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Volume 47, Issue 12
Displaying 1-14 of 14 articles from this issue
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Kiyokata Iizumi, Hiraomi Izumi, Takeshi Sasaki, Katsuya Kudaka2000 Volume 47 Issue 12 Pages 1247-1252
Published: December 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMC precursor powders were produced by ball-milling of Ti-C-B (2:1:2) mixed powders for various times of 10-40 h using a planetary ball mill at rotary speed of 290/650 rpm. TiC-TiB2 composites were produced by reactive hot-pressing of the MC precursors at 1400-2000°C. The hardness generally increases with densification and decreaes with the increase of crystallite size. The densification is enhanced by sintering temperature, heat of reaction and fineness of mixed powders produced by ball-milling. Maximum values of the relative density and the micro-Vicker's hardness of the composite were 97.5% and 25.5 GPa, respectively, for the milling time, 20h and the sintering temperature, 1900°C.View full abstractDownload PDF (3615K) -
Akihiro Matsumoto, Keizo Kobayashi, Toshiyuki Nishio, Kimihiro Ozaki, ...2000 Volume 47 Issue 12 Pages 1253-1257
Published: December 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSFe-35-50at%AI powder mixtures as starting materials of iron and aluminum elemental powders were milled in a planetary ball mill in argon atmosphere. The structure of powders milled for above 360ks may be FeAl intermetallics with B2 structure in disordered state. The powders were consolidated using pulse current sintering in vacuum at 1273 K. With increasing aluminum content, tensile strength of the compacts decreased linearly and the values were no less than those obtained in the previous studies. This result is attributed to a high degree of refinement of the microstructure for FeAI compacts prepared by pulse current sintering method of mechanically alloyed powders.View full abstractDownload PDF (4053K) -
[in Japanese]2000 Volume 47 Issue 12 Pages 1260
Published: December 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (105K) -
Hideshi Miura, Shinji Fujita, Masakazu Fujita, Ryuji Ninomiya2000 Volume 47 Issue 12 Pages 1261-1266
Published: December 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMetal injection molding(MIM)process is hoped to be one of processing for required to more complicated parts of magnetic components.
In this study, the effect of different types of powders(prealloyed and mixed elemental powders)on the magnetic properties of permalloy(Fe-50mass%Ni)through the MIM technique was investigated. Approximately 94% of theoretical density was obtained by using the prealloyed powder, and the retained carbon and oxygen contents were controlled to be low. On the other hand, 96% of theoretical density was obtained by using the mixed elemental powder, but the magnetic properties were inferior to that of prealloyed powder's because of high retaind oxygen content. By using the carbonyl Fe powder with high carbon, the retained oxygen and carbon content could be controlled to be low, resulting in the improved magnetic properties.View full abstractDownload PDF (6858K) -
Hideshi Miura, Kazuma Miyata, Akihito Otuka, Masakazu Achikita2000 Volume 47 Issue 12 Pages 1267-1271
Published: December 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSFe-Ni-C system low alloy steels have been developed to enhance the mechanical properties of Fe-Ni system which is a popular steel for Metal Injection Molding(MIM)process. Although the assessment of dynamic failure properties such as impact and fatigue strengths are important, there are few reports about the dynamic properties of injection molded Fe-Ni-C system low alloy steels at the present time.
