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Volume 51, Issue 8
Displaying 1-13 of 13 articles from this issue
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Masaaki Ito, Saburo Sano, Akihiro Tsuzuki, Akihiro Gotou, Yasuo Shibaz ...2004 Volume 51 Issue 8 Pages 565-569
Published: August 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe oxidation behavior of α-SiC powders at elevated temperature was studied by using a TG (thermo-gravimetry) analyzer. Oxidation reactions were observed at two temperature regions. First one is due to the oxidation of free carbon around 700°C, and the other is caused by the oxidation of α-SiC particle surface around 1000°C. The oxidation starting temperature and the amount of oxidation product (SiO2) depend on the size of α-SiC particles. It was found that the starting temperature of the oxidation decreases with the particle size. The amounts of oxidation product increase with the decrease of particle size as well. It is concluded that the oxidation rate at around 1000°C is constant since the values of oxidation amount per unit area is almost uniform independent of the particle size of α-SiC powders.View full abstractDownload PDF (332K) -
Min-young Jun, Masao Kaneko, Akira Yanagisawa2004 Volume 51 Issue 8 Pages 570-575
Published: August 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSTitanium has many outstanding characteristics such as light weight with a specific gravity of 4.5, high specific tensile strength, low elasticity and thermal expansion coefficient, excellent corrosion-resistance, biocompatibility, and electrical conductivity and others. It is therefore used in a wide variety of industries such as aircraft, chemical, ships, dental, battery electrode material and others. In particular, in the use of titanium for battery electrode material, because the surface area of electrode material needs to be made large to promote high energy and chemical reaction, fiber shapes are ideal. However, there exists no efficient method for fabricating titanium fibers as yet.
In this study, authors established the conditions for fabricating titanium fibers using hot water soluble resin coated coiled sheet shaving method. Using the titanium fibers obtained, we sintered secondarily processed non-woven material in a vacuum furnace, and confirmed that multiporous titanium fibers with a porosity of 75% to 88% can be produced.View full abstractDownload PDF (4230K) -
Masaru Kawakami, Osamu Terada, Koji Hayashi2004 Volume 51 Issue 8 Pages 576-585
Published: August 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIn other researchers' studies by HRTEM observation and XMA analysis on VC-doped WC-Co fine-grained hardmetal, the phenomenon that V segregated at total WC(0001)/Co interface was reported and such segregation itself was suggested to be the direct cause for V inhibition effect on WC grain growth. This suggestion, however, seemed to be inadequate, because it is not clear whether this segregation was generated by an equilibrium adsorption mechanism during the temperature-raising-stage and/or temperature keeping-stage of sintering, i.e., during the socalled grain growth-stages, or by a heterogeneous precipitation (hetero-epitaxial nucleation and growth) mechanism during the cooling-stage after the temperature keeping-stage.
