZHENG Zhe, GUO Yan-jun, YU Li-jing

2004, 19(04): 309-311.

Abstract(2463)

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Abstract:
One sort of long needle mineral with 12500nm length and 150nm width was discovered in ball-like graphite from Sujiquan granite, Xinjiang, China. Analysis by X-ray energy dispersive spectrometry (XEDS) attached to a high resolution transmission electron microscope (HRTEM) shows that it is composed of carbon. Selected area electron diffraction (SAED) illustrates that its crystal structure is 2H type graphite. Thus, this mineral can be confirmed as quasi-nanometer needle graphite because its width of 150nm is only slightly larger than the 100nm nanometer scale limit. Its rim is straight as are the fringes of the crystal planes. This quasi nanometer needle graphite should have outstanding mechanical characteristics.

碳纳米管溶解性及其化学修饰

JIN Wei-jun, SUN Xu-feng, WANG Yu

2004, 19(04): 312-318.

Abstract(4804)

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Abstract:
This review introduces in detail the routes to improving the solubility of CNTs in water or organic solvents by noncovalent interaction, i.e., straight dispersion in a single solvent, charge transfer between electron donor and acceptor, the wrapping effect of soluble polymers or cylindrical micelles, etc., and by the covalent chemical modification of the carbon nanotubes, i.e., end-opening, chemical derivitization and side-wall chemical modification etc. Finally, it points out that the focus of carbon nanotube science in future years should be on improving the properties of carbon nanotubes by noncovalent or covalent chemical modification, on extending the application fields of carbon nanotubes by coupling chemical, biological and physical function to carbon nanotubes, and also on a deeper understanding of the reaction theory of carbon nanotubes in solution.

新金刚石

WEN Bin

2004, 19(04): 319-319.

Abstract(3020)

PDF(2905)

Abstract:

2004 Vol. 19, No. 04

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