新型炭材料

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

2006, 21(01): 1-8.

Abstract(2379)

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Abstract:
Two types of bamboo, i.e. Phyllostachys heterocycla, Bambusa arundinacea, were selected as the raw materials to produce charcoal and SiC ceramics. First, biological carbon preforms were derived from bamboo by pyrolysis under N2 atmosphere, and then used as templates for molten silicon infiltration at 1450℃ in an argon atmosphere to form SiC ceramics. The pyrolysis process was studied by TGA, SEM, energy dispersive analysis of Xrays and XRD was used to characterize the microstructure, phases and physicochemical structure changes during the wood toceramic conversion. The compressive mechanical behavior of the bambooderived SiC materials was measured by a universal testing machine. Results show that the carbon preforms and the final SiC ceramics both inherit the anisotropic microstructure of bamboo. The SiC ceramics prepared by this technique are multiphase solids composed of SiC, freesilicon and C. The SiC ceramic materials produced from these two bamboo species show differences in fracture, phasecomposition and compressive strength.

掺杂难熔金属碳化物对炭/炭复合材料烧蚀机理的影响

WANG Jun-shan, LI Zhong-ping, AO Ming, XU Zheng-hui, LIU Lang, HU Zi-jun, PENG Wei-zhou

2006, 21(01): 9-13.

Abstract(2488)

PDF(1733)

Abstract:
The microstructures of carbon/carbon composites (C/C) and refractory metal carbidedoped carbon/carbon composites (C/C+MC) were compared to elucidate their ablation mechanism in an arc jet heater. It was found that refractory metal carbides (MC) entered the crystallites of the composites to a depth of several microns from the ablated surface and obviously influenced the texture around them. The existence of MC aggravated not only the weight loss caused by mechanical peeling off but also the surface roughness of the samples. As a result, the ablation speed of C/C+MC was higher than that of C/C although MC decreased the total quantity of sublimed carbon.

炭化温度对CO2活化PAN基活性炭纤维微结构的影响(英）

XU Bin, WU Feng, CAO Gao-ping, YANG Yu-sheng

2006, 21(01): 14-18.

Abstract(3275)

PDF(2079)

Abstract:
A series of activated carbon fibers (ACFs) was prepared by carbonizing pre-oxidized PAN fibers at temperatures ranging from 400 to 900℃ followed by CO2 activation and the effect of carbonization temperature on the porous structure of polyarcylonitrile (PAN)-based ACFs characterized by nitrogen adsorption was investigated. It is found that the porous structure of PAN-ACF depends strongly on the carbonization temperature, and a moderate carbonization temperature (600℃) is favorable to obtain ACFs with higher specific surface area, larger pore volume and larger pore size.

以煤为碳源直流电弧法制备单壁纳米碳管绳

ZHAO Zong-bin, QIU Jie-shan, WANG Tong-hua, LI Yong-feng, Zhou Ying

2006, 21(01): 19-23.

Abstract(2651)

PDF(1536)

Abstract:
Single-walled carbon nanotube ropes (SWCNTRs) were successfully fabricated on a large scale from coal-based composite carbon electrodes using the arc discharge method. The SWCNTRs obtained were characterized by TEM and Raman spectroscopy. Results show that the Taixi coal used in the present work is a suitable carbon source for the synthesis of high purity SWCNTRs in the presence of catalysts such as La and Ni. The diameter distribution of the obtained SWCNTRs varies from 1.80 to 2.01nm and the bimetal La/Ni catalyst plays a synergetic role in the catalytic synthesis of SWCNTRs.

掺杂磁性铁粒子膨胀石墨的制备及其对毫米波的干扰作用

REN Hui, KANG Fei-yu, JIAO Qing-jie, CUI Qing-zhong

2006, 21(01): 24-29.