In this study, the effect of the cooling rate on the amount of V segregation was investigated to solve the above problem. It was found that the amount depended on each WC grain even at a certain cooling rate and the arithmetic average amount became smaller with increasing cooling rate. These findings, a consideration on the basis of the general theory of grain growth in multi-phase system, etc., suggested the following. All of the V segregation at total WC(0001)/Co interface is not necessarily generated by an equilibrium adsorption mechanism, but mainly by the heterogeneous precipitation mechanism. Therefore, such V segregation itself should not be directly correlated to the VC inhibition effect on WC grain growth. The segregation, etc., however, suggested that V atoms adsorb and desorb intermittently at the step and/or kinks, i.e., WC growth site, of WC(0001) crystal surface and thus WC grain growth which occurs according to Ostwald-ripening mechanism is inhibited during the V adsorption and desorption.View full abstractDownload PDF (11299K) -
[in Japanese]2004 Volume 51 Issue 8 Pages 588
Published: August 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (91K) -
Development of New Functions by ExfoliationMichio Inagaki, Masahiro Toyoda2004 Volume 51 Issue 8 Pages 589-594
Published: August 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDesigning and control of structure and nanotexture of carbon materials are important factors to designing and control of their functions. Here, firstly a brief explanation of structure and nanotexture of carbon materials was presented and then the destruction of nanotexture was shown to open some new functions and applications of carbon materials by focusing "exfoliation"; exfoliated graphite had high sorption capacity for heavy oils and exfoliated carbon fibers gave high capacitance of electrochemical capacitors.View full abstractDownload PDF (3174K) -
Takashi Kyotani2004 Volume 51 Issue 8 Pages 595-602
Published: August 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSUsing uniform nano-channels of aluminum anodic oxide film as a template, uniform and unique multiwalled carbon nanotubes can be synthesized with a selectivity of 100%. This technique allows one to precisely control the diameters and the length of nanotubes. Moreover, this method makes them possible to chemically-modify only the inner surface of carbon nanotubes and to prepare carbon nanotubes with double coaxial structure of heteroatom-doped multiwalls. Metal or metal oxide filled nanotubes can also be synthesized by this method and highly-crystallized inorganic nano-rods or nano-ribbons cab be fabricated using the cavity of the carbon-coated nano-channels as a reaction field. In addition to one dimensional nano-carbons like carbon nanotubes, unique nano-porous carbon can be prepared by the template technique. Micro and mesoporous carbons with surprisingly regular ordering can be synthesized using zeolite and mesoporous silica templates, respectively. In this review, we introduce such template-mediated approach and highlight how useful and versatile the template technique is for the production of nano-carbons.View full abstractDownload PDF (7575K) -
Kazuhiko Oda2004 Volume 51 Issue 8 Pages 603-610
Published: August 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDLC film is a diamond like amorphous carbon film. It has excellent tribological properties and has been applied to the mechanical parts which need the high wear resistance and low friction. Many kinds of methods have been developed to deposit the DLC film. Lately, DLC film can be coated on several kinds of materials, and can be used for wider applications. In the fields of the tribology under the higher load, DLC film is now applicable to the cutting tools. DLC film can be applied to the rubber or the polymer substrate which are easily damaged by the thermal energy. From the viewpoint of the global environment protection, DLC film is developed to apply the automotive engine parts to improve the fuel economy. Furthermore, beside the tribological uses, new applications such as the gas barrier of the polymer are developed. New applications and new investigations are reviewed about the DLC film.View full abstractDownload PDF (5814K) -
Yasuyuki Yamaguchi, Masao Yukumoto2004 Volume 51 Issue 8 Pages 611-617
Published: August 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSAs society becomes more concerned about environmental protection and resource recycling, the refuse derived fuel (RDF) technology has been recognized as a new refuse disposal technology that replaces small-and medium-scale incinerators, and the number of RDF plants has been increasing. To promote more widespread use, manufactured RDF must be utilized. Lately the large-scale use of RDF power generation has been vigorously promoted in Mie and Ishikawa Pref. However, there are many problems such as cost efficiency and cooperation from neighboring municipalities, so it seems that it takes time to bring large-scale RDF plants into wide-spread use. Against this background, we have moved with the research and development of the carbonization system. In this system, RDF is heated and carbonized at about 1, 000 K in the absence of O2 or in a low-oxygen atmosphere using an oscillating type carbonization furnace. A demonstration plant with an RDF treatment capacity of 1 ton/h is brought into operation in April 2000 at Mizushima Works and test runs are being carried out for 30 days. The resulting carbide is used in the pulverized-coal injection for blast furnace and is mixed with raw materials for sintering. It is expected that the biomas carbonization system will come into widespread use at industry as one of the environmental application.View full abstractDownload PDF (3355K) -
