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Volume 1992 (1992)
- Issue 155 Pages 282-
- Issue 154 Pages 213-
- Issue 153 Pages 149-
- Issue 152 Pages 67-
- Issue 151 Pages 2-
Volume 1992, Issue 155
Displaying 1-21 of 21 articles from this issue
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Kazuyoshi Kuriyama1992 Volume 1992 Issue 155 Pages 282-287
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSA typical disordered carbon material, phenol-based activated carbon fibers, has been characterized by conductivity measurements and electron spin resonance (ESR) measurements. This carbon is well known as an excellent adsorbent with huge specific surface areas, however, another aspect i.e. electronic properties is focused in this paper. Since this material has a high ratio of surface atoms, interesting phenomena are expected to emerge from the surface states.
The results show that this carbon is an unusual insulator of which conductivity at room temperature is rather high (about 10S/cm). Although this material belongs to so-called hard carbon, an insulator-metal transition is found to take place at rather low temperatures between 1300-1500K. Corresponding to the transition, a fast spin relaxation is observed. A conventional microstructure model for disordered carbons, i.e., congregation of ultra fine powders, can well account for the insulating properties.View full abstractDownload PDF (2268K) -
Shiushichi Kimura, Aira Hotta, Sigenari Ohsawa, Kouichi Yasuda, Yohtar ...1992 Volume 1992 Issue 155 Pages 288-294
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSMicrostructural control of carbon fiber/carbon composites wasinvestigated by using high carbonyield pitches as matrix precursor, and by adding sulfur or carbon black to the precursor pitch. Using each precursor pitch the matrix carbon resulted in the flow-type microstructure where the carbon layers alligned extensively parallel to the carbon fiber axis, and hardly depended on the characteristics of the precursor pitch. However, the addition of sulfur or carbon black to the precursor pitch was effective in changing the matrix carbon into the fine mosaic microstructure where the size of the anisotropic region of the matrix carbon strongly depended on the characteristics of the precursor pitch and the type of the additives. These results suggested that the microstructure of carbon fiber/carbon composites with high carbon-yield pitch as matrix precursor could be controled by the addition of sulfur or carbon black.View full abstractDownload PDF (8314K) -
Minoru Shiraishi, Noriko Yoshizawa, Katsumi Ohkawa, Toyohiro Maeda1992 Volume 1992 Issue 155 Pages 295-300
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSActivated carbons with high surface areas ranging from 800 to 4, 000 m2/g (M8, M15, M30, M40), which were prepared by use of the reaction of carbonaceous mesophase spherules with KOH, were studied by transmission electron microscopy and X-ray diffraction. With an increase in the surface area of the carbons, microtextures are changed from an anisotropic discotic of the non-activated carbon to the microtexture consisting of both single sinuous layers and stacks of 2-3 layers with 1-2 nm in size. As a result of the penetration of KOH into the mesophase spherules, homogeneous large pores with over several tens nm in diameter are formed in M8 and M15 carbons having surface areas of 800 and 1, 500 m2/g, respectively. In these carbons, slit-like pores are also present between the stacks divided by the destruction of one or two layers and a small quantity of single sinuous layers is locally distributed. A carbon with the highest area of 4, 000 m2/g, M40 is composed almost all of the single sinuous layers and the small stacks, in which stacks more than 4 layers can not be observed. The extraordinarily high surface area in these carbons can well be explained in terms of the appearance of the single sinuous layers and the small stacks on activation.View full abstractDownload PDF (4265K) -
Takashi Kyotani, Naohiro Sonobe, Akira Tomita1992 Volume 1992 Issue 155 Pages 301-306
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSPolyfurfuryl alcohol (PFA) was carbonized between the lamellae of saponite (SAPO) clay which has a structure similar to montmorillonite. The carbon thus obtained was characterized and compared with the carbon previously prepared from (MONT). The carbon from SAPO is quite different from the MONT-carbon; i. e., the former is non-graphitizable and swells with organic solvents. The SAPOcarbon consists of very thin and wrinkled films. Such a unique structure of this carbon comes from three-dimensionally random structure of SAPO template. It was found that the presence of both the unique structure and surface oxygen-containing complexes on the carbon is necessary for the swelling with solvents.View full abstractDownload PDF (3294K) -
Keiko Nishikubo, Takeshi Imamura, Yasuhiro Yamada, Shigeji Hagiwara, M ...1992 Volume 1992 Issue 155 Pages 307-314
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe stabilized polyacrylonitrile (PAN) fiber being heat-treated in an atmosphere of nitrogen, black color material was formed at 1000-1200°C and white color material was formed at 1300-1400°C on surface of a graphite vessel.
