2006 Vol. 21, No. 03

中间相沥青基炭泡沫体的制备、结构及性能
SHEN Zeng-min, GE Min, CHI Wei-dong, LIU Hui
2006, 21(03): 193-201.
Abstract(2759) PDF(2482)
Abstract:
Nascent foams with uniform pore size were produced from naphthalene mesophase pitch in a high pressure chamber, they were carbonized and graphitized by heat treating to 7001000℃ and 23002800℃ to form carbon and graphite foams. The influence of the basic properties of the pitch, foaming and heat treatment parameters on the microstructures and mechanical properties of the foams were investigated. It was found that an uniform temperature environment is the key to the preparation of carbon foams with uniform pore size and that the foaming pressure is the main factor for the control of pore size. The microstructure, crystal structure and microwave absorbing properties of carbon foams exhibited an anisotropic characteristic in the xz and xyplane directions (parallel and perpendicular to the gravitational directions, respectively).
淀粉基碳包覆铁纳米胶囊的合成及其磁学性能
QIU Jie-shan, SUN Yu-feng, ZHOU Ying, SUN Tian-jun, LI Qi-xiu
2006, 21(03): 202-205.
Abstract(3109) PDF(3183)
Abstract:
Carbon encapsulated iron (Fe@C) nanocapsules were successfully prepared by pyrolyzing iron/starch composites under mild conditions, in which starch functioned as carbon precursor and stabilizer for iron nanoparticles. The asobtained Fe@C nanocapsules were examined by TEM, XRD and a vibrating sample magnetometer. Results show that the Fe@C nanocapsules with diameters in a narrow range of 3040nm feature wellconstructed core/shell structures, consisting of a bccFe core and a graphitic shell. The Fe@C nanocapsules have a low ratio of remanence to saturation magnetization (Mr/Ms = 0.11), implying that they are superparamagnetic at room temperature.
利用铈盐改性修饰活性炭纤维结构
CHEN Shui-xia, CHEN Jian-liang, WU Qing-yu
2006, 21(03): 206-212.
Abstract(2677) PDF(2094)
Abstract:
The surface chemical structure of activated carbon fibers (ACF) was modified by cerous nitrate. The pore structure and surface chemical structure were characterized by nitrogen adsorption, Xray photoelectron spectroscopy (XPS) and thermal gravimetric analysisFourier transformation infrared integrated technology. Results show that Ce(IV)treatment can result in about a 1020% decrease of specific surface area of the modified ACF, however this treatment cannot obviously change the micropore size distribution. Surface chemical structure analysis based on XPS indicates that Ce(IV)treatment can evidently increase the oxygen content of ACF from 11 to 25 atom% depending on the concentration of cerous nitrate. In situ IR analysis of the decomposition gases from ACF during heating to high temperature shows that the chemical treatment of ACF with a higher concentration of cerous nitrate can form many oxygencontaining groups such as carboxyl or lactone groups on the modified ACF, which is consistent with the results based on XPS.
炭/炭复合材料的结构对磁电阻----位向曲线形状的影响
DENG Hai-jin, LI Jun-hong, SUN Li, LI Ming
2006, 21(03): 213-218.
Abstract(2980) PDF(1909)
Abstract:
The magnetoresistance(MR)orientation angle (φ) relationship of four C/C composites, each with a different texture and graphitized at heat treatment temperature (HTT) between 2400 and 2800℃,were investigated. The shape of the MR-φ curve varied with the texture of the C/C composite materials. However, this shape is not affected by HTT, test temperature and the magnetic field intensity. Fourier analysis was applied to each MR-φ curve, indicating that the shape of the MR-φ curve is related to the direction of the fibers in the C/C composites.
酚醛树脂基活性炭微球的电化学性能II.作为EDLC电极材料的活性炭微球的制备及电化学性能
WANG Fu-rong, LI Kai-xi, LU Yong-gen, LI Qiang, LU Chun-xiang, SUN Cheng-gong
2006, 21(03): 219-224.
