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Volume 55, Issue 12
December
Displaying 1-8 of 8 articles from this issue
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Paper
Paper
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Atsushi Hibino, Hiroshi Iwatsubo, Hidekazu Kawajiri2008 Volume 55 Issue 12 Pages 813-822
Published: 2008
Released on J-STAGE: January 21, 2009
JOURNAL OPEN ACCESSIn recent years, the magnesium alloy is frequently used for automobile components, computer parts and digital camera parts. However, a lot of magnesium chips from the manufacturing process are dumped as the industrial waste, because the surface area per unit volume is wide and the magnesium machine chips are easy oxidized during the melting process. However, the magnesium chips will be able to be recycled by the compaction forming to avoid the oxidation. In the paper, the compaction forming experiments of the magnesium machine chips are attempted by mixing of Mg chips, Al chips and aluminum melting flux such as NaCl, MgCl2. For the compacts obtained, the check of crack, the strength test and the microstructure observation of the compact are performed. Furthermore, the formed compact was melted in molten aluminum. And, the mechanical strength of the obtained Al-Mg alloy is compared with that of the commercial alloy.View full abstractDownload PDF (2130K) -
Tadahiro Wada2008 Volume 55 Issue 12 Pages 823-826
Published: 2008
Released on J-STAGE: January 21, 2009
JOURNAL OPEN ACCESSThe tool life in cutting sintered steel is shorter than that in cutting melted steel, such as carbon steel. In order to determine an effective coating film for cutting sintered steel with a coated cemented carbide tool, tool wear was experimentally investigated. The work materials used were hardened sintered steel and sintered stainless steel. Two kinds of sintered steels were turned with four kinds of physical vapor deposition (PVD) coated cemented carbide tools. The coating films used were TiN coating film, (Ti, Al)N coating film and (Ti, W, Si)N coating film.
The following results were obtained: (1) In cutting two kinds of sintered steel, namely hardened sintered steel and stainless sintered steel, the wear progress of (Ti, W, Si)N coated cemented carbide tool was the slowest. (2) The main wear mechanism of three coated cemented carbide tools was the abrasive wear.View full abstractDownload PDF (738K) -
Hayato Hishinuma, Kenji Kamishima, Koichi Kakizaki, Nobuyuki Hiratsuka2008 Volume 55 Issue 12 Pages 827-830
Published: 2008
Released on J-STAGE: January 21, 2009
JOURNAL OPEN ACCESSSr2FeMo1-xNbxO6 (x=0, 0.2, 0.4, 0.6, 0.8 and 1.0) samples were prepared by a conventional ceramic method. The samples were sintered in 3 %H2/N2 gas at 1100°C for 6 hours. Analysis of the X-ray data shows that the samples are of single phase in double perovskite. The magnetization and the conductivity values are found to decrease with increasing x. Whereas, the Seebeck coefficient is found to increase with respect to x in all compounds.View full abstractDownload PDF (455K) -
Toshiyuki Tanaka, Masaru Tada, Takashi Nakagawa, Yutaka Tamaura, Masan ...2008 Volume 55 Issue 12 Pages 831-835
Published: 2008
Released on J-STAGE: January 21, 2009
JOURNAL OPEN ACCESSAqueous growth mechanism of ferrite (intermediate between Fe3O4 and γ-Fe2O3) nanoparticles via the precipitation and oxidation of green rust was studied by monitoring pH and ORP of the reaction solution. While Fe3O4 was growing, both pH and ORP reached plateaus of pH=6 ∼ 7 and ORP=−400 ∼ −300 mV. The pH was kept constant because the formation of Fe3O4 from green rust is expressed by the formula [FeII2FeIII1(OH)6]+ · [Cl1 · mH2O]−+NO3−→Fe3O4+(3+m)H2O+Cl−+NO2↑ where H+ is not released. The observed value of ORP was ascribed to the interfacial potential between Fe3O4 and FeOH+, a dissolved species from the green rust. After ending the growth by exhausting the green rust, the surface of Fe3O4 was oxidized to γ-Fe2O3, which gave the final values of pH=4 ∼ 5 and ORP ≈ 0 mV. Adding sucrose, a disaccharide, to the reaction solution decreased the growth rate of the ferrite particles. This supported our proposal that a disaccharide suppresses the growth of each crystal plane and thus enables the particles to grow spherical in shape.View full abstractDownload PDF (843K) -
