2007 Vol. 22, No. 02

以不同PAN系炭纤维布制备燃料电池气体扩散层之研究(英文)
Tse-Hao Ko, Yuan-Kai Liao, Ching-Han Liu
2007, 22(02): 97-101.
Abstract(2622) PDF(560)
Abstract:
Gas diffusion layers (GDL) in proton exchange membrane fuel cells were prepared by graphitization of polyacrylonitrile carbon fiber cloths, to enhance their properties, such as, electrical conductivity, which was examined by electrical tests, X-ray diffraction, and elemental analysis. The results indicated that electrical resistivity declined, Lc increased, and d002 decreased with an increase in the heat-treatment temperature. Carbon fiber cloths with a higher heatª²treatment temperature performed better as GDLs in terms of current density and power density.
玻璃炭球的二步活化法 —— 一种高活化收率的途径(英文)
WANG Li-hong, Masahito FUJITA, Masahiro TOYODA, Michio INAGAKI
2007, 22(02): 102-108.
Abstract(3237) PDF(834)
Abstract:
A series of activated carbons was prepared using a two-step activation process. The starting glass-like carbon spheres were heated at 500℃ for 3h (first step activation), and then at a low temperature, below 415℃, for different times (second step activation), in a flow of dry air. Their pore structures were evaluated from N2 gas adsorption/desorption isotherms at 77K by BET, αs-plot and BJH methods. The first step of activation generated a few large pores (mesopores and even macropores), on the surface of the spheres, which formed the entrance for the activating reagent gas (air), to increase micropores at a low temperature in the second step of activation. This two-step activation process was found to be an efficient approach to get a comparatively high surface area and a volume of micropores with a high activation yield.
沥青树脂和炭纤维的复合性能
ZHA Qing-fang, GUO Yan-sheng, ZHANG Yu-zhen, HOU Hui-yu, YANG Xiao-jun
2007, 22(02): 109-114.
Abstract(2519) PDF(787)
Abstract:
A new thermosetting pitch resin consisting of condensed aromatic nuclei cross-linked with methylene bridges was prepared by polymerization of a mixture of an aromatic rich fraction from fluid catalytic cracking oils and 1,4-benzenedimethanol at 120℃ with p-toluenesulfonic acid as catalyst. Carbon fiber/resin (CFR) and carbon fiber paper/resin (CFPR) composites were prepared by the hot-pressing method. No remarkable changes in mechanical properties were found when the composites were heated at 250℃ for 10h and 300℃ for 2h and soaked in strong acids or bases for 1 to 70h at room temperature, suggesting that the composites had good thermal stability and resistance to chemical attack. The CFR and CFPR specimens were converted into C/C composites without fissures or cleavages between the pitch resin carbon and carbon fibers by further heat treatment from 950 to 1000℃ under N2 atmosphere. The length of carbon fiber pulled out from the matrix during fracture was of the order of 10μm as seen in SEM photos, indicating that the pitch resin adhered well to the carbon fibers and the CFR and CFPR composites had good mechanical strength.
含钽炭基复合材料前驱体的制备及表征
LI Xiu-tao, SHI Jing-li, GUO Quan-gui, ZHAI geng-tai, LIU Lang, SONG Jin-ren
2007, 22(02): 115-120.
Abstract(2105) PDF(594)
Abstract:
Tantalum-containing pitch as a carbon precursor was synthesized by an in situ liquid phase reaction between coal tar pitch and tantalum pentachloride. The dispersion, chemical state and transformation of tantalum during carbonization and graphitization were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction measurements. Also, the effects of the amount of tantalum pentachloride and reaction time on the softening point of the pitch were investigated. Results showed that the tantalum particles were dispersed homogeneously in the pitch precursor with sizes in the range of 20-50nm. The tantalum particles mainly existed in the form of δ-Ta2O5 when the reaction temperature was 420℃. By further heat treatment, δ-Ta2O5 was transformed into β-Ta2O5 at 900℃. Β-Ta2O5 and TaC co-existed at 1200℃. At 2800℃, all the tantalum was transformed into TaC.
声电化学法在炭织物表面制备的磷酸钙涂层及其对成骨细胞活性的影响(英文)
HAN Hong-mei, Sergey V.Mikhalovsky, Gary J.Phillips, Andrew W.Lloyd
2007, 22(02): 121-125.