The black color material was investigated with electron microscope; this material was observed as filamentous carbon of diameter 0.1-2μm, mainly about 0.5μm, which consisted of thin skin and many nodes such as a bamboo. A distance between two nodes was about equal to diameter or a little shorter than diameter. The thin skin of black color material was composed of 10 to 20-sheet carbon layers, of which interlayer spacing was about 0.34nm. The carbon layer of these skin and nodes was arranged such as a bag-like.
The white color material was identified as a silicon-nitride (Si3N4) filament of diameter about 1μm.View full abstractDownload PDF (9630K) -
Minoru Noguchi, Kohichi Miyasita, Morinobu Endo1992 Volume 1992 Issue 155 Pages 315-319
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSPPP (Poly Para Phenylene) heat-treated at various temperatures was evaluated as an anode of Lithium secondary battery. The specimen heat-treated at 973K showed discharge capacity of 370Ah/kg, close to that of LiC6, under the condition of 1.6mA/cm2 current density and +10mV-3V (vs. Li/Li+) charge-discharge terminate voltage.
From the results of several analytical methods including X-ray diffraction and laser Raman spectroscopy, this specimen can be defined as an intermediate material between organic compounds and inorganic carbons. Thus present heat-treated PPP is quite attractive in the applications of Lithium secondary batteries.View full abstractDownload PDF (1972K) -
Ken-Ichi Kondo, Hisako Hirai1992 Volume 1992 Issue 155 Pages 320-334
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSStudies on new carbon phases are reviewed from the point of view of non-equilibrium processing. First, phase diagram studies on carbon under high pressures and high temperatures are summarized in order of progress, and the known and the expected, unknown phases are listed as metastable phases sorted by bondings. Second, the SCARQ (shock compression and rapid quenching) by which we obtained new phases, n-diamond and 0.25-i-carbon, is introduced as a useful processing method to produce and to investigate new carbon phases. Third, we discuss the framework of how to investigate new carbon phases, comparing with common, essential factors in some non-equilibrium processes. We conclude that a cooling rate and constraint conditions are important and convenient to classify the processes.View full abstractDownload PDF (6508K) -
Takashi Aizawa, Yoshio Ishizawa1992 Volume 1992 Issue 155 Pages 335-346
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSMonolayer graphite can be grown epitaxially on transition metal carbide surfaces with very easy procedure. Surface periodicity, phonon dispersions, electron energy dispersions, STM image and so on were measured. Monolayer graphite has similar properties to pristine graphite, although the interaction between the graphite and the substrate is so large that it affects also intra-layer π bond. The surface becomes inert and stable once monolayer graphite is formed. In case transition metal carbides are applied to field emitter, the formation of monolayer graphite dramatically improves the current stability.View full abstractDownload PDF (5157K) -
Kazuo Miyasaka1992 Volume 1992 Issue 155 Pages 347-356
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSA substrate being hard to dye can be easily dyed a desire color, by applying a special dyebath containing concentrated sulfuric acid. All inorganic and organic materials may be instantly dyed a desire color, so far as those having a greater surface area are concerned.
The substrates being most hard to dye such as carbon black, polypropylene, polyvinyl chloride, polyvinilidene chloride, etc., may be quickly dyed a beautiful color, by this dyeing process.
Insoluble coloring materials, such as vat and sulfur colors, or pigments, are the most suitable for this process. These can be applied as molecular solutions. Therefore, a beautiful color can be satisfactly developed. Also, this new dyeing process can be applied to soluble coloring materials. In this case, an organic acid is useful as a component in the dye bath.
