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New Carbon Materials, 2006, 21(3)-Abstracts
Carbon 45 (2007) 690–694 www.elsevier.com/locate/carbon
New Carbon Materials, 2006, 21(3)—Abstracts
Preparation, structures and properties of mesophase pitch-based carbon foams by Zeng-min Shen, Min Ge, Wei-dong Chi, Hui Liu Institute of Carbon Fibers and Composites, Beijing University of Chemical Technology, Beijing 100029, China 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 C and 2300–2800 C 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). [New Carbon Materials, 2006, 21(3):193–201] Preparation and magnetic properties of carbon encapsulated iron nanocapsules from starch by Jie-shan Qiu*,**, Yu-feng Sum*, Ying Zhou*,**, Tian-jun Sun*, Qi-xiu Li* *Carbon Research Laboratory, School of Chemical Engineering, Center for Nanomaterials and Science, State Key Lab of Fine Chemicals, Dalian University of Technology, Dalian 116012, China **Key Laboratory for Micro/Nano Technology and System of Liaoning Province, Dalian University of Technology, Dalian 116023, China 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 asobtained 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 doi:10.1016/j.carbon.2006.09.008
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. [New Carbon Materials, 2006, 21(3):202–205] Chemical structure modification of activated carbon fibers by cerous nitrate by Shui-xia Chen, Jian-liang Chen, Qing-yu Wu Materials Science Institute, School of Chemistry and Chemical Engineering, Zhongshan University, Guangzhou 510275, China 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. [New Carbon Materials, 2006, 21(3):206–212] Influence of texture of C/C composites on the shape of magnetoresistance-orientation angles curves by Hai-jin Deng*, Jun-hong Li**, Sun Li*, Ming Li* *Department of Material Science & Engineering, Tsinghua University, Beijing 100084 China
New Carbon Materials, 2006, 21(3)—Abstracts / Carbon 45 (2007) 690–694
**Institute of Mech. & Electro. Engineering, Nanchang University, Nanchang 330029, China The magnetoresistance(MR)-orientation angle (F) relationship of four C/C composites, each with a different texture and graphitized at heat treatment temperature (HTT) between 2400 and 2800 C, were investigated. The shape of the MR-F 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-F curve, indicating that the shape of the MR-F curve is related to the direction of the fibers in the C/C composites. [New Carbon Materials, 2006, 21(3):213–218]
The electrochemical performance of phenolic resin-based activated carbon microbeads II preparation and electrochemical performance of activated carbon microbeads as the electrode materials of EDLC by Fu-rong Wang*,**, Kai-xi Li*, Yong-gen Lu*, Qiang Li*, Chun-xiang Lu*, Cheng-gong Sun*** *Key Laboratory of Carbon Materials, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, China **Graduate School of the Chinese Academy of Sciences, Beijing 100039, China ***School of Chemical, Environmental and Mining Engineering, University of Nottingham, University Park, Nottingham, NG7 2RD, UK 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 C for 1h using an activating agent containing 40% volume of steam. The obtained activated carbon microbeads had a specific capacitance of 143 F/g, and had excellent charge–discharge properties with a cycling efficiency up to 98%. Mesopores of 2–7.5 nm had a remarkable influence on specific capacitance. [New Carbon Materials, 2006, 21(3):219–224]
Influence of heat treatment on microstructure and mechanical properties of isotropic pyrolytic carbon by Jung-feng Wu, Shuo Bai, Hui-ming Cheng Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
691
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 2400 C has no effect on the flexural strength of the isotropic pyrolytic carbon,but its flexural strength increases after graphitization at 2600 C. It is observed that the high temperature heat treatment has changed the pore structure, which consequently influences the mechanical properties. [New Carbon Materials, 2006, 21(3):225–230]
Preparation and structure of a MoSi2/SiC high temperature anti-oxidative gradient coating for carbon/carbon composites by Li-ping Ran, Mao-zhong Yi, Jian-xian Jiang, Yi-cheng Ge State Key Laboratory for Power Metallurgy, Central South University, ChangSha, 410083, China 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 C. [New Carbon Materials, 2006, 21(3):231–236]
Preparation of a carbon nanotube analog from surfactantcontaining MCM-41 silica by Xian-Bin Liu*,**, ZhongMin Liu*, Fu-Xiang Chang*,**, Li-Hong Qu*,**, Shi-Yun Sang*,**, Yang-Yang Zhang*,** *Dalian Institute of Chemical Physics, The Chinese Academy of Sciences, Dalian 116023, LiaoNing, China **Graduate School of the Chinese Academy of Science, Beijing 100039, China A carbon nanotube analog was prepared using the structure-directing agent cetyltrimetylammonium bromide
692
New Carbon Materials, 2006, 21(3)—Abstracts / Carbon 45 (2007) 690–694
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 adsorptiondesorption 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.
