新型炭材料

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

2005, 20(02): 97-102.

Abstract(2711)

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Abstract:
The morphology and microstructure of a 3D carbon/carbon composite, and the corresponding composites doped with refractory metal carbides, were studied by SEM and TEM after ablation tests at various conditions. Results showed that in the case of composites doped with refractory metal carbides, the carbon fibers in the Z-direction were ablated faster than the matrix carbon. The bigger the difference of ablation rate between the carbon fibers and the matrix carbon, the greater the ablation rate of the bulk material. In contrast, in the carbon/carbon composite, the matrix carbon at the interface region was ablated faster than the carbon fibers. Micro-crystalline growth of carbon fibers and formation of columnar shaped carbon in the matrix carbon were commonly observed. Ablation conditions had a great influence on the morphology and the ablation mechanism.

H2O2原位净化定向碳纳米管阵列的研究

WANG Ye, BAI Xiao-dong, LIANG Ji

2005, 20(02): 103-107.

Abstract(2599)

PDF(1574)

Abstract:
A non-template chemical vapor deposition (CVD) method was adopted to prepare highly directional and self-standing aligned carbon nanotube (ACNT) arrays on a quartz substrate on a large-scale and H2O2 was used to in-situ oxidize impurities in the arrays. It is found that the in-situ purification of ACNT arrays by H2O2 is an efficient way to purify ACNT arrays without damaging their alignment and the ACNT arrays obtained have a different thickness. In most cases the tips were open with a smaller amount of amorphous carbon, disfigured CNTs and other impurities. Such arrays have potential applications in field emission. The results of Raman spectroscopy and TGA show that the crystallization and thermal stability of ACNT arrays increase after the purification.

熔融纺丝方法制备纳米碳管/聚丙烯复合纤维及其拉伸性能(英)

LI Zhong, YING Zhe, LIU Min, CHENG Hui-ming

2005, 20(02): 108-114.

Abstract(2943)

PDF(811)

Abstract:
Well-aligned, long fibers composed of multi-walled carbon nanotubes (MWNTs) and polypropylene (PP) were fabricated by a conventional melt spinning technique. Scanning electron microscope (SEM) observations of the morphology revealed that both the alignment and dispersion of MWNTs in the matrix were improved. Mechanical properties of the composite fibers were studied by tensile testing and Weibull distribution, and it was found that their tensile strength was increased with addition of the carbon nanotubes. The maximum tensile strength of 61MPa was achieved at 3w/% MWNT addition, 120% more than that of the pure PP fibers. Moreover, a unique tensile rupture characteristic was found by SEM observations, which explained the critical phenomenon that the MWNT addition affects the tensile property of the MWNT composite fibers.

载体炭对CuO/AC(F)催化-吸附剂干法催化氧化苯酚的影响

ZHAO Jiang-hong, LIU Zhen-yu

2005, 20(02): 115-121.

Abstract(2577)

PDF(1442)

Abstract:
Four activated carbons (fibers) were chosen to prepare dual functional materials, CuO/AC(F) catalyst-sorbents. They were tested in order to investigate the effect of carbon supports on CuO/AC(F) catalyst-sorbents used for catalytic dry oxidation of phenol. A TG-MS instrument was used to study the phenol oxidation activity of CuO/AC(F) catalyst-sorbents and the ignition activities of the catalyst-sorbents themselves. The properties of the carbon supports and CuO/AC(F) catalyst-sorbents were characterized by BET and XRD. Results indicate that the ash from the carbon supports affects, and mesopores promote, the phenol oxidation activities of CuO/AC(F) catalyst-sorbents. Surface oxygen functional groups on carbon supports have no significant effect on the phenol oxidation activities of the-sorbents, but they and impurities from the carbon supports promote the ignition activities of CuO/AC(F) catalyst-sorbents themselves. Phenol oxidation and catalyst-sorbent ignition may proceed bt different reaction mechanisms.

超临界水和水蒸气活化制备酚醛树脂基活性炭的对比研究

CAI Qiong, HUANG Zheng-hong, KANG Fei-yu

2005, 20(02): 122-128.

