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Volume 53, Issue 12
December
Displaying 1-13 of 13 articles from this issue
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Paper
Paper
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Koji Seimiya, Makoto Sugamata, Ludwik Blaz, Junichi Kaneko2006 Volume 53 Issue 12 Pages 899-908
Published: 2006
Released on J-STAGE: May 08, 2007
JOURNAL OPEN ACCESSWith a purpose of obtaining materials of high specific strength at room and high temperatures, Al-8at%Mg mixed powder was mechanically alloyed with addition of oxide powders (GeO2, SnO2, PbO) of the Group IV elements of the periodic table. Solid state reactions during mechanical alloying (MA) and subsequent thermomechanical processing were studied. The MA powders were consolidated to the P/M materials by vacuum hot pressing and hot extrusion, and their solid state reaction and mechanical properties were studied. It was observed by X-ray diffraction that PbO was decomposed during MA, while GeO2 and SnO2 were decomposed during hot pressing. Reduced Ge and Sn were combined with Mg to form Mg2Ge and Mg2Sn, while reduced Pb remained as metallic Pb. Preferential oxidation of solute Mg occurred resulting in formation of MgO and MgAl2O4. The P/M material of Al-Mg-GeO2 system is harder and more ductile than those of Al-Mg-SnO2 and Al-Mg-PbO systems. The P/M material of Al-Mg-GeO2 showed the highest tensile strength of 629 MPa at RT and 361 MPa at 473K.View full abstractDownload PDF (2101K) -
Yukio Makino, Takuya Nakanishi, Hidenori Saito2006 Volume 53 Issue 12 Pages 909-914
Published: 2006
Released on J-STAGE: May 08, 2007
JOURNAL OPEN ACCESSRadial homogeneity in the pulsed high current sintering was estimated by consolidation behavior of anatase nano-powder with 9nm and the change of its crystallite size and preferential orientation. Radial distributions of density, crystallite size and the degree of preferential orientation showed a concave curve with a minimum at the central position against radial distance. It is suggested that the concave distributions arise from the corresponding distribution of current density.View full abstractDownload PDF (1013K) -
Shigefumi Kihara, Ryota Tada, Hiroki Yoshii, Masahiro Yamashita, Masay ...2006 Volume 53 Issue 12 Pages 915-920
Published: 2006
Released on J-STAGE: May 08, 2007
JOURNAL OPEN ACCESSThe paper describes the requirements to which ZnO evaporates without being fractured while laser is radiated. The fracturing phenomenon is mechanically evaluated. By executing a laser radiation test, the influence of relative densities on the fracture are investigated. It is shown that ZnO sintered billet with the relative density from 0.6 to 0.8 evaporates without being fractured while the laser is radiated. The billet was sintered by hot press. The sintering condition to obtain the ZnO sintering billet with the relative density from 0.6 to 0.8 is restricted within a range of 850°C to 1000°C under the sintering pressure 10MPa. The condition is restricted within a range of 800°C to 900°C under sintering press 15Mpa, whereas that is 800°C under sintering press 20MPa. Microscopic thermal stress and fracture stress appearing in peripheries of the porosity in the sintering billet were calculated by the homogenization method. Since the fracture stress is lower than the thermal stress of billet less than approximately 0.8 of the relative density, the produced billet is not fractured while laser is radiated.View full abstractDownload PDF (833K) -
Takashi Ando, Yoshio Harada2006 Volume 53 Issue 12 Pages 921-927
Published: 2006
Released on J-STAGE: May 08, 2007
JOURNAL OPEN ACCESSAs part of our study to find the optimal high Cr-Fe alloy powder spray for plasma spray coatings on the inner surface of Al cylindrical containers for high-temperature type NAS batteries, the relationship among the shape of the powder, the powder feed amount and the mass of deposit per unit area of powder was studied. The characteristics and sulfide corrosion resistance of spray coatings formed with different powder shapes was also studied. As a result, it was found that the shape of the powder greatly affects the powder feed amount and the mass of deposit per unit area. Granular powder has a better feed rate than flake powder, resulting in a greater feed amount. This contributes to a faster coating speed and the forming of an even coating thickness. It was confirmed that the physical properties of the optimal spray powder for mass production of NAS batteries is an apparent density of over 3.0g/cm3 and a flow rate under 30 s/50 g.