than the speed predicted by the single-elastic-shell model. Hence, tetra-hertz waves in MWCNTs are essentially noncoaxial 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. [New Carbon Materials, 2006, 21(3):248–252]
[New Carbon Materials, 2006, 21(3):237–242]
Effect of stress graphitization on the microstructure and mechanical properties of graphite fibers by Lin-bing Xue*,**, Hao-jing Wang*, Dong-feng Li *Key Laboratory of Carbon Materials, Institute Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, China **Graduate School of the Chinese Academy of Sciences, Beijing 100039, China 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 C. Results show that stretching ratios of 1.25, 1.5 and 2.20% yield a maximum tensile strength of 3.1, 2.55 and 2.25 GPa at 2400, 2700 and 3000 C 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. [New Carbon Materials, 2006, 21(3):243–247] Prediction of wave propagation in multi-walled carbon nanotubes examined using a multiple-elastic-shell model by Feng-huan Sha, Long-mao Zhao, Gui-tong Yang Institute of Applied Mechanics, Taiyuan University of Technology, Taiyuan 030024, China 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, noncoaxial vibration modes emerge and these vibrations propagate at various speeds significantly higher or lower
Preparation of low density monolithic expanded graphite from flexible graphite by Lin Gao*, Ling Ma** *College of Chemistry and Environmental Engineering, Yangtze University, Jingzhou 434000, China **College of Medical Science,Yangtze University, Jingzhou 434000, China 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 C. 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 C for the former or less than 650 C for the latter. Both uniform and nonuniform expansions were found in the monolithic products. [New Carbon Materials, 2006, 21(3):253–258]
Preparation of carbon nanoparticle suspension with excellent lymphatic tracing properties by Yong-mei Xie*, Xiao-hai Tang**, Jun He*, Ming Cheng*, Kai-bo Zheng*, Yong Zhang** *College of Chemistry, Sichuan University, Chengdu 610064, China **Chengdu Pharmmate Technology Co., Ltd., No. 23, Gaopeng Dadao, Gaoxin District, Chengdu 610041, China Carbon black (CB) was oxidized by concentrated nitric acid at 100 C for 100 h 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 72 nm with no agglomeration found after storage at room temperature for 180 days. The suspension prepared with the oxidized CB
New Carbon Materials, 2006, 21(3)—Abstracts / Carbon 45 (2007) 690–694
can effectively color the injecting region of lymph nodes in 5 min. The staining effect is superior to a commercial available lymphatic tracer named Carbon Nanoparticle Suspension Injection. [New Carbon Materials, 2006, 21(3):259–262] Effect of a nano-SiO2 modified emulsion sizing on the strength of carbon fibers by Yu Yang*,**, Chun-xiang Lu*,**, Xin-kui Wang*, Xiao-lei Su*,**, Fu He*, Yonghong Li*, Yan Song* *Key Laboratory of Carbon Materials, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, China **Graduate University of the Chinese Academy of Sciences, Beijing 100039, China 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-SiO2/epoxy emulsion. The sized fibers surfaces were even and the surface grooves were shallow, compared to unsized fibers. However, the fracture crosssections of the sized fibers were concave or convex, indicating a tough fracture character. [New Carbon Materials, 2006, 