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Volume 52, Issue 6
June
Displaying 1-13 of 13 articles from this issue
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Paper
Paper
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Tadahiro Wada, Kazuki Hiro2005 Volume 52 Issue 6 Pages 399-403
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSThe tool life in turning of Inconel 718 becomes shorter than that in turning of carbon steel. In order to clarify an effective tool material for the cutting of Inconel 718, the tool wear and the surface roughness were experimentally investigated. The Inconel 718 was turned with WC-Co cemented carbide tool and WC-Ni cemented carbide tool. The main results obtained are as follows: (1) In the WC-Co cemented carbide tools, the wear progress of WC-7%Co cemented carbide tool was slowest. (2) The wear progress of WC-7%Ni cemented carbide tool was slower than that of WC-7%Co cemented carbide tool. (3) In the WC-Ni cemented carbide tools, the wear progress of WC-7%Ni cemented carbide tool was slowest.View full abstractDownload PDF (1187K) -
Mitsutoshi Kamakura, Hideaki Shibata, Katsuhiro Nishiyama, Keiro Tokaj ...2005 Volume 52 Issue 6 Pages 404-410
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSIn order to improve the mechanical properties of functional Mg alloys, the forming process was investigated using Mg powder mixed with Zr powder. Fine and coarse Mg and Zr powders were used and Zr content was varied from 1 mass% to 20 mass%. Milling time was 7.2 ks and the mixed powders were pressed at a temperature of 573 K and then extruded at an extrusion ratio of 30 at the same temperature. The mechanical properties of the hot-extruded alloys were examined and the effects of powder size and Zr content were discussed. In the hot-extruded Mg-Zr alloys using fine Mg and Zr powders, Zr particles were dispersed uniformly within its microstructure. It was found that the mechanical properties such as Vickers hardness, Young's modulus, bending strength and internal friction increased significantly with increasing Zr content, compared with the hot-extruded Mg material and the hot-extruded Mg-Zr alloys using coarse Mg and Zr powders. Furthermore, such mechanical properties of the hot-extruded Mg-Zr alloys using fine Mg and Zr powders were improved considerably compared with AZ31 wrought alloy, AZ91 casting alloy and the damping casting alloys such as MCM and K1A. Therefore, it was confirmed that the hot-extruded Mg-Zr alloys fabricated in this study has a potential as a structural and functional Mg alloy.View full abstractDownload PDF (1708K) -
Nobuyoshi Takabatake, Shizuo Nakamura, Kentaro Ohhashi2005 Volume 52 Issue 6 Pages 411-415
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSLaminated TiO2/Fe2O3/ITO and TiO2/Fe2O3/glass films acting under visible light irradiation were prepared by sol-gel processing as well as TiO2/V2O5/ITO or TiO2/WO3/ITO films. Under Xenon lamp irradiation, the rate of bleaching of Methylene Blue (M.B.) on TiO2/Fe2O3/ITO or TiO2/WO3/ITO was found to become greater than that of the original TiO2/glass which was the best under black light irradiation. The TiO2/Fe2O3/glass, whose Fe2O3 was confirmed to be formed as α-hematite by using Mossbauer measurement, seems to be applicable because of its photocatalytic ability.View full abstractDownload PDF (654K) -
Hideki Oginuma, Ayako Ohguchi, Sayaka Ohno, Eiji Yuasa, Yoshinari Oki2005 Volume 52 Issue 6 Pages 416-422
