2006 Vol. 21, No. 02

膨胀石墨对各种油类的吸附动力学
Michio INAGAKI, Tomoya NAGATA, Taisuke SUWA, Masahiro TOYODA
2006, 21(02): 97-102.
Abstract(2208) PDF(1411)
Abstract:
Sorption kinetics of various oils with different viscosities from 0.001 to 0.850Pa•s into exfoliated graphite column was characterized by measuring sorptivity (effective sorption coefficient) KS and saturated amount of sorption msat. A strong dependence of sorptivity KS on viscosity of oils was observed. Saturated amount of sorption msat into the column was almost a constant of 50kg/kg, which was a little bit smaller than that measured by direct soaking of a lump of exfoliated graphite in oils, due to the presence of a gradient of sorbed oils along the height of exfoliated graphite column.
烧蚀过程中C/C复合材料的结构演变
WANG Jun-shan, Zhong-ping, AO Ming, XU Zheng-hui, LIU Lang, HU Zi-jun, PENG Wei-zhou
2006, 21(02): 103-108.
Abstract(2654) PDF(1547)
Abstract:
Textural changes of a 3D carbon/carbon composite after ablation in an arc jet heater were examined under SEM and TEM. It was shown that obvious enlargement of graphite crystallites was generally observed for both carbon fibers and matrix. A highly ordered graphitic ribbon-like texture was developed within a few nanometers of the ablated surface of the carbon fibers with gaps between the ribbons. Crystallites in the form of a round hollow column were present in the matrix of the ablated surface. A ribbon like texture in the interface region near the side of the carbon fibers was observed.
酞菁铁固态热裂解制备新型炭纳米材料
ZHI Lin-jie, Ute Kolb, Klaus Müllen
2006, 21(02): 109-113.
Abstract(2051) PDF(1871)
Abstract:
Solidstate pyrolysis of iron phthalocyanine in a sealed system was investigated for the preparation of carbon with novel nanostructures. Straight and highly aligned carbon nanotubes (CNTs) were obtained in bulk quantity. Higher temperatures (>800℃) were beneficial to improve the growth of CNTs. By this procedure, long nanocables having an iron carbide core and a graphitic shell were fabricated. Carbon nanostructures with necklacelike and tubeintube architectures were prepared using this method.
利用感应加热技术进行炭纤维连续石墨化
WANG Hao-jing, LI Dong-feng, WANG Xin-kui
2006, 21(02): 114-118.
Abstract(2359) PDF(1563)
Abstract:
Large isotropic pyrolytic carbon rings were fabricated by a steady fluidized bed deposition apparatus with a rotating substrate. The microstructure of the isotropic pyrolytic carbons obtained was investigated by polarized light microscopy, SEM, TEM and XRD. Their mechanical properties were also studied. Observations using polarized light microscopy and SEM show that the microstructure is homogeneous and there is a small amount of closed porosity inside. TEM observations show that this material is mainly made up of fine turbostratic carbon structures. Mechanical tests show that the Young’s modulus, microhardness, flexural strength and compressive strength of the carbons are higher than those of traditional carbon materials.
大尺寸各向同性热解炭材料的制备与表征
WU Jun-feng, BAI Shuo, LIU Shu-he, XU Hong-jun, CHENG Hui-ming
2006, 21(02): 119-124.
Abstract(2543) PDF(1437)
Abstract:
Large isotropic pyrolytic carbon rings were fabricated by a steady fluidized bed deposition apparatus with a rotating substrate. The microstructure of the isotropic pyrolytic carbons obtained was investigated by polarized light microscopy, SEM, TEM and XRD. Their mechanical properties were also studied. Observations using polarized light microscopy and SEM show that the microstructure is homogeneous and there is a small amount of closed porosity inside. TEM observations show that this material is mainly made up of fine turbostratic carbon structures. Mechanical tests show that the Young’s modulus, microhardness, flexural strength and compressive strength of the carbons are higher than those of traditional carbon materials.
椰壳活性炭基超级电容器的研制与开发
ZHOU Peng-wei, LI Bao-hua, KANG Fei-yu, ZENG Yu-qun
2006, 21(02): 125-131.
Abstract(2626) PDF(1581)
Abstract:
In an attempt to develop small highpower supercapacitors a 1V-70F, 9cm3, coinshaped supercapacitor was fabricated using coconutshell activated carbon with a surface area of 1660m2/g and 6mol/L KOH as the electrolyte. The outer package was made from laminated aluminum foil covered with a nylon insulating layer. The electrochemical behavior was measured by constant current charge/discharge and electrochemical impedance spectroscopy. A specific capacitance of 79F/g was obtained. Results show that a specific power density of 170W/kg or 330 W/L, and a specific energy density of 1Wh/kg can be reached with an excellent discharge performance under high current density.
脉冲FCVI制备炭/炭复合材料的微观结构及力学性能
CHEN Qiang, LI He-Jun, ZHANG Shou-Yang, HAN Hong-mei, LI Ke-zhi
2006, 21(02): 132-138.