21(3):263–268] Relationship between oxidation treatment method and carboxylic group content on the surface of MWCNTs by Jun Qiu, Guo-jian Wang, Ze-hua Qu, and Lu Chang College of Material Science and Engineering, Tongji University, Shanghai 200092, China 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 2.5 mol/L nitric acid oxidation for 4 h, mixed acid oxidation for 4 h, and mixed acid oxidation for 4 h and then 20% H2O2 oxidation for 2 h, 4.80, 5.35 and 7.55 mol% of carboxylic groups on the were respectively produced. [New Carbon Materials, 2006, 21(3):269–272]
693
Synthesis of graphite nanorods by CVD by Xiang-ju Xu, Yue-li Yu, Xiao-hong Xia, Zhi-jie Jia Institute of Nano-science and Technology, Central China Normal University, Wuhan 430079, China Graphite nanorods were prepared by chemical vapor deposition of methane at temperatures from 865 to 930 C 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 16.3 nm and lengths from 200 to 800 nm. [New Carbon Materials, 2006, 21(3):273–276]
Progress in the synthesis and characterization of carbon nitride crystals by Zhi-bin Ma Key Laboratory of Plasma Chemistry and Advanced Materials, School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan 430073, China 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 containing C–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. [New Carbon Materials, 2006, 21(3):277–284]
A brief overview on the Carbon 2006 Conference by An-Hui Lu Max-Planck-Institut fu¨r Kohlenforschung, 45470 Mu¨lheim an der Ruhr, Germany The International Carbon conference, Carbon 2006, was held in Aberdeen, Scotland, hosted by the British Carbon
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New Carbon Materials, 2006, 21(3)—Abstracts / Carbon 45 (2007) 690–694
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 & che-
mical 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. [New Carbon Materials, 2006, 21(3):285–288]
New Carbon Materials, 2006, 21(3)—Abstracts
Preparation, structures and properties of mesophase pitch-based carbon foams by Zeng-min Shen, Min Ge, Wei-dong Chi, Hui Liu Institute of Carbon Fibers and Composites, Beijing University of Chemical Technology, Beijing 100029, China 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 C and 2300–2800 C 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). [New Carbon Materials, 2006, 21(3):193–201] Preparation and magnetic properties of carbon encapsulated iron nanocapsules from starch by Jie-shan Qiu*,**, Yu-feng Sum*, Ying Zhou*,**, Tian-jun Sun*, Qi-xiu Li* *Carbon Research Laboratory, School of Chemical Engineering, Center for Nanomaterials and Science, State Key Lab of Fine Chemicals, Dalian University of Technology, Dalian 116012, China **Key Laboratory for Micro/Nano Technology and System of Liaoning Province, Dalian University of Technology, Dalian 116023, China 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 asobtained 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 doi:10.1016/j.carbon.2006.09.008
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. [New Carbon Materials, 2006, 21(3):202–205] Chemical structure modification of activated carbon fibers by cerous nitrate by Shui-xia Chen, Jian-liang Chen, Qing-yu Wu Materials Science Institute, School of Chemistry and Chemical Engineering, Zhongshan University, Guangzhou 510275, China 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. [New Carbon Materials, 2006, 21(3):206–212] Influence of texture of C/C composites on the shape of magnetoresistance-orientation angles curves by Hai-jin Deng*, Jun-hong Li**, Sun Li*, Ming Li* *Department of Material Science & Engineering, Tsinghua University, Beijing 100084 China
