新型炭材料

ZHOU Xin-hong, CUI Guang-lei, ZHI Lin-jie, ZHANG Shu-sheng

2007, 22(01): 1-6.

Abstract(2389)

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Abstract:
Large-area helical carbon microcoils were prepared over metal surfaces by the copper-catalyzed pyrolysis of acetylene. The copper catalyst was formed on the metal surface by the electrochemical oxidation of a catalytic precursor (copper tartrate). The coils were characterized by SEM, FT-IR, XPS, and contact angle measurements. It was found that the coils had intrinsic chemical stability and were superhydrophobic over a wide range of pH values from 1 to 14. It is considered that such materials can be used as special interfacial functional materials.

锂在人造石墨、中间相炭微球及无定形碳中的扩散系数(英文)

GUO Hua-jun, LI Xin-hai, ZHANG Xin-ming, WANG Hong-qiang, WANG Zhi-xing, PENG Wen-jie

2007, 22(01): 7-11.

Abstract(2458)

PDF(1775)

Abstract:
The structures of pyrolytic sugar carbon, resin carbon, artificial graphite, and mesocarbon microbeads (MCMBs) and the diffusion coefficient of lithium in them were determined by X-ray diffraction and potential step chronoamperometry measurements. It was found that the diffusion coefficient of lithium was strongly dependent on the degree of discharge and the structure of the carbon anodes. As the discharge degree increased, the diffusion coefficient of lithium in MCMB anodes decreased from 4.43×10-9 cm2/s to 5.24×10-10 cm2/s. At half discharge, the diffusion coefficients of lithium in sugar carbon, resin carbon, artificial graphite, and MCMB anode were 1.4×10-10 cm2/s, 5.75×10-10 cm2/s, 1.24×10-9 cm2/s, 2.1×10-9 cm2/s, respectively, showing that diffusion of lithium in soft carbons (artificial graphite and MCMBs) was much easier than in hard carbons such as sugar and resin carbon.

一种新型C/C复合材料——石墨粉增强热解炭

ZHAO Jian-guo, LI Ke-zhi, LI He-jun

2007, 22(01): 12-16.

Abstract(4248)

PDF(1800)

Abstract:
Graphite powder reinforced pyrocarbon (G/C) was prepared by thermal gradient chemical vapor infiltration technology. The microstructures and basic properties of the G/C were investigated by polarized light microscopy, SEM, electrical and mechanical tests. It is found that pyrocarbon enwraps the graphite powder particles and fills the pores between them effectively. The G/C is isotropic, has a density of 1.85g/cm3, and has a higher volume resistivity (148.4μΩ·m) than graphite and the other C/C composites. It has excellent mechanical properties with a flexural strength of 50MPa and a compressive strength of 120MPa, twice those of pure graphite. The compressive strength of the G/C is similar to, and the flexural strength is lower than, those of carbon felt/pyrocarbon composites.

硝苯地平在球状活性炭中的吸附及缓释行为

LU Chun-xiang, LING Li-cheng, YUAN Shu-xia, LIANG Dong, LI Yong-hong

2007, 22(01): 17-22.

Abstract(2161)

PDF(1396)

Abstract:
Adsorption of nifedipine by spherical activated carbons (SACs) and their invitro release behavior were investigated. The pore structure, specific surface area and surface morphologies of the SACs were tested by N2 adsorption and SEM. The relationship between pore structure, specific surface area and adsorption/in-vitro release behavior was discussed. Results indicated that SACs with a high specific surface area and abundant mesopores ranging between 2nm and 5nm exhibited excellent adsorption and in-vitro release of nifedipine. The maximum adsorption capacity was 19.5mg/g, and the total release rate can reach 19.20%. The release dynamics of SACs containing nifedipine are in accordance with the Higuchi model, which shows that the release speed is a constant.

2D-C/C复合材料及其石墨化制品烧蚀特性分析

TANG Su-fang, WANG Dao-ling, DENG Jing-yi, DU Hai-feng, LIU Wen-chuan, YANG Ke

2007, 22(01): 23-27.