Abstract(3287)

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Abstract:
A new activation method, supercritical water activation (650℃, 32Pa), and a traditional method, steam activation (650℃), were used to prepare phenolic resin based activated carbons. Based on pore structure characterization of the samples by nitrogen adsorption and weight loss behavior of the starting materials by TG/DSC analysis, the effects of the two different activation methods and the degree of carbonization of the starting materials on the evolution of the pore structure of phenolic resin-based activated carbons were obtained. Results show that: (1) supercritical water activation benefits the development of mesoporosity, while steam activation benefits the development of microporosity; (2) activated carbons with high specific surface area and mesoporosity were obtained at a low degree of burn-off from phenolic resin-based carbons carbonized to a low degree.

不同原料合成COPNA树脂及其黏结性

HOU Hui-yu, ZHA Qing-fang, GUO Yan-sheng, YANG Xiao-jun, ZHANG Yu-zhen

2005, 20(02): 129-133.

Abstract(2344)

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Abstract:
Four different condensed polynuclear aromatic (COPNA) resins were obtained by reacting different heavy residue oils with 1,4-benzenedimethanol and p-toluenesulfonic acid. Their adhesive related properties including softening-point, carbon residue, β resin content, were tested. Four different composites using them as binders were made by molding different resins with carbon fibers and their mechanical properties were tested. Results showed that the mechanical properties of the composites from COPNA resins from Daqing slurry are better than those from conventional bakelite and epoxy resin. This is ascribed to their good adhesion to the carbon fibers.

制备条件对炭泡沫结构的影响(英)

CAO Min, ZHANG Shu, WANG Yong-gang

2005, 20(02): 134-138.

Abstract(2328)

PDF(1882)

Abstract:
A carbon foam was prepared from petroleum mesophase pitch in a high pressure/high temperature reactor by self-bubbling of volatile gas and infiltration of nitrogen at high pressure. The carbon foam was characterized by SEM and light microscopy. It was found that temperature and pressure are important factors in determining the carbon foam structure. Higher temperature tends to enlarge pore size and increase the percentage of open porosity. Increasing pressure decreases pore apertures size and improves density. A highly regular arrangement of carbon layers along the filament can be obtained at high temperature.

CVI法制备2D C/C复合材料

TANG Su-fang, ZHOU Xing-ming, DENG Jing-yi, DU Hai-feng, LIU Wen-chuan

2005, 20(02): 139-143.

Abstract(2702)

PDF(1487)

Abstract:
2D C/C composites of 24mm thickness were prepared by chemical vapor infiltration (CVI) for 25.5h using liquefied petroleum gas as carbon source in a cold furnace, where 2D preforms were heated by passing electrical current through them. The rapid densification mechanism of the process was investigated, and microstructures of the materials were observed. Results show that CVI can be used to prepare C/C composites with uniform structure and good mechanical properties in a shorter time. The mechanism of rapid densification by CVI includes magnetic attraction of radicals, electric deposition of radicals, and dehydrogenation and aggregation of radicals.

聚丙烯腈纤维在预氧化过程中的结构和热性能转变

ZHANG Li-zhen, LU Chun-xiang, LU Yong-gen, WU Gang-ping, HE Fu

2005, 20(02): 144-150.

Abstract(2285)

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Abstract:
Polyacrylonitrile fibers were pre-oxidized in air at temperatures from 180℃ to 265℃. The morphological rearrangement, chemical reactions and the variation of thermal properties during the continuous thermal oxidative stabilization were characterized by X-ray diffraction, FT-IR, DSC and TG. Results showed that: (1) When the pre-oxidative temperature was below 200℃, the cyclization reaction was slow. When the temperature increased from 200℃ to 230℃, the cyclization index increased rapidly and the reaction was drastic. The reaction rate reduced after the pre-oxidative temperature reached above 230℃. (2) The pre-oxidation reactions were first initiated in an amorphous region, thereafter the reactions propagated to the crystalline regime at high temperatures where reactions were drastic. (3) When the pre-oxidative temperature was below 210℃, the crystal size increased, corresponding to stress crystallization. The crystallite size decreased rapidly after the pre-oxidative temperature reached above 210℃.

C/C复合材料特性对其摩擦磨损性能的影响

LI Xin-chun, YI Mao-zhong, FENG Yi-lei, GE Yi-cheng, HUANG Qi-zhong

2005, 20(02): 151-156.