New Carbon Materials, 2006, 21(3)—Abstracts / Carbon 45 (2007) 690–694
**Institute of Mech. & Electro. Engineering, Nanchang University, Nanchang 330029, China The magnetoresistance(MR)-orientation angle (F) relationship of four C/C composites, each with a different texture and graphitized at heat treatment temperature (HTT) between 2400 and 2800 C, were investigated. The shape of the MR-F 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-F curve, indicating that the shape of the MR-F curve is related to the direction of the fibers in the C/C composites. [New Carbon Materials, 2006, 21(3):213–218]
The electrochemical performance of phenolic resin-based activated carbon microbeads II preparation and electrochemical performance of activated carbon microbeads as the electrode materials of EDLC by Fu-rong Wang*,**, Kai-xi Li*, Yong-gen Lu*, Qiang Li*, Chun-xiang Lu*, Cheng-gong Sun*** *Key Laboratory of Carbon Materials, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, China **Graduate School of the Chinese Academy of Sciences, Beijing 100039, China ***School of Chemical, Environmental and Mining Engineering, University of Nottingham, University Park, Nottingham, NG7 2RD, UK 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 C for 1h using an activating agent containing 40% volume of steam. The obtained activated carbon microbeads had a specific capacitance of 143 F/g, and had excellent charge–discharge properties with a cycling efficiency up to 98%. Mesopores of 2–7.5 nm had a remarkable influence on specific capacitance. [New Carbon Materials, 2006, 21(3):219–224]
Influence of heat treatment on microstructure and mechanical properties of isotropic pyrolytic carbon by Jung-feng Wu, Shuo Bai, Hui-ming Cheng Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
691
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 2400 C has no effect on the flexural strength of the isotropic pyrolytic carbon,but its flexural strength increases after graphitization at 2600 C. It is observed that the high temperature heat treatment has changed the pore structure, which consequently influences the mechanical properties. [New Carbon Materials, 2006, 21(3):225–230]
Preparation and structure of a MoSi2/SiC high temperature anti-oxidative gradient coating for carbon/carbon composites by Li-ping Ran, Mao-zhong Yi, Jian-xian Jiang, Yi-cheng Ge State Key Laboratory for Power Metallurgy, Central South University, ChangSha, 410083, China 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 C. [New Carbon Materials, 2006, 21(3):231–236]
Preparation of a carbon nanotube analog from surfactantcontaining MCM-41 silica by Xian-Bin Liu*,**, ZhongMin Liu*, Fu-Xiang Chang*,**, Li-Hong Qu*,**, Shi-Yun Sang*,**, Yang-Yang Zhang*,** *Dalian Institute of Chemical Physics, The Chinese Academy of Sciences, Dalian 116023, LiaoNing, China **Graduate School of the Chinese Academy of Science, Beijing 100039, China A carbon nanotube analog was prepared using the structure-directing agent cetyltrimetylammonium bromide
692
New Carbon Materials, 2006, 21(3)—Abstracts / Carbon 45 (2007) 690–694
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 adsorptiondesorption 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.