Abstract(3038)

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Abstract:
2D-C/C composites were prepared by pyrocarbon deposition at 1000－1100℃ using liquefied petroleum gas as the carbon source and a 2D carbon fiber weave as substrate. Graphitized samples were obtained by heat treatment at 2800℃ for 10h. An engine torch test was used to evaluate the ablation properties of the two kinds of composites. A comparison of the pore size distribution, the cohesion strength between matrix and fiber, and the thermal conductivity of the two composites was used to explain their ablation characteristics and mechanism. Results show that for the 2D-C/C composites, the ablation mechanism is controlled by a thermo-chemical reaction (oxidation), the ablated surface is even and the ablation rate is 0.033mm/s because of its low porosity, large cohesion strength and low out-of-plane thermal conductivity. For the graphitized 2D-C/C composites, the ablation mechanism is dominated by both oxidation and mechanical wearing with a few macroscopic pits on the ablated surface and the ablation rate is 0.046mm/s, which is caused by their large porosity and low cohesion strength.

煤种对蜂窝状活性炭性能的影响

LIU Lai-shuan, LIU Zhen-yu, HUANG Zhang-gen, LIU Zeng-hou

2007, 22(01): 28-34.

Abstract(2153)

PDF(1321)

Abstract:
Activated carbon honeycombs (ACHs) were prepared by extrusion of honeycombs from a mixture of coal, coal tar, bean oil, methylcellulose and water, followed by carbonization and steam activation. Three Chinese coals, Qujing, Shenfu and Datong, were used as carbon precursors. The ACH monoliths obtained were characterized by N2 adsorption，thermogravimetry and compression tests. Results show that both coal rank and activation time have great a impact on the pore size distribution and mechanical strength. The ACHs from Datong obtained under optimum conditions have the highest BET surface area(884m2/g), the highest ignition temperature (535℃) and the highest mechanical strength(＞13MPa) among the three coals. The mechanical strength of the ACH monoliths decreases with increasing macropore volume. The ignition temperature is hardly affected by ash content but decreases with increasing volatile content.

低温CoCl2催化热处理中间相炭微球用作锂离子电池负极材料

ZHANG Yong-gang, WANG Cheng-yang, YAN Pei

2007, 22(01): 35-39.

Abstract(2553)

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Abstract:
Anode materials for Li-ion secondary batteries were prepared by treating mesocarbon microbeads (MCMBs) in presence of CoCl2 at a temperature below 1000℃. They were characterized by Raman spectroscopy and X-ray diffraction. Results indicated that the heat treated samples belonged to low temperature carbons, but micro-crystals on the surface of the treated MCMBs became ordered. The reversible discharge capacity of the MCMBs was significantly improved, the coulombic efficiency was increased from 52.2％ to 86.7％, and the cycling performance became better. These improvements were ascribed to the ordered structure on the surface of the treated samples that tended to prevent the electrolyte molecules from penetrating into the inside of the MCMBs, and as a result, reduced the irreversible electrochemical reactions.

非晶金刚石膜在口腔医学材料中的应用

SUN Yan, YAO Yue-ling, ZHU Xiao-yu, ZHANG Dong-mei, CHEN Gang, ZHONG Ke, LI Yong-jun

2007, 22(01): 40-46.

Abstract(2193)

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Abstract:
The biocompatibility and surface characteristics of dental materials surfacemodified by an amorphous diamond film were investigated. The dental materials are poly(methyl methacrylate) (PMMA) and pure titanium and the amorphous diamond film surface was produced by a plasma assisted cathode arc discharge under vacuum. The biocompatibility was evaluated by cell cultivation and animal implants and the wearability of the PMMA tooth after modification was analyzed by a scratching test. The surface characteristics of the film were characterized by SEM. The corrosion resistance of the surface of pure titanium dental material after the surface modification was investigated by the electrochemical analysis of a simulated oral cavity filled with artificial saliva. Results show that the toxicity of the amorphous diamond film modified dental materials is zero, and the hemolysis ratio is 3.08%. After polarization pretreatment, the PMMA artificial tooth coated with an amorphous diamond film has a maximium adhesion force of 10.86±0.79N. The selfcorrosive potential and the overpassivation potential of the pure titanium after the surface modification were increased. These results demonstrate that coating the surface of dental materials with a diamond film meets the requirements of biocompatibility, anticorrosion and adhesion strength.

催化处理Lyocell纤维在热解过程中的结构与性能变化

WU Qi-lin, GONG Jing-hua, ZHANG Zhi-hai, PAN Ding

2007, 22(01): 47-52.