It was found that the surface of the spray coating formed using granular powder contain high amount of Cr oxide fumes. However, the coating had a good coating structure with fine laminate formation made up of layers of flat particles. It was concluded after a five-year charge/discharge test that NAS batteries sprayed with a 75 mass% Cr-Fe alloy powder have good corrosion resistance and good anticorrosion properties.View full abstractDownload PDF (1576K) -
Kazuhiro Matsugi, Gen Sasaki, Osamu Yanagisawa2006 Volume 53 Issue 12 Pages 928-937
Published: 2006
Released on J-STAGE: May 08, 2007
JOURNAL OPEN ACCESSThe spark sintering technique was utilized to produce high performance compacts consisting of (1) metal, W, Ti; (2) carbides, WC, Cr3C2; (3) oxide, Al2O3; or (4) sulfide, WS2; using their powders which were electroless Ni or Sn plated as their surface treatment. The sintered compacts produced from the electroless plated powders showed excellent mechanical and oxidation properties which were evaluated by Charpy impact, tensile, hardness, friction and high temperature oxidation tests, compared with compacts produced by elemental powder blending method. As the alloying or binder element, Ni or Sn was plated uniformly on the surfaces of some powders, which resulted in the successful achievements as follows: (1) the excellent sinterability, high densification rate and enough promotion of sintering, by production of the path for electrical current flow, uniform deformation in the homogeneously distributed soft binder phase and enough diffusion between binder and mother elements, and (2) the excellent mechanical and oxidation properties by the microstructural control such as homogeneous structure and composition through compacts under microalloying condition.View full abstractDownload PDF (1234K) -
Tadahiro Wada2006 Volume 53 Issue 12 Pages 938-942
Published: 2006
Released on J-STAGE: May 08, 2007
JOURNAL OPEN ACCESSThe tool life in turning of sintered steel is shorter than that of carbon steel. In order to determine an effective coating film for cutting sintered steel with a coated cemented carbide tool, the tool wear was experimentally investigated. Sintered steel was turned with physical vapor deposition (PVD) coated cemented carbide tools. The coating films used were (Ti, Al)N coating film and titanium-tungsten based coating films, namely (Ti, W)N, (Ti, W)C and (Ti, W)(C, N) coating film. (Ti, W)N, (Ti, W)C or (Ti, W)(C, N) is a new type of coating film. The following results were obtained: (1) The critical load of titanium-tungsten based coating films was higher than that of the (Ti, Al)N coating film. (2) The hardness of the (Ti, W)C coating film was similar to that of the (Ti, Al)N coating film. (3) In cutting sintered steel, the wear progress of the (Ti, W)N coated tool was similar to that of the (Ti, Al)N coated tool. (4) In cutting sintered stainless steel, the wear progress of the (Ti, W)N coated tool was slightly faster that of the (Ti, Al)N coated tool.View full abstractDownload PDF (535K)
Rapid Communicatin
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Ryuhei Yoshida, Yoshikazu Suzuki, Susumu Yoshikawa2006 Volume 53 Issue 12 Pages 943-946
Published: 2006
Released on J-STAGE: May 08, 2007
JOURNAL OPEN ACCESSEffect of HCl treatment on the hydrothermally prepared titanate nanotubes was studied. The pH and repeating times of acid treatment influenced both the microstructure and residual Na concentration of the titanate nanotubes. The lower pH and repeated acid treatment decreased residual Na ions in the titanate nanotubes, however, the acid treatment at much lower pH (pH 1) damaged the surface of nanotubes. The titanate nanotubes with almost no residual Na ions (i.e., less than the lower limit of detection by energy dispersive X-ray spectroscopy) can be obtained by hydrothermal method at 120°C for 72 h and H2O wash and subsequent HCl treatment at pH 2 for 3 times. The Na-free nanotubes (H2Ti3O7) were thermally unstable, and they changed into anatase particles at 500°C.View full abstractDownload PDF (791K)
Special Issue:Smart Carbon Materials
Summarization
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Akinori Muto2006 Volume 53 Issue 12 Pages 948
Published: 2006
Released on J-STAGE: May 08, 2007
JOURNAL OPEN ACCESSDownload PDF (122K)
Paper
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Masamichi Miki, Makoto Ohbayashi, Kenichi Hasegawa, Takeyuki Kikuchi, ...2006 Volume 53 Issue 12 Pages 949-954
Published: 2006
Released on J-STAGE: May 08, 2007