Abstract(2318) PDF(2538)
Abstract:
Phenolic resinbased activated carbon microbeads were used as the electrode materials for electric doublelayer capacitors(EDLC)in an aqueous electrolyte. The electrochemical behavior of the EDLC was investigated by the constant current cycling method. It was found that activated carbon microbeads with high specific capacitance could be prepared by steam activation at 800℃ for 1h using an activating agent containing 40% volume of steam. The obtained activated carbon microbeads had a specific capacitance of 143F/g, and had excellent chargedischarge properties with a cycling efficiency up to 98%. Mesopores of 2-7.5nm had a remarkable influence on specific capacitance.
热处理对各向同性热解炭材料微观结构和力学性能的影响
WU Jungfeng, BAI Shuo, CHENG Huiming
2006, 21(03): 225-230.
Abstract(2973) PDF(3370)
Abstract:
The influence of heat treatment on the microstructure and mechanical properties of isotropic pyrolytic carbon prepared by chemical vapor deposition was studied by TEM, SEM, XRD, polarized light metallography, laser Raman spectroscopy, microhardness and threepoint bend tests. Results show that the interlayer spacing of the pyrolytic carbon decreases and the crystal size increases with increasing heat treatment temperature. At the same time, the microhardness and the elastic modulus decrease with increasing heat treatment temperature. Heat treatment below 2400℃ has no effect on the flexural strength of the isotropic pyrolytic carbon,but its flexural strength increases after graphitization at 2600℃. It is observed that the high temperature heat treatment has changed the pore structure, which consequently influences the mechanical properties.
炭/炭复合材料MoSi2/SiC高温抗氧化复合涂层的制备及其结构
RAN Li-ping, YI Mao-zhong, JIANG Jian-xian, GE Yi-cheng
2006, 21(03): 231-236.
Abstract(2822) PDF(1982)
Abstract:
An appropriately structured gradient coating on the surface of C/C composites, consisting of, from inner to outer, a SiC transiting layer, a SiC compacting layer, a MoSi2/SiC double phase layer and a MoSi2containing outer layer, was prepared by a twostage coating method. As the holding time at high temperature stage is increased, the MoSi2 outer layer becomes more continuous. The adhesion between the coating and the composites is mainly caused by a metallurgical bond and a mechanical bond.The surface of the coating is sealed by Si(OC2H5)4, and SiO2 gel fills the cracks in the coating and covers it. Oxidation of the specimen with an unsealed coating causes mass loss, while the specimen with the sealed coating shows a mass gain in air at 1500℃.
以含模板剂的中孔MCM-41为模板合成类碳纳米管材料
LIU Xian-bin, LIU Zhong-min, CHANG Fu-xiang, QU Li-hong, SANG Shi-yun, ZHANG Yang-yang
2006, 21(03): 237-242.
Abstract(1820) PDF(1817)
Abstract:
A carbon nanotube analog was prepared using the structuredirecting agent cetyltrimetylammonium bromide locked in the channels of MCM41 as a carbon source. The structures and properties of the resulting samples were characterized by powder XRD, nitrogen adsorptiondesorption measurement, TEM and TGA. It was found that the carbon nanotube analog obtained by this method is amorphous. Pretreatment with concentrated sulfuric acid is a key step in its formation.
牵伸石墨化对石墨纤维结构和力学性能的影响
XUE Lin-bing, WANG Hao-jing, LI Dong-feng
2006, 21(03): 243-247.