A special dyebath consisting of concentrated sulfuric acid and with the regular amounts of surface active agent and organic solvent which have an emulsified state may be used effectively for quick dyeing on the most hard to dye. This special dyebath has a greater dye-accessibility for the substrates being hard to dye.View full abstractDownload PDF (3439K) -
Pierre Ehrburger, Eric Dallies-Labourdette1992 Volume 1992 Issue 155 Pages 359-364
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe effect of a thin silica coating on the oxidation of carbon fibres has been investigated in the temperature range 600-1200°C. Silica was deposited by thermal cracking of an organic precursor (tetraethoxysilane). The protection of carbon fibre by the coating consists first in an almost complete, but limited in time, resistance to oxidation. Thereafter, oxidation of the carbon becomes noticeable, but at a smaller rate than for the uncoated fibre. The change in efficiency of theprotection during oxidation are discussed in terms of modification of surface properties of the carbon, total surface area and active surface area, and of thermomechanical characteristics of the carbon-coating interface.View full abstractDownload PDF (1940K) -
Toshikuni Yonemoto, Hiroaki Nitta, Teiriki Tadaki1992 Volume 1992 Issue 155 Pages 365-369
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSOxidative stabilization of petroleum derived mesophase pitch fiber under increasing temperature conditions was simulated through the use of a kinetic model in which the mass transfer of the oxygen molecules and the autoxidation reaction with the active site in the fiber were taken into account. Temperature dependence of physicochemical parameters such as the effective diffusivity of oxygen molecules in the fiber, the reaction rate constant and the gas-solid equilibrium coefficient of oxygen molecules, were introduced into the mathematical model. The validity of the kinetic model and the numerical calculations was ascertained by comparison of the theoretical values forthe outlet concentration of oxygen gas and the rate of oxygen consumption by the fibers with experimental values. The stabilization reaction was completed prior to the entire consumption of activesites in the fiber, and fixed oxygen was considered to be non-uniformly distributed in the direction of the fiber radius.View full abstractDownload PDF (499K) -
Isao Mochida, Yozo Korai, Kiyoyuki Shimizu, Seong-ho Yoon, Ryuji Fujiu ...1992 Volume 1992 Issue 155 Pages 370-378
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSPreparation, structure, properties and a variety of application of mesophase pitches from aromatic hydrocarbons are reviewed to clarify their unique natures in the carbon science and technology. HF/BF3 catalyst oligomerizes a variety of aromatic hydrocarbons into oligomers ranging dimers to decamers, which carry naphthenic hydrogens produced through aryl-aryl coupling. The mesophase pitches can exhibit a variety of properties, reflecting their starting structure and polymerization conditions. For example, softening points of 100% anisotropic pitch range from 210 to 300°C. The mesophase pitches shows excellent carbon yields of 80-90% under atmospheric pressure and over 90% under 3.1 MPa. High reactivity for oxidation in the air and thermal stability under inert atmosphere are additional advantage of the present pitch. Such properties allow a number of their applications for the carbon fiber, carbon tape, composites, high density carbon, porous carbon composite and carbon ceramic composite. Such products exhibited excellent mechanical properties by facile preparation procedure, reflecting the unique properties of the present mesophase pitches whichare now available by a large quantity at a reasonable price.View full abstractDownload PDF (3548K) -
Takeshi Ehara, Haruo Kumagai, Yuzo Sanada1992 Volume 1992 Issue 155 Pages 379-385
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe surface of carbon fiber is one of key properties of composite material with carbon fiber. Interactions between carbon fiber and pitch over the range of carbonization temperature were investigated by in-situ electron paramagnetic resonance (e.p.r.) method.
From in situ e.p.r. measurements for carbon fiber added pitch, the results are summarized as follows: (1) Peak to peak line width of e.p.r. spectra for Si (petroleum pitch derived fiber carbonized at 873K) /Pitch systems and P2 (PAN derived fiber carbonized at 1173K) /Pitch systems was characteristic at the ambient temperature lower than 673K. These characteristics were not influenced by kinds of pitches.(2) Unexpected evidences were found that (i) no obvious differences of the spin concentration between experimental and calculated values for CF/Pitch systems up to 673K, (ii) at the ambient temperature higher than 673K, experimental values of spin concentration were lower than calculated ones. Especially S1/Pitch I (isotropic pitch) and P1 (PAN derived fiber carbonized at 873K) /Pitch A (anisotropic pitch) systems were remarkable.
The spin concentrations depended upon the combination of carbon fiber and pitch.(3) Clear relationship between the spin concentration of carbon fiber added pitch and the degree of graphitization of the carbon fiber was found.View full abstractDownload PDF (755K) -
K.S. Yang, K.H. An, K.W. Yang, H.B. Lee, T.W. Son, W.E. Lee, Y.H. Kook1992 Volume 1992 Issue 155 Pages 386-392
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSMesophase pitches derived from naphthalene and anthracene were prepared in the presence of a Lewis acid, AlCl3, with varying the reaction conditions. The C/H ratio of naphthalene pitches increased with an increase in temperature and naphthenic groups were introduced into pitches in the early stages of the reaction. At rather severe conditions, alkyl groups were introduced. The film formed from naphthalene showed unidirectional orientation. On the basis of the experimental results, the reaction mechanisms foi the condensation of the naphthalene were proposed as cationic polymerization in the earlier stage and radical polymerization in the later stage.View full abstractDownload PDF (1554K) -