Abstract(2547) PDF(1074)
Abstract:
Calcium phosphate coatings were directly deposited on carbon fabric cloths, using a novel method, sonoelectrochemical deposition, in aqueous electrolytes containing calcium and phosphate ions, at pH ~4.7, and at a relatively low temperature of 50℃, with the aim of investigating the usefulness of the resulting composites for reconstruction of bone defects. The deposits were characterized with the help of infrared spectroscopy and scanning electron microscopy, with energy dispersive X-ray microanalysis. Human osteoblast-like cells (MG63) were used to investigate the cell/biomaterial interaction in vitro. Results showed that the composition and the morphologies of phosphate deposits were dramatically influenced by the application of ultrasound, which appeared to offer a number of potential advantages over the simple electrochemical processes. In vitro MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt) assay confirmed the significant improvement in the cell attachment, and proliferation was because of the phosphate deposits prepared by sonoelectrodeposition rather than the traditional silent one.
铁-硫协同作用对甲苯热解产物的影响
MA Hai-long, JIN Guo-qiang, WANG Ying-yong, GUO Xiang-yun
2007, 22(02): 126-130.
Abstract(2258) PDF(741)
Abstract:
Different carbon products were obtained by the pyrolysis of toluene using ferrocene as catalyst precursor and thiophene as promoter. The effect of catalyst and promoter on the morphologies and microstructure produced were investigated by TEM and XRD. The pyrolysis product consisted of spherical carbon nanoparticles when no catalyst or promoter was used. Some nanoparticles in the product were linked together into chain-like structures. When ferrocene was used alone, Fe-encapsulated carbon nanoparticles were the main product. When ferrocene and thiophene were used together, the product morphologies were related to the thiophene content. The above results suggest that the coexistence of Fe and S has a large synergetic effect on the pyrolysis reaction and the product formation process.
炭/炭复合材料表面氧化硼减摩涂层研究(英文)
HU Zhi-biao, LI He-jun, FU Qian-gang, XUE Hui, SUN Guo-ling
2007, 22(02): 131-134.
Abstract(2928) PDF(1146)
Abstract:
B2O3 lubricating coatings for the SiC coated C/C composites were prepared by a slurry brushing method. The morphologies, components, and structure of the as-prepared coatings were characterized by SEM and XRD. The friction coefficient of the coatings was also tested. The lubricating mechanism of the coating is discussed. Results show that the friction coefficient of the coatings is 0.06-0.08, which is less than that of the carbon/carbon composites (0.15-0.18). The decrease of the friction coefficient of C/C composites after adding a SiC/B2O3 coating is attributed to the formation of a lubricious layer of boric acid from the boron oxide after exposure to the moisture in air.
微孔结构与表面改性对活性炭吸附储氢能力的影响(英文)
SU Wei, ZHOU Ya-ping, WEI Liu-fang, SUN Yan, ZHOU Li
2007, 22(02): 135-140.
Abstract(2675) PDF(933)
Abstract:

The effect of the microstructure of coconut-shell-based activated carbons, and their treatment with chemicals, on hydrogen adsorption capacity was studied. Active carbons from coconut shells using physical activation could be improved for hydrogen adsorption by treatment with HF or NH3•H2O. Treatment with HNO3 had no obvious effect and the treatment with H3PO4 lowered the hydrogen adsorption capacity considerably. All of the effects could be accounted for by changes in the specific surface area, pore size distribution, and surface chemistry of the active carbons. The specific surface area of carbons was the dominant factor for hydrogen adsorption no matter what kind of treatment was performed.

沸石矿模板炭的制备及其纳米孔的形成机理
WANG Ai-ping, KANG Fei-yu, HUANG Zheng-hong, GUO Zhan-cheng
2007, 22(02): 141-147.
Abstract(2322) PDF(737)
Abstract:

Porous carbons were prepared using zeolite ore and artificial type X zeolite as templates, and sucrose as carbon source. Field-emission scanning electron microscopy and nitrogen adsorption analysis were employed to study the morphologies and pore structure of the samples. Results indicate that the BET specific surface area of zeolite ore templated porous carbon (1070m2/g) is lower than that of type X zeolite templated porous carbon (1820m2/g) while the total pore volume (1.39cm3/g) and mesopore volume (0.98cm3/g) of porous carbon obtained using zeolite ore as the template are much larger than that of porous carbon obtained by using type X zeolite as the template, which are 1.02cm3/g and 0.39cm3/g respectively. The nanopores of natural zeolite templated porous carbon are composed of three kinds of pores: one is formed by removal of ore which means “templated pores”, the second is inherited from template pores which we call “hereditary pores” and the third is formed during carbonization.