Abstract(2888) PDF(2585)
Abstract:
Felt based C/C composites were fabricated by an impulse forced flow thermal gradient chemical vapor infiltration technique. The micro morphologies and textural characteristics of the pyrocarbon and fracture surfaces were observed by polarized light microscopy and SEM. The mechanical properties of the composites were tested by bending experiments. Results showed that the density of the composites could be up to 1.7g/cm3 after 100h densification at 1000-1250℃. Further heat treatment at 2300℃ was carried out following densification. The flexural strength of the composites could reach 125.4MPa with a deflection of 0.61mm. The advantages of this technique were a high densification rate, uniform density and good mechanical properties. Densification temperature had a great impact on the microstructure. A higher temperature favored rough layer pyrocarbon while a lower temperature favored for smooth layer pyrocarbon, but a mixture was obtained in most cases because of complicated densification conditions.
膨胀次数对天然鳞片膨胀石墨微结构的影响
GAO Lin, GONG Yin-xiang, MA Ling
2006, 21(02): 139-143.
Abstract(2380) PDF(2417)
Abstract:
The changes of bulk density, specific surface area and microstructure of natural flake graphite after several expansions were studied by nitrogen adsorption, XRD and SEM. Results show that the differences in bulk density get smaller and smaller with increasing expansion time. The increase of specific surface area in the first expansion is much bigger than in following expansions. The lattice parameters of the graphite change very slightly, with d004 and d101 increasing by only about 0.2% and 0.4% respectively after five expansions. SEM images show that the expanded graphite appears like crumpled paper in an expanded state.
活性炭对扑热息痛的吸附行为和体外释放性能
LIANG Dong, LU Chun-xiang, LI Yun-lan, LI Yong-hong, YUAN Shu-xia
2006, 21(02): 144-150.
Abstract(2229) PDF(1450)
Abstract:
The adsorption by and release of paracetamol from activated carbon (AC) with different pore structures and surface chemical properties were studied. The pore structure, specific surface area, surface chemical properties and pH at the point of zero charge of the AC were tested with N2 adsorption, Boehm titration and mass titration respectively. An AC with high specific surface area, and abundant mesopores ranging between 2 and 11 nm, exhibited excellent adsorption performance to paracetamol. Its adsorption capacity was 358mg/g, and its total release rate was 7% in 12h. The adsorption capacity of an AC with wider pore size distribution was 281mg/g and its total release rate reached 27% in 12h. The paracetamol adsorption capacity was higher on the AC which had a higher content of surface oxygen groups and exhibited an acidic character.
先驱体转化法制备2D Cf/SiC-Cu复合材料及其性能
WANG Qi-kun, HU Hai-feng, JIAN Ke, CHEN Zhao-hui, ZHENG Wen-wei, MA Qing-song
2006, 21(02): 151-155.
Abstract(2338) PDF(1406)
Abstract:
In order to meet the working requirements of a solid rocket nozzle throat, the anti-ablative properties of 2D Cf/SiC composites have been improved by decreasing surface temperature by Cu boil off in ablative conditions. 2D Cf/SiC-Cu composites with different Cu contents (2.18vol%,4.86vol%,6.53vol %) were prepared via precursor infiltration and pyrolysis, and their mechanical and ablative properties were investigated. Results indicated that with increasing Cu content, the flexural strength decreased from 261.07MPa to 203.61MPa to 164.91MPa, and the fracture toughness also decreased from 13.4MPa·m1/2 to 12.5MPa·m1/2 to 11.8 MPa·m1/2. The composites all retained structural integrity after 30 seconds ablation in an oxyacetylene torch, but flexural strength decreased to 121.16Mpa to 140.23MPa to 122.87MPa, and the corresponding mass ablations were 0.036g/s, 0.050g/s and 0.064g/s. The 2D Cf/SiC-Cu composites have low density, high strength and low ablative loss compared with other throat materials.
废弃物基活性炭吸附性能的影响因素
XIE Li-ping, LIN Wei-gang, YANG Xue-min
2006, 21(02): 156-160.
Abstract(2913) PDF(1517)
Abstract:
Activated carbons were prepared by steam activation of pyrolysis products from three typical municipal solid organic wastes (MSOW), sawdust (S), paper (PA), plastics (PL) and their mixtures. Factors affecting their adsorbability were investigated. Results show that the adsorbability of MSOW based activated carbons increases with an increase of the ratio of S to PA under a constant fraction of PL, whereas the adsorbability decreases with an increase of the PL content at a constant ratio of S to PA. In addition, the adsorbability of MSOW based activated carbons exhibits a maximum with increasing pyrolysis temperature.
热解氛围对聚丙烯腈分离炭膜微结构的影响
QIU Ying-hua, WANG Tong-hua, SONG Cheng-wen, QU Xin-chun
2006, 21(02): 161-166.
