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Volume 52, Issue 2
February
Displaying 1-11 of 11 articles from this issue
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Paper
Paper
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Eiichi Sentoku, Keigo Yamada2005 Volume 52 Issue 2 Pages 71-78
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSMachinable ceramics can be shaped by cutting, drilling and tapping with commercial tools. The purpose of this paper is to study the influence of tool geometry on machined surface and chipping size in ceramics drilling. The cutting performance of machinable ceramics is investigated and discussed from the viewpoint of the relation among tool wear, roughness of the machined surface and chipping size on the exit side in the hole. The experiment of drilling machinable ceramics were carried out with twist drill of high speed steel by drilling machine.
The main results obtained were as follows: (1) The chipping in the hole exit side decreased in low cutting speed and low feed in the drilling. (2) The chipping decreases at 75° (MMC material) drill point angle or 90° (Si3N4-BN MC material). (3) Si3N4-BN MC was smaller than MMC for abrasion and steady abrasion and abrasion initial stage drilling. (4) The progress of the tool wear increases the chipping in the hole exit side.View full abstractDownload PDF (1278K) -
Hideki Oginuma, Katsuyoshi Kondoh, Takashi Yamaguchi, Eiji Yuasa2005 Volume 52 Issue 2 Pages 79-83
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSThe solid-state reaction to form Mg2Si bulk materials by spark plasma sintering (SPS) process was discussed. Elemental powder mixture of Mg-33.33 mol% Si was refined and consolidated as green compacts by repeated plastic working (RPW). SPS was performed to synthesize and sinter Mg2Si at 1123 K using the RPWed compact. Peaks of Mg2Si, where was neither of Mg nor of Si, were solely detected by X-ray diffraction analysis. Mg2Si bulk began to shrink above 800 K during SPS process, and it was densified significantly. The relative density of SPSed Mg2Si bulk material sintered at 1123 K reaches to almost 100% of the calculated density.View full abstractDownload PDF (1102K) -
Hirotaka Kato, Masaki Kato, Yuusuke Taguchi, Kazuo Washida2005 Volume 52 Issue 2 Pages 84-88
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSCu-Sn sintered materials were developed by utilizing bronze chips. The bronze chips, which were produced by dry-turning of BC3 bar, were mixed with electrolytic copper powder and atomized tin powder. The mixed powders were cold-compacted and then sintered without pressure. The limit of mixing amount of the chips to produce green compacts increased as the size of chips decreased. The effects of size and mixing amount of the chips on the density, microstructure and mechanical properties of the sintered specimens were investigated. It was found that the sintered density and mechanical properties increased as the mixing amount of chips increased up to 10 mass%, but decreased slightly above 10 mass%. There was no significant influence of size of chips on the sintered density. Cu-10 mass% Sn-20 vol% graphite sintered composites, which contained not only the bronze chips but also copper-coated graphite powder, showed low wear and friction under dry sliding conditions.View full abstractDownload PDF (1147K) -
Youn-Che Kim, Shoji Goto2005 Volume 52 Issue 2 Pages 89-96
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSIn order to investigate behavior of abnormal expansion of the iron-copper compacts, we compared the dilatometric curves of the compacts of the iron and the copper powders mixture with those of compacts which mixed the copper powder to the iron-copper alloy-powder. The dilatometric curves were obtained under the sintering conditions, which heated up to 1423 K by the heating rate of 1.66×10-1 K/s, held for 3.6 ks at 1423 K and cooled down at a rate of 3.33×10-1 K/s to room temperature.
The dilatometric curves of the compacts showed the different expansion behavior at temperatures above the copper melting point in spite of same chemical composition. All of the compacts of former case showed large expansion, but all of the compacts in latter case showed large contraction. The microstructures of sintered compacts also showed the different progress in alloying of the copper into the iron powder. Namely we could observe the segregation at alloy part of copper into iron powder in case of the sintered-compacts, which mixed the copper powder to the iron powder, but could not observe the segregation in compacts which mixed the copper powder to the iron-copper alloy-powder. But the penetration of liquid copper into the interstices between solid particles was occurred at both cases. Therefore, the showing of the different dimensional changes in the compacts in spite of same chemical composition is due to the alloying of copper into iron than the penetration of liquid copper into the interstices between solid particles.View full abstractDownload PDF (1424K) -
Katsuhiko Ueda, Terufumi Machida2005 Volume 52 Issue 2 Pages 97-106
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSThe effect of powder lubrication and mechanical properties on room temperature and warm compacting behavior has been investigated by examining various kinds of metal powders. Compacting process is modeled by analyzing the compacting behavior based on the punch load-stroke diagram.
It is understood that the model of the punch load-stroke diagram is composed of straight line (Stage I: powder flow), hyperbolic curve (Stage II: plastic deformation or fracture) and straight line (Stage III: bulk elastic strain). Larger or more spherical particles having lower friction allow lower pressure compacting in Stage I. In stage II, lower elastic modulus and yield point, higher ductility and n-value, and lower surface friction of particles are effective to allow lower pressure compacting.