than the speed predicted by the single-elastic-shell model. Hence, tetra-hertz waves in MWCNTs are essentially noncoaxial 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. [New Carbon Materials, 2006, 21(3):248–252]
[New Carbon Materials, 2006, 21(3):237–242]
Effect of stress graphitization on the microstructure and mechanical properties of graphite fibers by Lin-bing Xue*,**, Hao-jing Wang*, Dong-feng Li *Key Laboratory of Carbon Materials, Institute Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, China **Graduate School of the Chinese Academy of Sciences, Beijing 100039, China 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 C. Results show that stretching ratios of 1.25, 1.5 and 2.20% yield a maximum tensile strength of 3.1, 2.55 and 2.25 GPa at 2400, 2700 and 3000 C 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. [New Carbon Materials, 2006, 21(3):243–247] Prediction of wave propagation in multi-walled carbon nanotubes examined using a multiple-elastic-shell model by Feng-huan Sha, Long-mao Zhao, Gui-tong Yang Institute of Applied Mechanics, Taiyuan University of Technology, Taiyuan 030024, China 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, noncoaxial vibration modes emerge and these vibrations propagate at various speeds significantly higher or lower
Preparation of low density monolithic expanded graphite from flexible graphite by Lin Gao*, Ling Ma** *College of Chemistry and Environmental Engineering, Yangtze University, Jingzhou 434000, China **College of Medical Science,Yangtze University, Jingzhou 434000, China 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 C. 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 C for the former or less than 650 C for the latter. Both uniform and nonuniform expansions were found in the monolithic products. [New Carbon Materials, 2006, 21(3):253–258]
Preparation of carbon nanoparticle suspension with excellent lymphatic tracing properties by Yong-mei Xie*, Xiao-hai Tang**, Jun He*, Ming Cheng*, Kai-bo Zheng*, Yong Zhang** *College of Chemistry, Sichuan University, Chengdu 610064, China **Chengdu Pharmmate Technology Co., Ltd., No. 23, Gaopeng Dadao, Gaoxin District, Chengdu 610041, China Carbon black (CB) was oxidized by concentrated nitric acid at 100 C for 100 h 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 72 nm with no agglomeration found after storage at room temperature for 180 days. The suspension prepared with the oxidized CB
New Carbon Materials, 2006, 21(3)—Abstracts / Carbon 45 (2007) 690–694
can effectively color the injecting region of lymph nodes in 5 min. The staining effect is superior to a commercial available lymphatic tracer named Carbon Nanoparticle Suspension Injection. [New Carbon Materials, 2006, 21(3):259–262] Effect of a nano-SiO2 modified emulsion sizing on the strength of carbon fibers by Yu Yang*,**, Chun-xiang Lu*,**, Xin-kui Wang*, Xiao-lei Su*,**, Fu He*, Yonghong Li*, Yan Song* *Key Laboratory of Carbon Materials, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, China **Graduate University of the Chinese Academy of Sciences, Beijing 100039, China 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-SiO2/epoxy emulsion. The sized fibers surfaces were even and the surface grooves were shallow, compared to unsized fibers. However, the fracture crosssections of the sized fibers were concave or convex, indicating a tough fracture character. [New Carbon Materials, 2006, 21(3):263–268] Relationship between oxidation treatment method and carboxylic group content on the surface of MWCNTs by Jun Qiu, Guo-jian Wang, Ze-hua Qu, and Lu Chang College of Material Science and Engineering, Tongji University, Shanghai 200092, China 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 2.5 mol/L nitric acid oxidation for 4 h, mixed acid oxidation for 4 h, and mixed acid oxidation for 4 h and then 20% H2O2 oxidation for 2 h, 4.80, 5.35 and 7.55 mol% of carboxylic groups on the were respectively produced. [New Carbon Materials, 2006, 21(3):269–272]
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Synthesis of graphite nanorods by CVD by Xiang-ju Xu, Yue-li Yu, Xiao-hong Xia, Zhi-jie Jia Institute of Nano-science and Technology, Central China Normal University, Wuhan 430079, China Graphite nanorods were prepared by chemical vapor deposition of methane at temperatures from 865 to 930 C 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 16.3 nm and lengths from 200 to 800 nm. [New Carbon Materials, 2006, 21(3):273–276]
Progress in the synthesis and characterization of carbon nitride crystals by Zhi-bin Ma Key Laboratory of Plasma Chemistry and Advanced Materials, School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan 430073, China 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 containing C–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. [New Carbon Materials, 2006, 21(3):277–284]
A brief overview on the Carbon 2006 Conference by An-Hui Lu Max-Planck-Institut fu¨r Kohlenforschung, 45470 Mu¨lheim an der Ruhr, Germany The International Carbon conference, Carbon 2006, was held in Aberdeen, Scotland, hosted by the British Carbon
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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 & che-
mical 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. [New Carbon Materials, 2006, 21(3):285–288]