Tsuyoshi Nakajima1992 Volume 1992 Issue 155 Pages 393-397
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe synthesis, electrical conductivity and stability of fluorine-intercalated carbon fibers have been summarized. Stage 1 to 4 compounds, C3F-C16F, are synthesized according tothe crystallinity of host carbon fibers and reaction conditions. With increasing crystallinity of carbon fiber, and with increasing acidity of a coexisting solid fluoride and amount of coexisting HF, fluorine intercalation is facilitated. The highest electrical conductivities were (8-9) ×103, 2.4×104 and 1.1×105 Scm-1 for fluorine-intercalated PAN fiber, pitch fiber and vapor grown carbon fiber (VGCF), respectively. The stability was in the order of the compounds of PAN fiber, pitch fiber and VGCF.View full abstractDownload PDF (513K) -
Isao Mochida, Ryuji Fujiura, Yozo Korai1992 Volume 1992 Issue 155 Pages 398-402
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSPrepregs of carbon fiber cloth and mesophase pitch catalytically synthesized from naphthalene were prepared by simple procedures. The present mesophase pitch of high fluidity penetrated smoothly into carbon fiber cloth at 300-340°C, leaving very few void. The prepregs after heattreatment at 450°C for 30 min adhered well each other by the carbonization in the laminated form, providing extremely high carbon yield over 97 wt%. The oxidative stabilization at 220°C for 9h completely prevented the melt flow of the pitch in the prepreg during the carbonization, its high reactivity to oxygen being definite. The properties of the mesophase pitch required as a binder for the prepreg of the present form were found to be controllable through the thermal or oxidative condensation of the mesogen molecules.View full abstractDownload PDF (3860K) -
Resourceful Utilization Technologies of PitchYuji Matsumura, Toyohiro Maeda1992 Volume 1992 Issue 155 Pages 403-406
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSSeveral new carbon materials have been developed in Osaka Gas Co. Ltd. so far. Especially, the general purpose carbon fibers and the activated carbon fibers have already been commercialized. The other advanced carbons such as the pitch fluoride, the carbon film, and the super activated carbon have also been investigated. In this paper, we present some attractive features and applications of these newly developed carbon materials.View full abstractDownload PDF (1639K) -
Jae-Hyun Liew, Yong-Gun Shul, Tae-Hee Lee, Seung-Kon Ryu, Bo-Sung Rhee1992 Volume 1992 Issue 155 Pages 407-410
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSA mixture of activated carbon fiber (ACF) and acetylene black was employed as a catalyst support material for the electrode of phosphoric acid fuel cell and its cathode performance was examined in a half cell of 100% phosphoric acid electrolyte at 190°C. Platinum particles loaded on this hybrid electrode were proved to be less than 2.5 nm in size. As the ratio of ACF to acetylene black changed to 10, 20, 30, 40 and 50%, the corresponding cathode performance showed 972, 1143, 928, 909 and 723 mA/cm2 at 700 mV, respectively.View full abstractDownload PDF (1960K) -
C.J. Kim, S.J. In, Y.G. Jo, S.K. Ryu, B.S. Rhee1992 Volume 1992 Issue 155 Pages 411-416
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSMesophase pitches which have different amount of mesophase were prepared and separated into mesophase and isotropic phases by a high-temperature centrifugal method . Properties of mesophase during formation, growth, and coalescence of mesophase spheres were investigated by measuring the solubility, density, X-ray diffraction, and thermogravimetric analysis.
QI was the main component of smaller mesophase spheres, and the β-resin of the isotropic matrix contributed to the growth of spheres. The density and C/H atomic ratio of mesophase were nearly constant at 1.385 g/cm3 and 2.00, respectively, during heat-treatment. The amount of functional groups of bigger spheres was larger than smaller spheres or bulk phase . Bigger spheres have better crystallite structure than smaller spheres or bulk phase.View full abstractDownload PDF (2350K) -
J.J. McHugh, G.Z. Liu, D.D. Edie1992 Volume 1992 Issue 155 Pages 417-425
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSNaphthalene-based mesophase, supplied by Mitsubishi Gas Chemical Co., Inc., (under the commercial name “AR” mesophase) and a heat-soaked mesophase pitch were melt-spun into fiberform using a pilot-scale extruder. The oxidation conditions of the as-spun fibersformed from each mesophase were optimized (based on tensile strength), and all fibers were graphitized at 2400°C. The naphthalene-based mesophase was found to be more spinnable, despite the fact thatits viscosity was more temperature-dependent than that of the heat-soaked mesophase. Also, fibers formed from the naphthalene-based mesophase were found to stabilize more rapidly than those formed from the heatsoaked mesophase. After carbonization, the naphthalene-based mesophase fibers exhibited much higher tensile strengths and moduli than equal-sized fibers produced from heat-soaked mesophase. The naphthalene-based mesophase fibers also exhibited lower electrical resistivities. Wide angle X-ray diffraction showed that the naphthalene-based mesophase fibers developed a smaller average interplanar spacing of the graphite basal planes and a larger average crystallite size than the heat-soaked mesophase pitch-based fibers.View full abstractDownload PDF (2433K) -
Kensuke Okuda1992 Volume 1992 Issue 155 Pages 426-429
Published: November 30, 1992
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSConcrete-based materials reinforced with carbon fibers have been extensively used in the construction industry in Japan. The existing conditions of the application of themare reviewed.View full abstractDownload PDF (1885K)
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