Abstract(2210) PDF(1436)
Abstract:
The microstructure of a polyacrylonitrile (PAN) carbon membrane prepared under vacuum or Ar atmosphere was studied by FTIR、XRD and Raman analysis. The change of chemical structure and formation of crystallites during the pyrolysis were also investigated. Results show that intra chain cyclization, dehydration and denitrogenation occur during the pyrolysis. The microstructure of the PAN carbon membrane is transformed from a linear polymer to turbostratic carbon with increasing pyrolysis temperature. Compared with an Ar atmosphere, the pyrolysis of the PAN carbon membrane under vacuum has a low activation energy, i.e. the initial temperature of the pyrolytic reaction of a PAN carbon membrane can be decreased and the pyrolytic reaction rate can be accelerated under vacuum. In addition, the d002、Lc data of PAN carbon membranes prepared under vacuum are smaller while the La data are larger than those obtained under an Ar atmosphere. This indicates that the microstructural regularity of PAN carbon membranes prepared under vacuum are better than for those obtained under Ar, and structural defects and porosity are relatively large in the latter.
溶胶-凝胶和碳热还原法制备塔状SiC纳米棒
XU Wu-jun, XU Yao, SUN Xian-yong, LIU Ya-qin, WU Dong, SUN Yu-Han
2006, 21(02): 167-170.
Abstract(2134) PDF(1656)
Abstract:
Silicon carbide nanorods were synthesized by sol-gel and carbothermal reduction processing with TEOS (tetraethoxysilane), PVP (polyvinylpyrrolidone) as starting materials and Fe(NO3)3 as catalyst. The composition and morphologies of the resulting SiC were investigated by XRD,29Si MAS-NMR and TEM techniques. Results show that the morphologies of the resulting sample are tower likeβ-SiC nanorods which typically have a tower base width between 80nm and 100nm, a step layer thickness of about 10nm between two layers and a height from 0.4 to 1.0 micrometers. The corresponding selected area electron diffraction pattern indicates that the growth direction of the nanorods is parallel to [111]. It is believed that the SiC nanorods are formed by a kinetically controlled process catalyzed by Fe under a supersaturated CO vapor.
水下电弧放电法制备洋葱状富勒烯
GUO Jun-jie, WANG Xiao-min, LI Tian-bao, LIU Xu-guang, XU Bing-she, Ichinose Hideki
2006, 21(02): 171-175.
Abstract(2174) PDF(1383)
Abstract:
produced using arc discharge between pure graphite electrodes in water were investigated by HRTEM. Results indicate that OLFs with various cores can be synthesized, which have a high degree of graphitization with diameters ranging from 5 to 40nm. The yield and productivity of OLFs rise with increasing current density.
碳纳米管在超级电容器中的应用研究进展
WU Feng, XU Bin
2006, 21(02): 176-184.
Abstract(2873) PDF(1804)
Abstract:
Supercapacitors are a new type of energy storage device that has seen great improvement in recent years. Due to their hollow cores, high electrical conductivity and high specific surface area, carbon nanotubes (CNTs) are regarded as one of the most promising electrode materials for supercapacitors. In this paper, progress on the application of CNTs in supercapacitors is reviewed. The properties of CNTs, activated CNTs, CNT/metal oxide composites and CNT/conductive polymer composites as electrode materials are discussed. The specific capacitance of supercapacitors based on CNTs is not very high because of their low specific surface area. Chemical activation of the CNTs can greatly enhance their specific surface area and hence enhance their specific capacitance. Composites of CNTs and pseudocapacitance materials (metal oxides or conducting polymers), which possess the desirable properties of both components, are promising electrode materials for supercapacitors because of their low cost and good properties.
化学气相沉积与渗透过程中热解炭织态结构生成机理研究
ZHANG Wei-gang, K.J. Hüttinger
2006, 21(02): 185-192.
Abstract(2570) PDF(1973)
Abstract:
Carbon textures, as a function of methane pressure, obtained at 1100℃ by chemical vapor infiltration of a carbon fiber felt with a fiber volume fraction of 7% and a capillary diameter of 1.1mm, at different surface area/volume ratios of the substrate were characterized using the optical extinction and orientation angle. Significant texture changes with increasing methane pressure were attributed to the nucleation growth mechanism of carbon formation with growth dominating at lower pressures, and the increasing influence of the nucleation mechanism of carbon formation at higher pressures. Carbon textures resulting from the growth mechanism perfectly agree with the particle filler model. It is postulated that high textured carbon is formed from a gas phase with an optimum ratio of aromatic hydrocarbons (molecular particles) to small linear hydrocarbons (molecular filler), whereas medium and low textured carbon are deposited with an excess of either aromatic or small linear hydrocarbons. Most significant differences in texture formation between chemical vapor infiltration and deposition result from the much lower hydrogen partial pressures in infiltration because hydrogen diffuses to the surface of the porous substrate.