Abstract(2735) PDF(3272)
Abstract:
The influence of stretching ratio between 02.5% on microstructure and mechanical properties of PANbased graphite fibers was investigated by XRD and mechanical testing for graphitization temperatures of 2400, 2700 and 3000℃. Results show that stretching ratios of 1.25, 1.5 and 2.20% yield a maximum tensile strength of 3.1, 2.55 and 2.25GPa at 2400, 2700 and 3000℃ respectively, and the maximum tensile strength is an increase of about 10-20% compared to the unstretched samples at the same temperature. The elasticity modulus of the graphite fibers increases with stretching ratio at the different temperatures investigated and is 15% larger than that of the unstretched samples at a stretching ratio of 2.5%. The size of crystallites Lc (3.612-7.094nm), La (12.90924.400nm) and orientation degree of crystallites (89.51-92.97%) increase, but d002 (0.3465-0.3418nm) decreases with the stretching. This contributes to the increase of tensile strength and modulus of the graphite fibers.
多壁碳纳米管横向扰动波传播的研究
SHA Feng-huan, ZHAO Long-mao, YANG Gui-tong
2006, 21(03): 248-252.
Abstract(2577) PDF(1655)
Abstract:
A multipleelasticshell model is presented for wave propagation estimation along an individual MWCNT. The analysis shows that when the frequency is lower than the critical frequencies of the shells in MWCNT, the vibration mode is almost coaxial. However, when the frequency is higher than at least one of the critical frequencies, noncoaxial vibration modes emerge and these vibrations propagate at various speeds significantly higher or lower than the speed predicted by the singleelasticshell model. Hence, tetrahertz waves in MWCNTs are essentially noncoaxial with complex phenomena. Tetrahertz waves in MWCNTs propagate at various speeds, which depend not only on the frequency, but also on the noncoaxial vibration mode.
用柔性石墨制备低密度膨胀石墨块
GAO Lin, MA Ling
2006, 21(03): 253-258.
Abstract(2206) PDF(1878)
Abstract:
Low density monolithic expanded graphites were prepared from flexible graphite sheet or plate by soaking the sheet or plate in concentrated sulfuric acid or nitric acid for intercalation and then expanding them at temperatures from 200℃ to 750℃. The effects of the type of intercalating agent, intercalating time and temperature for expansion on bulk density and integrity of the monoliths were investigated. Results show that the higher the expansion temperature, the lower the bulk density, and the more difficult to obtain a monolithic expanded graphite with structural integrity. Monolithic expanded graphites with structural integrity can be obtained using concentrated sulfuric acid or nitric acid as intercalating agent for over 3h at an expansion temperatures of less than 550℃ for the former or less than 650℃ for the latter. Both uniform and nonuniform expansions were found in the monolithic products.
具有优异淋巴示踪特性的纳米炭混悬液的制备
XIE Yong-mei, TANG Xiao-hai, HE Jun, CHENG Ming, ZHENG Kai-bo, ZHANG Yong
2006, 21(03): 259-262.
Abstract(2492) PDF(1966)
Abstract:
Carbon black (CB) was oxidized by concentrated nitric acid at 100℃ for 100h to obtain a CB with excellent lymphatic tracing properties, which were characterized by XPS, alkalimetric titration and a staining test. It is found that nitric acid treatment obviously increases oxygencontaining functional groups on CB surface. The average diameter of the oxidized CB in suspension is 72nm with no agglomeration found after storage at room temperature for 180days. The suspension prepared with the oxidized CB can effectively color the injecting region of lymph nodes in 5min. The staining effect is superior to a commercial available lymphatic tracer named Carbon Nanoparticle Suspension Injection.
纳米SiO2改性乳液上浆剂对炭纤维抗拉强度的影响
YANG Yu, LU Chun-xiang, WANG Xin-kui, SU Xiao-lei, HE Fu, LI Yong-hong, SONG Yan
2006, 21(03): 263-268.
Abstract(2502) PDF(1749)
Abstract:
The influence of a nanoSiO2 modified sizing on the tensile strength of carbon fibers was studied by SEM and Xray energy dispersion spectrum tester (EDS). The tensile strength of the resulting carbon fibers was analyzed by the Weibull method. Results showed that when the ratio of SiO2 nanoparticles to epoxy resin was 0.5 w/%,the fiber strength reached a maximum value, 10.1% larger than that of the unsized carbon fibers, and the Weibull parameter exhibited a maximum, indicating a minimum distribution of tensile strength. EDS indicated that the content of elemental Si increased on the surfaces of the sized carbon fibers with nanoSiO2/epoxy emulsion. The sized fibers surfaces were even and the surface grooves were shallow, compared to unsized fibers. However, the fracture crosssections of the sized fibers were concave or convex, indicating a tough fracture character.