基于SQL Server的C/C复合材料实验数据库系统平台的设计开发
TANG Hui, QI Le-hua, LI He-jun
2007, 22(02): 148-152.
Abstract(2820) PDF(853)
Abstract:
For resolving the problems of storage and reasonable application of a great deal of experimental data in the production of C/C composites by CVI, an experimental database platform for C/C composites was developed based on a structured query language server software as the basic database and VC+ + as the development platform. The connection between the platform and database was constructed with the ActiveX Data Objects, a data interface technique developed by Microsoft. The experimental data were divided into five classes, including process methods, process analysis, property analysis, microstucture analysis, and anti-oxidation coating and its efficacy. The CVI simulation and optimization were performed by integrating this platform with the Matlab-engine technique, results of which can be used to shorten the C/C composite production time, to improve the efficiency, and to lower the cost.
炭气凝胶/活性炭复合电极在有机电解液体系双电层电容器中的阻抗(英文)
LIU Xi-miao, ZHANG Rui, ZHAN Liang, LONG Dong-hui, QIAO Wen-ming, YANG Jun-he, LING Li-cheng
2007, 22(02): 153-158.
Abstract(2565) PDF(527)
Abstract:
Abstract:Carbon aerogel (CAG), carbon black (CB), and graphite (G) were added to a high surface area activated carbon (HSAC), prepared by KOH activation, to form composites for use as electrodes of electrochemical capacitors (ECs). The performance of the ECs using these electrodes in (C2H5)4NBF4/propylene carbonate electrolyte were analyzed and compared by an electrochemical impedance spectrum (EIS). An equivalent circuit model with mixed kinetic and charge transfer control was assumed and a Marquardt fit procedure was applied to the EIS data, from which model parameters, such as, series solution resistance, Rs, polarization resistance, Rp, Nernst diffusion layer thickness, δ, and average value of the diffusion coefficients of electrolyte ions, D, were extracted and compared for CAG-, CB-, and G-based composites. It was found that the ECs using CAG had the highest D values and a comparable Rp value with CB. The CAG-based composite had the lowest resistance and highest capacitance at the same frequencies among the three types of composites investigated.
Lyocell/多壁碳纳米管复合纤维的制备及性能
LU Jiang, JIAN Yi-hui, ZHANG Hui-hui, SHAO Hui-li, HU Xue-chao
2007, 22(02): 159-164.
Abstract(4133) PDF(957)
Abstract:
Lyocell/multiwalled carbon nanotube (MWCNT) composite fibers were prepared by the dry-wet spinning of an aqueous suspension containing MWCNTs, N-methylmorpholine N-oxide and the cellulose. The structure and properties of the composite fibers were investigated by WAXD, SEM, TEM and tensile testing. WAXD patterns showed the composite fibers had the cellulose II crystal structure and retained the characteristic peak of carbon nanotubes. The two dimension X-ray diffraction patterns showed that the composite fibers with mass fraction 5% MWCNTs had a mosaic angle of ±15.2°, which means that the MWCNTs were preferentially aligned along the axis of the fibers. The SEM showed that the MWCNTs were dispersed uniformly in the matrix. The addition of an appropriate amount of MWCNTs could improve the mechanical properties of the composite fibers. The initial modulus and tenacity of the composite fibers containing a mass fraction of 1% MWCNTs were increased by 4.49% and 15.7%, respectively, compared to the Lyocell fibers.
基于炭纤维水泥基材料电阻率变化的水化进程监测
HAN Bao-guo, GUAN Xin-chun, OU Jin-ping
2007, 22(02): 165-170.
Abstract(2211) PDF(579)
Abstract:
The electrical resistance of cement paste with and without carbon fibers during hydration was measured and the relationship between hydration and compressive strength and electrical resistance was investigated. The effect of adding an early-strengthening agent or heating was also studied. Results show that the electrical resistance of the cement paste fluctuates sharply during measurement because of strong polarization. The fluctuation of electrical resistance of the carbon fiber reinforced cement paste (CFRCP) disappears when more than mass fraction 0.30% of carbon fibers is added, and the electrical resistance shows a linear relation to the extent of hydration when the carbon fiber mass fraction is 0.35%. The same results are observed for CFRCP treated by the early-strengthening agent or heat curing. Therefore, it is feasible to monitoring the hydration of cement-based materials by testing its electrical resistance.