In this study, the behavior of dynamic properties(impact and fatigue strengths)and carbon control by solvent debinding followed by thermal debinding for Fe-2%Ni-0.7%C low alloy steels produced by MIM process was investigated. Retained carbon contents was precisely controlled to 0.7 mass % by continuous process of thermal debinding and sintering. Dynamic properties of the injection molded steels were superior to those of the conventional P/M steels with the same composition, since the pore structure of the former was finer and more spheroidized as compared to that of the latter.View full abstractDownload PDF (5036K) -
Hideki Nakayama, Hideki Kyogoku, Shinichiro Komatsu2000 Volume 47 Issue 12 Pages 1272-1276
Published: December 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe effects of powder characteristics on the microstructures and mechanical properties of sintered alloy tool steel (SKD11) compacts by metal injection molding were investigated. A gas-atomized(GA)and a water-atomized(WA)alloy tool steel powders and a polyamide binder were used. They were mixed well and injected into metallic molds for transverse test specimens. These injection-molded specimens were debound at 593 K in air and then were sintered at various temperatures between 1473 K and 1483 K in vacuum. These sintered compacts were heated at 1293 K and quenched, and then were tempered at various temperatures between 453 K and 803 K. The densification of the GA powder compact was fairly superior to that of the WA powder compacts. Consequently, the mechanical properties of the sintered GA powder compacts were superior to those of the sintered WA powder compacts. The mechanical properties equivalent to those of the wrought alloy tool steel could be fabricated successfully by controlling the sintering and heat-treatment conditions precisely.View full abstractDownload PDF (8203K) -
Kiyotaka Kato, Takami Masui2000 Volume 47 Issue 12 Pages 1277-1282
Published: December 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe sintered compacts of Ni3Al intermetallic compounds(Ni-25Al, Ni-24Al and Ni-23Al(at.%))with high density (more than 96%) could be obtained by powder injection molding(PIM)process, using Ni and NiAl(Ni-50Al)powders as the starting materials. The debound compacts were sintered at 1325 °C for 2 hours in vacuum(10-2Pa order). The structures were single phase of γ' in the Ni-25Al and Ni-24Al compacts, while that was two phases of γ' and a small amount of γ in the Ni-23Al compact. Tensile tests were performed in air at room temperature, 200°C, 400°C, 600°C and 800°C. The resuls of tensile tests were summarized as follows.
(1) At room temperature, the yield stresses for all compacts were a little over 400MPa. On the other hand, both elongation to fracture and tensile strength increased with increasing Ni content. The most Ni-rich compact Ni-23Al showed the good tensile properties of 13% elongation and 850 MPa tensile strengh.
(2) The yield stresses for all compacts increased with increasing temperature up to 400°C. However, the elongations of them decreased at over 400°C. They all fractured in elastic regions at 600°C.View full abstractDownload PDF (7604K) -
Syuntaro Terauchi, Tsuneo Teraoka, Takashi Shinkuma, Takashi Sugimoto2000 Volume 47 Issue 12 Pages 1283-1287
Published: December 15, 2000
Released on J-STAGE: July 12, 2010
JOURNAL FREE ACCESSSince a TiAl-type intermetallic compound (TiAl) has an excellent high temperature strength and corrosion resistance, in addition to light weight, it is expected to be applicable to the engine parts. However, it is difficult for TiAl to produce a part with a complex shape, and considerable cost will be required. In this study, it was tried to develop a technology for producing TiAl products with high density and high efficiency by using metal powder injection molding (MIM) process. Several kinds of TiAl alloy powders made by the self-propagating high temperature synthesis process were mixed with an organic binder, kneaded and then injection-molded into tensile specimens. These compacts were subjected to the treatment for removing the binder and sintering, resulted in a relative density as high as 97%. By room and high temperature tensile tests, it was found that, Ti-47.4Al-2.6Cr (at%) has the strength and ductility as those of the conventional processed materials.View full abstractDownload PDF (5871K) -
[in Japanese]2000 Volume 47 Issue 12 Pages 1290
Published: December 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (110K) -
Yoshimoto Wanibe, Takashi Itoh2000 Volume 47 Issue 12 Pages 1291-1299
Published: December 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSQuantitative consideration is essential to engineering fundamentals of powder technologies. Systematic investigations have been being experimentally studied by helps of characterization of discrete phases and simulations of processing. There follows the application of such quantitative consideration for practical problems, which can result in significant findings which are over and above what can be conventionally obtained. It is presented here what can be achieved up to now by the new quantitative approach to powder technology.View full abstractDownload PDF (663K) -
Keijiro Terashita, Susumu Natsuyama, Takehiko Nishimura, Hiromitsu Koj ...2000 Volume 47 Issue 12 Pages 1300-1305
Published: December 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSAgitating granulation method has been widely used. However, particle motion in an agitation granulator is not obvious. It is useful in a reasonable process analysis to know the particle motion in the granulator.