Abstract(2719)

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Abstract:
Changes in the structure and mechanical properties during the conversion of lyocell precursors to carbon fibers were investigated by scanning electron microscopy, wide angle X-ray diffraction and small angle Xray scattering when they were treated with a catalyst containing sulfuric acid and carbamide. It was found that the density of fibers first increased with temperature, then decreased when the temperature exceeded 200℃. The strength decreased gradually and was close to zero between 150℃ and 200℃, but then increased with increasing temperature. The degree of polymerization showed similar changes to the strength changes during pyrolysis. The crystalline structure of the cellulose II crystals in lyocell fibers was converted to a 2D turbostratic carbon structure.

炭钌复合电极碱性电化学电容器的研究(英文)

SU Yue-feng, WU Feng, BAO Li-ying, YANG Zhao-hui

2007, 22(01): 53-58.

Abstract(2059)

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Abstract:
Hydrous ruthenium oxide was synthesized by a solgel method on the surface of activated carbon (AC). After heat treatment at 150℃, the RuO2/AC composite was used as a positive electrode material in an alkaline electrochemical capacitor. Several composites with different Ru content were prepared and studied. It was found that the composite containing 30w/% Ru had a specific capacitance of about 333F/g at a low current density, whereas that of the pure AC was only about 241F/g. With an increase of Ru content, the specific capacitance of the electrode increased correspondingly. When the Ru content exceeded 10w/%, the specific capacitance contributed by RuO2·xH2O was about 440F/g. The performance of the composite under the condition of high rate discharge was as good as that of the AC electrode.

T300和T700炭纤维的结构与性能

LI Dong-feng, WANG Hao-jing, HE Fu, WANG Xin-kui

2007, 22(01): 59-64.

Abstract(2718)

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Abstract:
The microstructures of T300 and T700 carbon fibers were investigated by scanning electron microscopy, elemental analysis, X-ray diffraction and Raman spectroscopy. Results showed that the surface of T700 was smooth, whereas ridge-like prominences and grooves were much more obvious on the surface of the T300 fibers, indicating that the former were produced by dry-jet wet spinning and the latter by wet spinning. Grain-like features were seen in the cross section areas of both fibers. T700 fibers had a higher carbon content and less nitrogen than did T300 fibers. The difference in microstructure parameters, such as d002、La and Lc, showed that the heat treatment temperature of T700 during manufacture was higher than that of T300. Compared with T300, the preferred orientation parameter Z of T700 fibers was 2.3° lower, the density 2.27% higher and the microvoid volume 7.54% less. Thus it is the densification that produces the higher tensile strength for T700 fibers.

酚醛-糠醛基炭气凝胶对NaCl溶液的电吸附行为

WANG Wan-bing, ZHANG Rui, LIU Xi-miao, WANG Chan, LING Li-cheng

2007, 22(01): 65-69.

Abstract(2403)

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Abstract:
Electrosorption of NaCl aqueous solution by phenolicfurfural based carbon aerogel (CA) was performed in a static electrosorption apparatus by applying an electric potential via a potentiostat. The effect of NaCl concentration, thickness of CA electrode and applied potential on the electrosorption capacity of the CA was investigated. It was found that electrosorption capacity increased with increasing NaCl concentration with an obvious electric field overlapping effect observed in small pores at low concentration. With increasing electric potential from 0.6-2.0V, electrosorption capacity increased dramatically below 1.5V then leveled off above 1.5V. With increasing CA electrode thickness from 0.5-1.5mm, the electrosorption capacity decreased monotonically as a result of the electric field distribution along the width of the electrode. The maximum electrosorption capacity of CA was 12.7mg/g at a potential of 1.2V and an electrode thickness of 0.5mm. A high performance electrode for electrosorption should have a large amount of mesopores and be as thin as possible.

低碳钢基体表面氧乙炔碳化焰法沉积纳米炭纤维(英文)

LEI Shu-mei, KUANG Tong-chun, CHENG Xiao-ling, YIN Shi-heng, ZHU Hong-mei

2007, 22(01): 70-74.

Abstract(2802)

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Abstract:
Carbon nanofiber (CNF) coatings were successfully deposited on a low carbon steel substrate that was pretreated by concentrated nitric acid using an oxyacetylene reducing flame. The morphologies and the microstructures of the CNF coatings were characterized using scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. The CNFs were compact, entangled with each other, and highly graphitized with diameters from 80 to 100nm and lengths from 3 to 5μm. They tended peel off the substrate because of a weak adhesion strength. Iron oxide particles were produced on the pretreated low carbon steel substrate surface in the flame, and these acted as growth catalysts for the CNFs.