Abstract(2222)

PDF(1893)

Abstract:
Magnetic iron particle-doped expanded graphite was prepared by dipping, stirring and standing an expandable graphite for 5-8h in ferrocene then expanding at 500℃. The surface morphology and composition of the expanded graphite were characterized by SEM and elemental analysis while the magnetization curves, magnetic susceptibility and the attenuation properties for an 8mm wavelength electromagnetic signal were characterized by a vibration magnetometer. Results showed that ferric oxide was deposited on the surface of the expanded graphite. The average magnetic intensity of the expanded graphite prepared is higher than 8emu/g under a magnetic field intensity of 0-7.958×105A/m. The largest attenuation is over-10dB and its mass extinction coefficient is over 1.0g/m2 in the wave length of military radar, which is better than a current millimeter wave radar shielding material.

乙烯催化裂解法选择性合成纳米炭纤维（英）

SONG Yan, QIAO Wen-ming, Seong-Ho Yoon, Isao Mochida

2006, 21(01): 30-35.

Abstract(2475)

PDF(1538)

Abstract:
Carbon nanofibers (CNFs) with various structures were selectively synthesized through the catalytic pyrolysis of ethylene using nonsupported and SiO2-supported metals (such as iron, nickel, iron/nickel alloy). Tubular, solid herringbone and hollow herringbone structures were obtained by using SiO2-supported Fe, Ni and Fe-Ni catalyst, respectively. Uniform CNFs with small diameter and high yield were synthesized using SiO2-supported catalyst because of the strong metal-support interaction, which results in high reactive activity at relatively a low temperature. The different structures of the resultant CNFs were ascribed to the dispersion of the metal catalyst and the different growth mechanisms. Normally Fe catalyst displays poor activity for the synthesis of CNFs by CVD of ethylene even at high temperature up to 650℃. However, tubular CNFs were prepared at a very low temperature of 500℃ by using SiO2-supported iron catalyst in our experiments.

短切炭纤维增强沥青基C/C复合材料的力学性能

GUO Ling-jun, LI He-jun, XUE Hui, LI Ke-zhi, FU Ye-wei

2006, 21(01): 36-42.

Abstract(3297)

PDF(1558)

Abstract:
Short carbon fiber reinforced pitch-based carbon/carbon composites (SCFRC) with high density and low cost were fabricated by mold pressing followed by semi-carbonization. The effect of the volume fraction of short carbon fibers on density and mechanical properties of the SCFRC was studied. Their microstructures and fracture morphologies were observed using an optical microscope and SEM, and the reinforcing mechanism of the short carbon fibers was elucidated. Results show that mechanical properties increase linearly with an increase of short carbon fiber volume fraction from 0% to 11.8%, and the strengthening mechanisms involved are based mainly on crack deflection, fiber bridging, fiber debonding and pull-out.

催化化学气相渗透法制备C/C复合材料

ZHOU Zhen-zhong, LI Tie-hu, AI Yan-ling, SONG Fa-ju, LIN Qi-lang

2006, 21(01): 43-47.

Abstract(2415)

PDF(1571)

Abstract:
Catalytic isothermal chemical vapor infiltration fabrication of carbon/carbon(C/C) composites was investigated by polarized light microscopy, SEM and XRD in order to speed up the deposition efficiency and to enhance the oxidation-resistance of the matrix carbon. The influence of Ni/ZSM-5 supported catalysts on the deposition rate of matrix carbon is investigated by comparing pure C/C composites and C/C composites added with catalytic Ni/ZSM-5 powder. Results show that the pyrocarbon growth rate is faster in carbon fiber cloth substrates doped with supported catalysts than in the undoped one. Both the microstructure of the pyrolytic carbon and its oxidation-resistance have a close correlation with the amount of Ni/ZSM-5.

超级电容器用沥青焦基活性炭的制备及其电化学性能

LIU Xi-miao, ZHAN Liang, TENG Na, YANG Deng-lian, ZENG Xiao-chun ZHANG Rui, LING Li-cheng

2006, 21(01): 48-53.