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSAn aluminum and a zinc powder were mixed to machined chips of AZ31 alloy with various contents, and then the powder mixtures were mechanically alloyed for various milling times using planetary ball mill, for the purpose of recycling of the magnesium alloy. Crystal phase formed in the obtained powder were investigated by X-ray diffraction and Vickers hardness of the powder particles to confirm the formed phases. When Mg-Al system powder mixture was milled for 72 ks by the planetary ball mill, super-saturated solid solution α-Mg and intermetallic compound Mg17Al12 phase are formed, while by milling using the oscillatory ball mill 54 ks was necessary. In the case of mechanically alloyed Mg-2.5 mol% Zn powder, super-saturated α-Mg phase with 2.5 mol% Zn concentration forms. The structures of Mg-28 and 52 mol% Zn powder obtained by the mechanical alloying consist of Mg2Zn2 or MgZn2 and Mg7Zn3 phases and then these phases became amorphous by milling for further time. In the case of mechanical alloying for ternary Mg-Al-Zn system, an icosahedron Mg49(Al,Zn)32 phase, the quasi crystal, forms by the milling for 72 ks in the composition range as following; (30-50)mol% Mg with Al/Zn=(90/10-60/40) molar ratio, Mg-(30-50)mol% Al-20 mol% Zn and Mg-(10-30)mol% Al-40 mol% Zn.View full abstractDownload PDF (873K)
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Shoichi Nasu, Shinji Nagata, Katsumi Takahiro, Kiichiro Yoshii, Kentar ...2005 Volume 52 Issue 6 Pages 423-426
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSWe examined the compatibility of lithium titanite (Li2TiO3, tritium breeding materials) fused crystals with nickel (Ni) foils by Rutherford backscattering spectroscopy (RBS) after heat-treatments at 673 K, 773 K and 873 K for 600 min in vacuum (10-6 Pa). An inter diffusion of Ni and titanium (Ti) atoms at 773 K followed a diffusion of a small amount of Ni atoms into the surface of Li2TiO3 at 673 K. At 873 K, Ti and oxygen (O) atoms reached the front surface of the Ni foil and Ni atoms migrated into the Li2TiO3 crystal. In addition, we estimated the diffusion constants at 873 K for Ti and O in Ni.View full abstractDownload PDF (2241K) -
—The Effect of Passivation Films—Shoichi Nasu, Shinji Nagata, Kiichiro Yoshii, Katsumi Takahiro, Naoto ...2005 Volume 52 Issue 6 Pages 427-429
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSWe examined compatibility of sputtered tungsten (W) films with lithium oxide (Li2O, tritium breeding materials) single crystals, the surface of which were passivated by aluminum (Al), silicon (Si) or titanium (Ti) by Rutherford backscattering spectroscopy (RBS). Initial small chemical reactions were observed after heating at 573 K for 1 min in vacuum of 10-6 Pa for each sample. After further heat treatments from 573 K to 723 K there was no additional drastic diffusion.View full abstractDownload PDF (1703K)
Special Issue: Net Shaping and Near Net Shaping of Powder Compaction
Summarization
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Hiroki Miyamoto2005 Volume 52 Issue 6 Pages 432
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSDownload PDF (92K)
Paper
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Keizo Kobayashi, Akihiro Matsumoto, Kimihiro Ozaki, Toshiyuki Nishio, ...2005 Volume 52 Issue 6 Pages 433-436
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSTi-20 mass% Ni cermet was near net formed by pulsed current sintering at low temperature. When TiC powder and Ni powder as starting materials were mechanically alloyed for 72 ks, Ni was homogeneously distributed. The obtained mixture was consolidated by a pulsed current sintering using by graphite die and punch. At the heating rate of 100 K/min, the liquid phase of Ni was generated because of the overheating of the punch. The generation of the liquid phase promoted the reaction with the graphite punch and obstructed the densification of a compact. It was effective to increase the ratio of the sectional area of punch to that of die to prevent this phenomenon.