Abstract(3316)

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Abstract:
The sliding friction and wear behaviors of C/C composites to be used in the seal ring of the main axis of turbine engines for airplane were tested on a MM-2000 ringblock frictional tester. The effect of preparation conditions, graphitization treatment in the final step, density, and carbon fiber direction in the composites on the behavior was investigated. It is found that after CVI, resin impregnation, densification and graphitization, the C/C composites have good tribology properties. When the composites are graphitized in the final step, their densities are higher and tribology properties are better than those of ungraphitized samples. When the load is moderate, the friction coefficient of perpendicular samples is higher than that for parallel ones, but the volume loss of perpendicular samples is lower than that for parallel ones. The C/C composite rings are superior to those made of high strength graphite for this application.

石墨化温度对炭纤维微观结构及其力学性能的影响

WANG Hao-jing, WANG Hong-fei, LI Dong-feng, ZHU Xing-ming, HE Fu, WANG Xin-kui

2005, 20(02): 157-163.

Abstract(2585)

PDF(2580)

Abstract:
The effect of graphitization temperature on the microstructure, elemental composition, surface character and mechanical properties of carbon fibers was studied by means of SEM, XRD, Raman spectroscopy, elemental analysis and mechanical testing. It was found that with an increase of heat treatment temperature ranging from 1800 to 3000℃, the percent carbon increases from 92.62% to 99.99%, the interlayer spacing d002 decreases, both d100 and the d110 increase, La and Lc increase, tensile strength decreases, and Young’s modulus increases.

超声辅助湿法合成纳米HA及MWNT/HA复合材料

WEI Qiang, YANG Xiao-ping, CHEN Guo-qiang, TANG Jin-tian, DENG Xu-liang

2005, 20(02): 164-170.

Abstract(3210)

PDF(1508)

Abstract:
Hydroxyapatite (HA) or MWNT/HA was synthesized by reacting Ca(NO3)2·4H2O with (NH4)2HPO4 with the help of ultrasonic agitation in the absence or presence of MWNTs, and the resulting HA and MWNT/HA were characterized by IR, XRD and TEM. Results indicated that HA samples were almost completely composed of nano-sized spindle-like HA crystals, which were all of the same crystal phase and high crystallinity without agglomeration. Under optimized reaction parameters for HA crystals, the MWNTs were well dispersed in the HA matrix and some HA even deposited onto the MWNT surfaces and coated them, indicating a good compatibility between HA and MWNTs.

碳源对CVI炭/炭复合材料致密和结构的影响

XIE Zhi-yong, HUANG Qi-zhong, SU Zhe-an, ZHANG Fu-qin, GAO Ying, HUANG Bo-yun

2005, 20(02): 171-177.

Abstract(2719)

PDF(1433)

Abstract:
Chemical vapor infiltration (CVI) of carbon felts to fabricate C/C composites was carried out by implanting a special electrically conductive layer in the carbon felts, which resulted in rapid densification by a coupling effect of temperature gradient, reaction intermediate gradient, and magnetic field. Liquefied petroleum gas (LPG) and C3H6 were employed as carbon sources. The deposition temperatures were in the range of 800-1000℃, and the deposition pressure was in the range of 0.1-15.0kPa. The textures of the pyrolytic carbons were observed by polarized light microscopy, and the crystallite size of these C/C composites was analyzed by XRD. Results show that infiltration of the porous C/C performs, 260mm×60mm×20mm, for 20h leads to C/C composites with density of more than 1.7g/cm3 from LPG, and of more than 1.6g/cm3 from C3H6. The deposition rate for LPG under optimized conditions was more rapid than for C3H6. It is shown that LPG mixed with hydrocarbon gas, whose activation energy is different, can cooperate with other physical fields to improve the deposition rate and texture of the pyrolytic carbons.

脱硫脱硝活性炭的研究

LI Tong-chuan, NIU He-san

2005, 20(02): 178-182.

Abstract(2827)

PDF(2593)

Abstract:
Activated carbons were prepared from various coals and employed to remove NOx and SOx from a simulated flue gas. Results show that the best activated carbon tested, in terms of de-NOx and de-SOx performance, is produced from sub-bituminous coal. The addition of coking coal can decrease the abrasive wear of the activated carbon in a fluidized bed, and the optimum amount of coking coal is determined to be 25w/%. A post-oxidation process can be used to greatly improve the de-SOx and de-NOx performance of the resultant activated carbons.

活性炭孔结构调节：理论、方法与实践

XIE Qiang, ZHANG Xiang-lan, LI Lan-ting, JIN Lei

2005, 20(02): 183-190.

Abstract(2223)

PDF(2819)

Abstract:

2005 Vol. 20, No. 02

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