Abstract(2667)

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Abstract:
A series of petroleum coke-based superactivated carbons (SACs) was prepared by KOH activation. Electrochemical performance of the SACs and a porous carbon called YP15 (Kuraray Chemical Co., Japan) as electrodes of supercapacitors in aqueous and nonaqueous electrolytes were characterized and compared by chronopotentiograms, cyclic voltammetry and AC impedance spectrum analysis. It was found that the specific capacitances of SACs increased with surface area and the highest values in the electrolytes of KOH, H2SO4,(C2H5)4NBF4/propylene carbonate(PC), and (C2H5)4NBF4/acetonitrile, were 257F/g, 228F/g, 140F/g and 142F/g respectively, all greater than that of YP15. The ESR volume resistivities of the SACs were lower than that of YP15 in 1mol/L H2SO4, higher than that of YP15 in 1mol/L (C2H5)4NBF4/PC, and close to that of YP15 in 3mol/L KOH. The ESR volume resistivity of the SACs in 1mol/L (C2H5)4NBF4/acetonitrile, which was prepared at 800℃ for 3h using a KOH to petroleum coke ratio of 4∶1, was lower than that of YP15.

成纤过程中PAN纤维聚集态结构形成的研究

HAN Shu-peng, XU Liang-hua, CAO Wei-yu, YAO Hong, BAI Li-fang

2006, 21(01): 54-58.

Abstract(2153)

PDF(1482)

Abstract:
Changes to the crystalline state and orientation texture of PAN fibers during coagulation, wet-drawing, hot-drawing and the drying densification stage were studied by XRD, SEM and acoustic velocity measurements, from which the evolution of PAN aggregate state in the fiber formation process was derived. Results showed that the crystalline state of PAN, which could be described as two-phase with distinct pseudocrystalline (ordered) and amorphous (disordered) phases, was largely produced during the coagulation stage, and the orientation texture was mainly controlled by wet-drawing and hot-drawing. The former plays an important role in the crystalline perfection, while the effect of the latter is to improve the degree of orientation. The drying densification process favors the growth of pseudocrystalline regions while consolidating the orientation texture.

不同厚度四面体非晶碳薄膜的拉曼表征和内应力

ZHU Jia-qi, HAN Jie-cai, GAO Wei, MENG Song-he

2006, 21(01): 59-63.

Abstract(2304)

PDF(1519)

Abstract:
To investigate the effects of film thickness on Raman characteristics and intrinsic stress of tetrahedral amorphous carbon (ta-C) and to ascertain the correlations between stress and Raman spectra, ta-C films with different film thickness were deposited on a polished P-type (100) monocrystalline silicon substrate by a filtered cathodic vacuum arc technology. The film thickness was measured by a surface profiler and AFM, and stress was calculated according to the curvature of samples examined by the surface profiler while the microstructure of the films was characterized by Raman spectra. It is found that the stress drops continuously and then levels off with the increase of film thickness. When the film thickness exceeds 30nm, the compressive stress is less than 5GPa. The intensity of the first and second order peak of the monocrystalline silicon substrate in the Raman spectra gradually decreases with the increase of thickness. For film thicknesses from 50nm to 80nm, the full width at half maximum of the peak is a minimum, the intensity of the peak is a maximum, and the clearest Raman signals can be acquired. Additionally, the position of the broad peak gradually shifts to a lower wave number with the increase of thickness and the decease of intrinsic stress.

生物活性炭纤维的制备及其水处理

ZHOU Juan-juan, HU Zhong-hua, LIU Ya-fei, YIN Yan-e, TANG Wen-wei

2006, 21(01): 64-69.

Abstract(2419)

PDF(1505)

Abstract:
A water treatment technique using biological activated carbon fiber (BACF) instead of granular activated carbon (GAC) was studied. First, the possibility of microbe immobilization on ACF was confirmed by means of raw water flowing through the ACF column. The microbe growth on ACF was investigated by SEM. Then, sludge liquor (SL) incubation and microbe liquor (ML) incubation were used to plant microbes on BACF to form SL-BACF and ML-BACF. The resultant BACFs were subjected to standard water treatment testing for raw water containing small amounts of pollutants. The ability of the BACF process for organic pollutant removal was better than that of BAC. The remaining chemical oxygen demand in the outflow meets the Chinese sanitary standard for drinking water quality. Comparing the two BACFs, it was found that ML-BACF was superior to SL-BACF in terms of treatment efficiency and flow capacity, although the amount of microbes immobilized on the former was less than that of the latter.