When 37.5 mass% of the TiC powder in the MA was changed into the Ti powder and C powder, a combustion reaction was observed during the pulsed current sintering. This reaction was efficient for the pulsed current sintering to near net forming of TiC-20mass%Ni at a low temperature.View full abstractDownload PDF (1134K) -
Hisataka Toyoshima, Tokihiro Shimura, Atsushi Watanabe, Hidenori Otsu2005 Volume 52 Issue 6 Pages 437-441
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSWe developed the mass production process of 2%Ni-Fe pre-alloyed powder by high-pressure water atomization. When the 2%Ni-Fe pre-alloyed powder was sintered, the sintering characteristics were equal to that of pre-mixed powder of the carbonyl iron and carbonyl nickel, which are conventionally used in powder metallurgy industry. The sintering speed increased as the particle size became finer, so the higher sintering density was obtained even if the sintering temperature was the same. Environmental/sanitary problems and chemical segregation problem, which are inherent in using pre-mixed carbonyl powders, will be solved by adopting the pre-alloyed powder for the production of MIM parts. As a result, it can be expected that the MIM market will be much more expanded.View full abstractDownload PDF (1570K)
Review
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Fujio Tsumori2005 Volume 52 Issue 6 Pages 442-445
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSA new powder compaction process named “Bingham semi-solid/fluid Isostatic Pressing (BIP)” is proposed and developed to fabricate green compact with complicated shapes. Conventional processes such as die pressing or CIP (cold isostatic pressing) process, are encountered two technical problems: inhomogeneous density distribution in powder compact and breakage of products during unloading process. The present process, where a semi-solid mold works also as a pressurizing medium, can overcome such problems. Yield stress of the mold is much lower than process pressure for BIP, so that the mold behaves like a liquid that applies isostatic pressure to the powder. This behavior of the fluid mold prevents the damage of powder compact during the unloading process. Finally, it is demonstrated that complicated powder compacts are fabricated by this process.View full abstractDownload PDF (913K)
Paper
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Janghwan Oh, Atsushi Kakitsuji2005 Volume 52 Issue 6 Pages 446-452
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSA new isostatic pressing method named “Bingham semi-solid/fluid Isostatic Pressing (BIP)” has been developed in which Bignham semi-solid/fluid material is employed as a mold material to form a green body with complicated shape without the crack due to the spring-back of a rubber mold. In this paper, a few parameters of BIP process that influence the dimensional accuracy of a green body were investigated.
The soaking with wax to the green body associated with applied pressure, powder size and the ratio of mold thickness-to-width was examined. Mixing the powders with different diameter and increasing the packing density could prevent the soaking. To get the green body with desired shape, the relation between the thickness of a mold and the dimensional accuracy was investigated. Granulated powder and non-granulated powder were compared to investigate their effect on the dimensional accuracy of a green body. Granulated powder was more effective than non-granulated powder.View full abstractDownload PDF (2172K) -
Fujio Tsumori, Yasuhiro Hara, Ryota Yasutomi, Susumu Shima2005 Volume 52 Issue 6 Pages 453-457
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSIt is extremely difficult to fabricate thin plate parts by conventional powder metallurgy processes using dry powder; uni-axial pressing results in inhomogeneous density distribution, which causes distortion or breakage of sintered products; isostatic pressing, which could make compacts with homogeneous density distribution, also encounters serious problems such as breakage due to tensile stress at the surface of powder compacts by rubber mold during unloading process. In this study, newly developed Bingham Semi-solid/fluid Isostatic Pressing (BIP) process is employed to overcome these problems. For demonstration, an attempt is made to fabricate simple disks and wavy sheets with about some hundreds micrometer thickness. We also develop and perform an FEM simulation to investigate deformation patterns and density distribution in powder compact during the process, and compare with experimental results.View full abstractDownload PDF (1338K) -
Fujio Tsumori, Fumikazu Kurihara, Hidetoshi Kotera, Susumu Shima2005 Volume 52 Issue 6 Pages 458-463
Published: 2005
Released on J-STAGE: April 28, 2006
JOURNAL OPEN ACCESSNd-Fe-B magnet, which possesses the highest magnetic performance, is fabricated by powder metallurgy process. The magnetic powder is compacted under an applied magnetic field for the particles' easy directions of magnetization to be oriented along the magnetic flux. It is widely known that the magnetic powder flows and moves during this process both by the applied magnetic field and by the applied pressure. Since this process determines the final properties of the magnet, it is of great importance to clarify the behavior of the powder during the process.
In the present study, we focus on the flow behavior of Nd-Fe-B powder due to an applied magnetic field. An attempt is made to make clear the powder flow by in-situ observation with a transparent die set. An FEM-DEM simulation is also performed to investigate the flow of magnetic flux that affects the movement of the powder. It is thereby shown that simulated results of the flow of magnetic powder and change of the structure built-up by particles are in good agreement with experimentally derived ones.View full abstractDownload PDF (1882K)
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