前驱体对炭泡沫孔结构的影响(英文)

MIN Zhen-hua, CAO Min, ZHANG Shu, WANG Xiu-dan, WANG Yong-gang

2007, 22(01): 75-79.

Abstract(2471)

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Abstract:
Carbon foams were prepared from coal tar pitch, petroleum mesophase pitch, and AR pitch. The molecular weights of the precursors were determined by gel permeation chromatography. Foam structure, average pore diameter and pore diameter distribution were investigated by scanning electron and optical microscopy. It was found that coal tar pitch could not be used as-received to prepare useful carbon foams because of their higher quinoline insoluble (QI) fraction. The carbon foams with homogeneous open pores and microscopic domains were obtained from AR pitch and petroleum mesophase pitch. Carbon foams prepared from AR pitch exhibited a smaller average pore diameter (212μm), thinner cell walls, a narrower pore diameter distribution (180-300μm), higher opencell ratio, and better ligaments compared with those from the other pitches. It is concluded that a precursor with low molecular weight, narrow molecular weight distribution, and low QI content is favorable for the preparation of carbon foams.

壳状碳纳米颗粒的制备和分散

XIE Hua-qing

2007, 22(01): 80-83.

Abstract(2149)

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Abstract:
Carbon nanoshells (CNSs) were produced by CO2 laser irradiated pyrolysis of C2H2 in a continuous process. Hydrophilic functional groups were introduced onto the surface of the CNSs by treatment with a mixture of boiling nitric and hydrochloric acids to improve their dispersive characteristics. TEM, XRD, FTIR, and zeta potential analysis were used to characterize the CNSs and the treated CNSs. Results showed that oxygen-containing functional groups were formed on the surface of the treated CNSs, which enhanced their dispersibility in water. The layer structure of the CNSs remained unchanged after the acid treatment.

液苯介质放电制备洋葱状富勒烯

LIU Wen, YANG Yong-zhen, ZHANG Yan, LIU Xu-guang, WANG Xiao-min, XU Bing-she

2007, 22(01): 84-87.

Abstract(2373)

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Abstract:
Onion-like Fullerenes (OLFs) were synthesized by arc discharge in benzene using graphite electrodes. The effect of experimental parameters on the morphologies and structures of the OLFs was investigated by HRTEM and XRD. Results show that electric current is the main factor and the diameters of the OLFs can be controlled in the range between 10 and 30nm.

空气氧化处理对三维编织炭复合材料性能的影响

WANG Yu-guo, WU Guang-shun

2007, 22(01): 88-91.

Abstract(2420)

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Abstract:
A threedimensionally braided carbon fiber reinforced carbon/epoxy resin (C/Ep) composite was prepared by vacuum impregnation, and the effect of air oxidation of the fibers on the properties of the composite were investigated by SEM, nitrogen adsorption and mechanical testing. Results show that the specific surface area and surface roughness of the oxidized carbon fibers increase while their tensile strength decreases with increasing oxidation temperature or time. The flexural strength, flexural modulus, and shear strength of the C/Ep composites under the optimum treatment at 450℃ for 1h were increased by 149%, 91% and 29% respectively compared with the untreated samples, but the impact strength was decreased by 23%.

金刚石薄膜抗激光破坏研究

HAN Jie-cai, GAO Wei, ZHU Jia-qi

2007, 22(01): 92-96.

Abstract(2062)

PDF(1414)

Abstract:
The outstanding optical and mechanical properties of diamond films are summarized. Laser damage for films irradiated with different wave lengths and pulse width are reviewed and the laser damage mechanism analyzed for different parameters. It is found that graphitization induced instability of the crystal lattice is the main reason for laser induced damage. There are two ways that lead to graphitized damage on the surface of diamond films under long and short laser pulses. For nanosecond or longer laser pulses, graphitization propagates vertically into the bulk of the diamond films. For femtosecond laser pulses, graphitization occurs on the surface of the diamond films layer by layer. Based on the physical properties and preparation technology, practical and promising applications of diamond films are proposed.

2007 Vol. 22, No. 01

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