Ho/Ni作为催化剂合成单壁碳纳米管

YAO Ming-guang, LIU Bing-bing, ZOU Yong-gang, LI Dong-mei, AI Xiao-Lei, WANG Lin, YU Shi-dan, ZOU Guang-tian, B Sundqvist

2006, 21(01): 70-74.

Abstract(2823)

PDF(1670)

Abstract:
SWCNTs were synthesized with high yield by DC arc discharge using Ho/Ni as catalysts. The morphologies, diameter distribution and the content of SWCNTs in the products were characterized by SEM, Raman scattering and TGA. Results indicate that SWCNTs can be efficiently synthesized with Ho/Ni as catalysts. The volume content of SWCNTs in a "web-like" form is as high as 80% in the product. Furthermore, the diameter distribution of SWCNTs, estimated by analyzing the resonance Raman scattering using excitation wavelengths of 632 and 488nm, varies from 1.35 to 1.69nm with a dominant diameter of 1.5nm, which is different from that of the SWCNTs synthesized with Ce/Ni as catalyst, proving that the diameter distribution of SWCNTs is dependent on the properties of the metal catalysts.

炭纤维的环氧树脂浸润特性

LI Min, ZHANG Zuo-guang, SUN Zhi-jie, LUO Hui-zhen

2006, 21(01): 75-80.

Abstract(2721)

PDF(2361)

Abstract:
In a composite system, the adhesion at the interface between fiber and matrix plays an important role in improving the resulting mechanical behavior. However, interfacial adhesion cannot be achieved without intimate contact. Impregnation flows in T300 and T700 carbon fiber beds were tested when penetrated by a 618 epoxy resin and a AG80 epoxy resin, in both longitudinal and transverse directions. The effects of temperature and fiber volume fraction on the impregnation performance were investigated. Results show that capillary impregnation in the transverse direction is much lower than impregnation in the longitudinal direction. Different trends were found in the analysis of the effect of fiber volume fraction on capillary impregnation in these two directions. With increasing fiber volume fraction, the wicking height increases in the longitudinal impregnation, however, it decreases in the transverse impregnation.

C/C复合材料飞机刹车盘的结构与性能

SU Jun-ming, YANG Jun, XIAO Zhi-chao, ZHOU Shao-jian, PENG Zhi-gang, XIN Jian-guo, LI Rui, HAN Mei, ZHAO Sheng-li, GU Li-min

2006, 21(01): 81-89.

Abstract(2793)

PDF(1891)

Abstract:
Mechanical, physical, thermal, frictional and wear properties of nine carbon/carbon composite materials as aircraft brake discs made by the Chaoma composite material company, Dunlop, Carbon Industry company, B.F.Goodrich, ALS and South-middle University were characterized and compared. Correlation of raw materials and processing parameters by which they were made with their performance was also investigated. Results indicated that an optimum structure of the carbon fiber preform, heat treat temperature, and controlled pyrolysis to form a carbon matrix with a rough laminar microstructure are the key factors to obtain carbon brake disc materials with excellent properties. Homemade carbon brake discs of high quality for large civil aircraft, such as the Boeing 757-200, could be regarded as a breakthrough in the carbon/carbon materials field in China.

高附加值石油焦新材料

ZHENG Yan-jun, CUI Li-shan, CUI Xiao-long, XU Chun-ming

2006, 21(01): 90-96.

Abstract(3073)

PDF(2922)

Abstract:
Petroleum coke can be used as a cheap and readily available carbon source in many engineering applications. With the rapid progress of materials science, petroleum coke shows unique value in producing advanced materials, including high surface area activated carbon, nanometer sized carbide, advanced composite materials, electrorheological fluids, and electrodes for lithium ion batteries. These techniques greatly increase the value added to petroleum coke and have the potential for producing a large economic benefit.

2006 Vol. 21, No. 01

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