氧化处理方法与多壁碳纳米管表面羧基含量的关系
QIU Jun, WANG Guo-jian, QU Ze-hua, Chang Lu
2006, 21(03): 269-272.
Abstract(4141) PDF(5894)
Abstract:
Carboxylic groups were produced on the surface of MWCNTs by oxidation treatment. Carboxylic group contents were quantitively analyzed by FTIR, TGA and XPS. Results show that TGA and XPS analysis give similar carboxylic group contents on the surface of MWCNTs. For 2.5mol/L nitric acid oxidation for 4h, mixed acid oxidation for 4h, and mixed acid oxidation for 4h and then 20% H2O2 oxidation for 2h, 4.80, 5.35 and 7.55mol% of carboxylic groups on the were respectively produced.
CVD法制备纳米石墨棒
XU Xiang-ju, YU Yue-li, XIA Xiao-hong, JIA Zhi-jie
2006, 21(03): 273-273.
Abstract(2823) PDF(3906)
Abstract:

Graphite nanorods were prepared by chemical vapor deposition of methane at temperatures from 865℃ to 930℃ using a Fe based catalyst, and were characterized by XRD, TEM and Raman spectroscopy. Results indicate that the product consists of high purity graphite nanorods with average diameters around 16.3nm and lengths from 200nm to 800nm.

氮化碳晶体的研究进展
Ma Zhi-bin
2006, 21(03): 277-284.
Abstract(2055) PDF(1781)
Abstract:

Progress and key difficulties in the synthesis and characterization of carbon nitride crystals are summarized. It could be concluded that there is no definite evidence and effective method for synthesizing a carbon nitride crystal. The main problems in the high temperature and high pressure method are the choice and preparation of the precursor materials and the effective control of thermodynamic parameters during the high pressure processing. For the plasma CVD method, the substrate atom, especially silicon, plays an important role in the synthesis of a carbon nitride crystal. The difficulties needed to be resolved using the ion beam sputtering method are how to increase nitrogen concentration in the reactants at a lower substrate temperature and to find synthesis conditions to form a high concentration of sp3C-N single bonds. Electrochemical methods can effectively reduce the activation energy and deposition temperature by using precursors containingC-N single bonds, but the problems are how to promote crystallization of the deposits and to decrease the amount of byproducts. Combined application of the above mentioned methods may be effective in the synthesis of carbon nitride crystals.

炭材料科学的研究现状和发展趋势——Carbon 2006参会感
Lu An-hui
2006, 21(03): 285-288.
Abstract(2560) PDF(2946)
Abstract:
The International Carbon conference, Carbon 2006, was held in Aberdeen, Scotland, hosted by the British Carbon Group, from July 1621 2006. Over 500 participants attended. All together 605 articles were accepted for discussion on the following topics: Adsorption (Fundamentals, Applications), Activated carbon, Biological applications, Carbon fibres, Carbonization, Mesophase, Pyrolysis and Thermal processes, C/C composite materials, Diamond, Environmental applications, Fullerenes, Nanotubes and Nanoforms (Fundamentals, Applications, Theory), Electrical, battery and related applications, Industrial & energy products, Intercalation, Nuclear graphite, Physical & chemical properties, Reactivity and catalysis, Special forms of carbon. Five plenary lectures were given. They were "Architecture in nanospace", "Adsorption on carbon materials", "Carbon nanotubes", "Graphitic materials", and "Modeling of graphite and nanotubes". Compared to previous carbon conferences, much attention was paid to energyrelated materials, environmental protection and biological applications.