Junichi Arima, Akinori Muto, Thllada Bhaskar, Yuusaku Sakata2004 Volume 51 Issue 8 Pages 618-621
Published: August 15, 2004
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSPorous carbons were prepared from different chemical structure resins used as carbon precursors. Styrene-divinylbenzene resin without ion exchange group (MR-type (1)) and with different contents -SO3 resins (MR-type (2), (3) and Gel-type) were used in this study. These resins were carbonized in N2 stream and activated in CO2 stream. Specific surface area and pore size distribution of the carbon materials depend on the physical and chemical structures of the raw materials. Micro porous carbon was prepared from high divinylbenzene content (100%) resin and micro and meso pore carbon from low divinylbenzene content (20%) with -SO3 groups. Micro and meso bimodal had higher capacitance (70 F/g) than only micro pore carbon (43 F/g) used for EDLC carbon electrode.View full abstractDownload PDF (344K) -
Effect of Carbon MaterialsRyusei Otsuki, Shoichi Nasu, Ryosuke Fujimori, Kinji Anada, Kentaro Oh ...2004 Volume 51 Issue 8 Pages 622-625
Published: August 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSEffects of carbon materials on weight yields of (C60+C70) and weight ratios of C60 to (C60+C70) in soot were examined by the Joule resistive heating of four kinds of carbon materials at He gas pressures from 0.7×104 to 8.0×104 Pa for collector radii of 45, 50 and 55 mm. The yields were in the range of 1 to 8% for graphite with hexagonal lattice, and better than those for glassy carbon. The most effective He gas pressures for the fullerene yields were in the range of 4.0 to 5.3×104 Pa. Any collector radii dependence of the yields was not observed. The weight ratios of C60 to (C60+C70) were about 60 to 70%, and showed neither He gas pressure dependence nor collector radii dependence for four kinds of carbon materials.View full abstractDownload PDF (275K) -
Effects of Gas SpeciesRyusei Otsuki, Shoichi Nasu, Kentaro Ohhashi, Ryoichi Yamamoto, Kimio ...2004 Volume 51 Issue 8 Pages 626-629
Published: August 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe He, Ar and the Penning gas pressure effects on the preparation yields of the fullerenes were investigated by means of the arc discharge method using graphite (PGX) anode buried in a tungsten rod and tungsten cathode for collector radii of 50mm. The maximum yield showed about 13-14% at 67kPa in He gas. The yields in the mixtures of He and Ne gases (the Penning effect) were similar to those obtained in He gas. Weight ratios of C60 to (C60+C70) were about 20% in Ar gas, while those in He and Penning gas were about 60%. Ultra sonic vibration was effective to separate C70 from soot.View full abstractDownload PDF (328K) -
Effects of Arc TemperaturesRyusei Ohtsuki, Shoichi Nasu, Kinji Anada, Ryosuke Fujimori, Kentaro O ...2004 Volume 51 Issue 8 Pages 630-632
Published: August 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSEffects of arc temperatures (arc positions) on weight ratios of C70 to (C60+C70) in fullerene production were examined by vaporization of graphite inserted in the cathode drop region and in the positive column region in helium (He) arc discharge between two tungsten electrodes. C70 were detected more than C60 in the soot prepared by both vaporizations under He arc discharge between two tungsten electrodes in He gas pressure range of 0.7×104 to 8.0×104 Pa. In addition, C70 were formed more than C60 near the arc position, that is, at higher temperatures than near the wall of the deposition bowl, that is, at lower temperatures.View full abstractDownload PDF (224K) -
Effects of Deposition TemperatureRyusei Otsuki, Shoichi Nasu, Masaki Matsushita, Kimio Fujii, Kentaro O ...2004 Volume 51 Issue 8 Pages 633-634
Published: August 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSWe examined effects of deposition temperatures and collector radii on the yields of fullerenes by arc discharge. Yields of fullerenes were 7-10%, 4 -6% and 0.5-1% in the liquid nitrogen-cooling, water-cooling, non-cooling, respectively, and were better with a collector radius of 50 mm than with that of 30 mm. The weight ratios of C60/C70 are about one for all runs of experiments.View full abstractDownload PDF (139K)
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