In the present study, three-dimensional motion of individual particles in an agitation granulator with a three-blade was analyzed using simulation by discrete element method (DEM). The effect of the rotation speed of agitating blade on particle behavior was numerically simulated and the elastic energy of spring in the model of contact force was calculated. Furthermore, the experiment in agitating granulation was conducted by changing rotation speed of agitating blade and the results of simulation were compared to those of granulation experiment. These results have showed that the DEM simulation could provide useful explanations on particle behavior and granulation process in an agitation granulator.View full abstractDownload PDF (2860K) -
Keijiro Terashita, Susumu Natsuyama, Takehiko Nishimura, Hiroshi Sakam ...2000 Volume 47 Issue 12 Pages 1306-1311
Published: December 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSNumerical simulations for equipment design were carried out using the discrete element method (DEM). A new coater (Small-particle Coater) for use in coating of small particles has been developed. This coater has been improved in comparison with Wurster equipment by conically expanding the lower part of the draft tube of the Wurster and providing a side air jetting mechanism. Particle behavior in Small-particle Coater was numerically simulated and compared with that in the Wurster. The result showed that particle stagnant zones outside the draft tube in the coater decreased as compared with the Wurster. The Small-particle Coater was actually produced, for experimental coating of small particles and comparison of the coating by the Small-particle Coater with that the Wurster. The result confirmed that the Small-particle Coater designed on the basis of simulation results was useful for coating of small particles.View full abstractDownload PDF (2917K) -
Susumu Shima, Hidetoshi Kotera, Yasushi Yamamoto2000 Volume 47 Issue 12 Pages 1312-1317
Published: December 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSSimulation of die-compaction of an axi-symmetric multi-stepped part of an iron powder is performed. The shape of the compact is like a synchronizer hub; hub and rim portions are of different height, and therefore compression ratio of the rim portion to that of the hub gives a great influence on density distribution and occurrence of slip-crack. Thus, the effects of tool kinematics on occurrence of a slip-crack like defect and density variation in compact are investigated. It is shown that there is a critical compression ratio in the rim portion relative to that in the hub above which a slip-crack like defect occurs and that the critical ratio increases with increasing friction at the powder-tool interfaces. It is also shown that there is an optimum compression ratio at which the density variation gives a minimum and that this ratio again increases with increasing the friction. Based on these results, we propose an optimum tool kinematics that gives desired dimensions and a desired mean density ratio for this multi-stepped part.View full abstractDownload PDF (545K) -
Naoki Matsuoka, Koji Hayashi2000 Volume 47 Issue 12 Pages 1318-1327
Published: December 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThis paper reviews our simulation study by numerical calculation based on two-, three- and multi-grain-size models on WC grain growth in fine grained WC-Co hardmetal doped with VC. The study aimed to presume or predict the following: (1) the cause and conditions for the abnormal grain growth which occurs in some cases in the fine grained hardmetal prepared from fine WC powders with mean grain size below about 0.2μm, and (2) how the mean grain size of the hardmetal varies with decreasing mean grain size of the WC starting powder to 0.1 μm or nano-meter size. The calculation results by these three kinds of models suggested the following, respectively: (1) the occurrence of the abnormal grain growth is generally substantial for WC starting powder with bimodal size-distribution and mean grain size below 0.1-0.2μm, and not due to the non-uniform distribution of the grain growth inhibitor, (2) the introduction of middle grains caused the disappearance of small (fine) grains during sintering, leading to abruptly increase of the mean grain size of alloy, and (3) the mean grain size of alloy becomes so large as about 0.3-0.4μm, even when the WC starting powders with nano-size as well as 0.1μm are used.View full abstractDownload PDF (2887K)
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