Yukihiro Hosoda, Satoshi Sunada, Tsutomu Yamamoto, Kazuhiko Majima2008 Volume 55 Issue 12 Pages 836-841
Published: 2008
Released on J-STAGE: January 21, 2009
JOURNAL OPEN ACCESSThough WC-Co cemented carbides are widely used for a variety of machining, drilling, metallic mold and other applications because of their high strength, high hardness and excellent wear resistance, their poor corrosion resistance in aqueous solutions reduces the scope of their application. In this experiment, three kinds of WC-Cr3C2-Co cemented carbides were used, and the influence of Co content on corrosion characteristics of them was investigated by the electrochemical methods such as the potenitodynamic polarization test and electrochemical impedance spectroscopy (EIS), and the observation by scanning electron microscopy (SEM). All of the three specimens showed the similar active, passive and over passive regions during the polarization test, though the passivation was retarded with increasing amount of Co content. EIS test indicated that all of the three samples had the similar capacitance semicircle in the first quadrant. After that, the second capacitance semicircle which involve a film formation following the first capacitance semicircle and the induction semicircle following the second capacitance semicircle were confirmed. From this EIS test result, it was confirmed that the charge transfer resistance (Rct) decreased with an increase in Co content.View full abstractDownload PDF (1285K)
Special Issue:Synthesis of New Materials by Mechanicals by Mechanical Alloying
Summarization
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Keiichi N. Ishihara2008 Volume 55 Issue 12 Pages 844
Published: 2008
Released on J-STAGE: January 21, 2009
JOURNAL OPEN ACCESSDownload PDF (130K)
Paper
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Hiroyuki Nakayama, Keizo Kobayashi, Masashi Mikami2008 Volume 55 Issue 12 Pages 845-849
Published: 2008
Released on J-STAGE: January 21, 2009
JOURNAL OPEN ACCESSThe Fe2VAl alloy was produced through the mechanical alloying and the pulsed current sintering process to clarify the optimum milling condition for obtaining homogeneous Fe-Al based intermetallic compounds. The homogeneity of the milled powder was evaluated from the absolute value of Seebeck coefficient, |S|, of the thermoelectric Fe2VAl alloy. It used to be that the synthesis of the homogeneous Fe2VAl powder yields after the milling for 720 ks in the case of using conventional planetary ball milling process. On the contrary, under the modified milling conditions optimized in this study, which were the orbital speed of 900 rpm and the inversed rotating speed of 300 rpm, enabled to cut down the milling time can be shortened to 10.8 ks to provide the satisfactory Fe2VAl powder. The |S| values of Fe2VAl alloy sintered from the powder produced through the optimum milling were comparable to those of alloys fabricated by a conventional melting technique.View full abstractDownload PDF (884K)
Rapid Communication
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Yoshimi Murata, Emi Shindou, Akira Yoshida, Eiji Yuasa2008 Volume 55 Issue 12 Pages 850-854
Published: 2008
Released on J-STAGE: January 21, 2009
JOURNAL OPEN ACCESSIn the purpose of recycling of the magnesium alloy, powder mixture of AZ31 machined chips and boron powder, which was added boron contents as Mg/B=1/2 molar ratio, was mechanically alloyed for various milling times using planetary ball mill, for preparation of magnesium diboride (MgB2). The phases formed by the mechanical alloying in the powder were investigated by X-ray diffraction analysis. The MgB2 phase generates in the mechanically alloyed powder when the powder mixture was milled for a long time more than 72ks. And then, when the mechanically alloyed powder was heat-treated at 723K∼873K for 3.6ks, the MgB2 phase grows up. When the mechanically alloyed powder was hot-pressed at various temperatures by compressing pressure of 200MPa, densely compacts was obtained at over 673K and the hardness and the rupture strength of the compacts increase with increasing of compacting temperature.View full abstractDownload PDF (915K)
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