JOURNAL OPEN ACCESSElectromagnetic wave absorption characteristics and electrical resistivity of the 3∼5 mm thick ceramic specimens containing 14∼20 mass% of Bincho-charcoal powder and 4∼8 mass% of carbon black powder were measured by free space method and four probe method, respectively. The 3∼5 mm thick specimens containing 16% of Bincho-charcoal powder absorbed remarkably (about 30 dB) the electromagnetic waves of 4∼7 GHz. The 3∼5 mm thick specimens containing 5% of carbon black powder absorbed excellently (25∼40 dB) the electromagnetic waves of 4∼8 GHz. The electrical resistivities of the specimens containing16% of Bincho-charcoal powder and 5% of carbon black powder were 5×103 Ω·cm and 1×104 Ω·cm, respectively.View full abstractDownload PDF (829K) -
Ryusei Otsuki, Kentaro Ohhashi2006 Volume 53 Issue 12 Pages 955-959
Published: 2006
Released on J-STAGE: May 08, 2007
JOURNAL OPEN ACCESSBiCl3 and CuCl2 reacted with HOPG (Highly Oriented Pyrolytic Graphite) in the various conditions. In the reaction of BiCl3 with CuCl2GIC, the only stage4 BiCl3GIC was obtained. In the reaction of CuCl2 and BiCl3 with HOPG, the coexistent substance of stage2 or 4 BiCl3GIC and stage2 or 4 CuCl2GIC was obtained. Composition of Cu and Bi was C20(CuCl2)0.74(BiCl3) in the case of mol ratio CuCl2:BiCl3=6:1 with the vacuum tube reaction, and was C11.76(CuCl2)2.08(BiCl3) in the case of 3:1.View full abstractDownload PDF (1095K) -
Yusuke Okano, Hiroki Sakurai, Toshiki Nakamura, Kentaro Ohhashi2006 Volume 53 Issue 12 Pages 960-964
Published: 2006
Released on J-STAGE: May 08, 2007
JOURNAL OPEN ACCESSIn order to improve pinning properties of bulk Bi2Sr2Ca2Cu2Oy (Bi2223) materials, samples of both pure Bi-2223 and Bi2223 with carbon nanotubes (CNT) embedded have been prepared by solid state reaction method. The parent samples mixed with 0∼5wt% of CNT were heated at 800°C for 24h in air or N2 atomosphere. We could not find any great improvement of critical current density Jc due to reduction property of CNT.View full abstractDownload PDF (666K) -
Shunsuke Yamanaka, Hokuto Kadokura, Akira Kawasaki, Hiroki Sakamoto, Y ...2006 Volume 53 Issue 12 Pages 965-970
Published: 2006
Released on J-STAGE: May 08, 2007
JOURNAL OPEN ACCESSCarbon nanotubes (CNT) have superior mechanical properties and high thermal conductivity. For such reasons, the development of CNT-metal matrix composite is gaining wide research attention. In this study, Al/CNT composite was fabricated by powder metallurgy employing the slurry mixing process and Spark Plasma Sintering (SPS) to overcome fabrication problems like agglomeration, which leads to the decrease in thermal conductivity and density.
Slurry precursors with homogeneously dispersed CNT were obtained by hetero-aggregation, with optimum amount of ethanol. By sintering these precursors, the composites densified up to more than 99% in relative density. Dispersion and orientation of CNTs were verified by FE-SEM observation of microstructure. The thermal conductivity of the composites decreased with increasing CNT content, and the corresponding thermal anisotropies are indicated. The thermal properties are improved by extending the holding time during sintering.View full abstractDownload PDF (1193K) -
Akinoiri Muto, Yuki Tohji, Thallada Bhaskar, Yusaku Sakata2006 Volume 53 Issue 12 Pages 971-977
Published: 2006
Released on J-STAGE: May 08, 2007
JOURNAL OPEN ACCESSThe ruthenium-porous carbon composites were prepared from a commercial chelate resin (IRC748) with the adsorption of aqueous ruthenium ion (Ru3+) by carbonization (N2) and activation (CO2) at 800°C. The specific surface area and pore volume of the composites depended on the amount of Ru3+ adsorbed on the chelate resin. The ruthenium ion changed to metallic ruthenium when the ruthenium content of the composite (XRu) was below 10 mass%. When XRu was above 36 mass%, not only metallic ruthenium but also ruthenium oxide (RuO2) were found in the composite. The crystalline size of the ruthenium compounds from the Scherre equation were almost 30-33 nm by XRD analysis. The ruthenium-porous carbon composites were applied to electrode of capacitor. The specific capacitances (CS) of the composite were stable in the charge and discharge experiment. The CS depended on XRu; when XRu was small (0-30 mass%), Cs deceased linearly with increasing XRu. However, CS increased with increasing XRu (> 30 mass%). The effect of ruthenium content on the capacitance was also discussed by comparing the experimental results of physical mixing of porous carbon and ruthenium oxide.View full abstractDownload PDF (612K)
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