预氧化聚碳硅烷纤维热分解动力学及其机理
ZHENG Chun-man, LI Xiao-dong, YU Yu-xi, WANG Hao, FENG Chun-xiang
2007, 22(02): 171-176.
Abstract(2267) PDF(818)
Abstract:
Abstract: The thermal decomposition of pre-oxidized polycarbosilane (PCS) fibers was carried out in a thermogravimetric analyzer under non-isothermal condition. The Coats-Redfern equation was used to estimate the apparent activation energy in thermal decomposition and the mechanism of thermal decomposition was studied by IR, XRD and SEM. It was found that the thermal decomposition of pre-oxidized PCS fibers was a first order reaction and the apparent activation energy was estimated to be 19.826kJ/mol. The thermal decomposition process was a dehydrogenation and dehydrocarbonation condensation with the evaporation of low molecular components at low temperature. With increasing temperature the fibers were converted into an inorganic structure by decomposition of the side chains of the polymer. When the temperature was further increased, the crystallite size of SiC increased and the fibers became completely inorganic; above 1250℃. The mechanical properties of the SiC fibers became lower with the rapidly increasing crystallite size of the β-SiC.
在氧化铁表面沉积热解炭及其气化与还原
WU Wen-jun, ZHU Yong-ping, ZHANG Wei-gang
2007, 22(02): 177-182.
Abstract(2485) PDF(542)
Abstract:
Thermodynamic analysis and chemical vapor deposition (CVD) of pyrolytic carbon on the surface of needle-like goethite (FeOOH) in a flow reactor were carried out. It was found that CVD of carbon from propylene occurred on the surface below 600℃. With the deposition of pyrocarbon, the surface area of the FeOOH decreased rapidly and mass loss occurred resulting from dehydration. With increasing CVD temperature, Fe2O3 was reduced gradually to Fe3O4 and FeO and finally Fe3C as the CVD temperature exceeded 800℃. Carbon deposited on the surface of iron oxide below 500℃ limited the morphological change of nano FeOOH from large aspect ratio particles to spherical particles. At higher temperatures (600-700℃), carbon deposition led to the formation of dumbbell shaped iron oxide. The two forms of iron oxide can be reduced by carbon monoxide or hydrogen into pure iron or carbon coated iron with high aspect ratios or a dumbbell shape.
金刚石膜的氮掺杂行为
LI Ming-ji, LU Xian-yi, SUN Bao-ru, LI Chun-yan, LI Bo, JIN Zeng-sun
2007, 22(02): 183-187.
Abstract(1925) PDF(440)
Abstract:
Nitrogendoped diamond films were synthesized by electron assisted chemical vapor deposition. The quality and chemical state of nitrogen in the diamond films were characterized by SEM, Raman, XPS, and EPR. Results showed that the morphologies of the diamond films changed from integrated facets to the “cauliflower-like” diamond (100) faces, the amorphous carbon content increased and its quality dropped with increasing nitrogen flow rate. The chemical state of nitrogen in the diamond films was of the form Ns0, [N-V]0 and [N-V]-1. The amounts of [N-V]0 and [N-V]-1 were higher when the nitrogen flow rate was lower, and the mass fraction of Ns0 varied from 1.50×10-5 to 4.83×10-4.
三维针刺C/SiC摩擦材料的拉伸性能
FAN Shang-wu, XU Yong-dong, ZHANG Li-tong, CHENG Lai-fei, LOU Jian-jun
2007, 22(02): 188-192.
Abstract(1915) PDF(835)
Abstract:
Cost effective and high performance 3D needled carbon/silicon carbide friction materials were prepared by a combination of chemical vapor infiltration and reactive melt infiltration. The microstructures and tensile properties of the composites were studied. Results indicated that the composites consisted of carbon, silicon and silicon carbide. The density and porosity of the composites were about 2.1g·cm-3 and 4.4% respectively, and the tensile strength and Young’s modulus were about 114-154MPa and 40-63GPa respectively. The composites exhibited excellent pseudo-plastic behavior similar to that of metal. The main toughening mechanism of the as-prepared composites was fiber pull-out, interfacial debonding, deflection of cracks, bridging of fibers and bifurcation of cracks.