It is confirmed that the method of die wall lubrication is better than powder lubrication to obtain higher density, though the latter method is suitable for green compacts with regular configuration under lower compacting pressure. Warm compaction enhancing good lubricating effect significantly affects decreasing compacting pressure through stage I and II. The compacting pressure is effectively reduced to get higher density only when powder particle indicates lower yield point and higher ductility.View full abstractDownload PDF (1886K)
Special Issue: Smart Carbon Materials
Summarization
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Yusaku Sakata2005 Volume 52 Issue 2 Pages 108
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSDownload PDF (110K)
Review
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Mineyuki Arikawa2005 Volume 52 Issue 2 Pages 109-114
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSRecently Nano-technology is one of the most popular topics, and Nano Carbon material is said to be the technology that is the nearest to the business. Both Fullerene that is the cage shape carbon molecular, and Carbon Nano Tube that is the tube shape of carbon structure, have already reached to the industrial stage. In this overview, the latest development and information about Fullerene production and application are explained.View full abstractDownload PDF (1328K)
Paper
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Mamoru Omori, Akira Okubo, Toshiyuki Hashida, Kazuyuki Tohji2005 Volume 52 Issue 2 Pages 115-119
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSThe multi-walled carbon nanotube (MWNT) was not consolidated without additives by the spark plasma system (SPS). The phenol resin of 33 wt% was added to promote the consolidation. The MWNTs were aligned perpendicular to pressing direction of SPS in the consolidated compact. Bulk density and Young's modulus were more than 1.7 g/cm3 and 10 GPa for the MWNT consolidated at 120 MPa at 1200°C and 1400°C. The fracture behavior on bending test was a kind of quasiplastic deformation and was based on pull out of the MWNTs.View full abstractDownload PDF (1979K) -
Risa Hirayama, Katsuhiko Mizuno, Jun'ichi Hayashi, Katsuhiko Muroyama2005 Volume 52 Issue 2 Pages 120-123
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSThe phenol-formaldehyde resins with various degrees of cross-linking were prepared by changing the formaldehyde/phenol molar ratios (F/P). The influence of the ratio (F/P) on the structure of the prepared resin was examined by using thermogravimetric analysis (TG) and FT-IR. It was found that an increase of the ratio (F/P) leaded to large oligomer and a promoted cross-linking. And the activated carbons were prepared from these resins with CO2-activation in order to examine the influence of the resin structure on the pore structure of the prepared activated carbon. There is little difference between the activated carbon prepared from high F/P ratio resin and one from low F/P ratio in the specific surface area and pore volume. However, the pore size distribution of the activated carbon prepared from the low F/P ratio resin was sharper than that of the activated carbon prepared from the high F/P ratio resin. It was deduced that this difference was caused by the difference in the crystallite size.View full abstractDownload PDF (420K) -
Masamichi Miki, Takeyuki Kikuchi, Shinji Inada, Michitaka Suzuki, Jun ...2005 Volume 52 Issue 2 Pages 124-130
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSElectromagnetic wave absorption characteristics, electrical resistivity and micro pore structure (specific surface area and micro pore size distribution) of the powder-method woodceramics, which were prepared by carbonizing the compacted mixtures of wood powder and 10-30 mass% of phenolic resin powder, were examined in comparison with those of the conventional MDF-method woodceramics, which were prepared by carbonizing the medium density fiber (MDF) boards impregnated with phenolic resin solution. The powder-method woodceramics carbonized at 650°C showed remarkable electromagnetic absorption characteristics as same as MDF-method woodceramics, namely the absorption values of 10%, 20% and 30% phenolic resin specimens were 35 dB at 11 GHz, 40 dB at 9 GHz and 50 dB at 2 GHz, respectively. These remarkable absorptions were mainly due to the suitably high electrical resistivities (101-103 Ωcm) of these woodceramics. The specific surface area of these woodceramics became to the maximum in the case of the carbonization at 700°C, namely 380 m2 · g-1 in the 30% phenolic resin powder specimen, 300 m2 · g-1 in the MDF specimen and 230 m2 · g-1 in the 10% phenolic resin powder specimen, respectively.View full abstractDownload PDF (1147K) -
Mikio Ito, Hideaki Ueda, Yasufumi Tsuji, Shigeta Hara, Atsushi Ueda2005 Volume 52 Issue 2 Pages 131-135
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSCarbon-related materials have been a potential candidate as a new hydrogen storage material. In this study, kish graphite powder, which is a low-cost carbon material produced through the steelmaking process, was mechanically milled under H2 atmosphere, and its dehydrogenation properties were investigated. The layer structure of kish graphite was mostly destructed after milling for 20 h, and contamination of Fe and stainless steel from a stainless steel vial and balls occurred. The mechanical milling was effective for increasing hydrogen content in the powder and decreasing hydrogen desorption temperature, and there were three desorption peaks in the TDS (thermal desorption spectroscopy) curve of the sample milled for 20 h. It was also found that V and Fe addition reduced the dehydrogenation temperatures and enhanced dehydrogenation corresponding to the second peak in the TDS curve.View full abstractDownload PDF (495K)
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