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Volume 51, Issue 5
Displaying 1-11 of 11 articles from this issue
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Norimitsu Hirose, Shin-ichi Tanaka, Toshiyuki Tanaki, Junichi Asami2004 Volume 51 Issue 5 Pages 315-322
Published: May 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe relationship between the elastic modulus and porosity of sintered Fe-Cu compacts was investigated by an acoustic pulse method.
Young's and shear moduli of sintered Fe compacts and sintered Fe-Cu compacts decreased with the increasing porosity, and depended on the pore shape. The pore shape became complicated when sintering at lower temperature or for the sintered Fe-Cu compact. The complicate shaped pores decreased the Young's modulus more than the shear modulus, and then Poisson's ratio decreased. Poisson's ratio is also affected by the pore connectivity, open or closed pores, because the decreasing trend of Poisson's ratio versus the porosity of sintered compact with open and closed pores differed from that with almost open pores. The porosity, at which the closed pores change to almost open pores, in this study, was approximately 20% regardless of the type of Fe and Cu powders, Cu contents and sintering temperatures. When considering the discontinuity of elasticity versus porosity, the Young's and shear moduli and the Poisson's ratio calculated by fitting each equation against porosity, which have been derived from the sintered Fe compact, corresponded to each measured value of the sintered Fe-Cu compact.View full abstractDownload PDF (4242K) -
Mitsutoshi Kamakura, Hideaki Shibata, Katsuhiro Nishiyama, Keiro Tokaj ...2004 Volume 51 Issue 5 Pages 323-329
Published: May 15, 2004
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSIn order to improve the strength of the functional MCM (Mg-Cu-Mn) casting alloy that has been developed as one of damping Mg alloys, the powder extrusion process was applied and the effect of Zr addition was studied using MCM alloy powder mixed with Zr powder. For the powder hot-extruded alloys produced, microstructure characterization was performed using optical microscope and the mechanical properties such as Vickers hardness and bending strength were evaluated. Young's modulus and internal friction were also measured with the free resonance frequency technique. It was found that grain size increased with increasing extrusion temperature and grain size refinement was recognized to occur around Zr particles dispersed in the matrix. Vickers hardness was nearly similar to, or slightly lower than, that of the conventional casting alloys such as AZ91 and AM60, while bending strength and Young's modulus were improved remarkably compared with those casting alloys. The internal friction was the same as that of the conventional damping alloys. Based on the above experimental results, it was concluded that the high performance of the functional MCM alloy could be achieved with the powder extrusion process.View full abstractDownload PDF (4346K) -
Tadahiro Wada, Junsuke Fujiwara, Shinsaku Hanasaki2004 Volume 51 Issue 5 Pages 330-335
Published: May 15, 2004
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe tool life in turning of the sintered steels becomes shorter than that in turning of the melted steels such as carbon steels. In order to clarify an effective tool material for the high speed turning of the forged sintered material, the tool wear was experimentally investigated. The forged sintered material was turned with various tool materials at the cutting speed 5 m/s, the feed rate 0.2 mm/rev and the depth of cut 0.1mm. The main results obtained are as follows: (1) The abrasive wear was remarkably found on the worn surface of the coating layer in all PVD coated cemented carbide tools. (2) The wear progress of Ti75V25N PVD coated tool was slowest, because the Ti75V25N coating layer had high micro Vickers hardness and high critical load measured by the scratch test. (3) In the Al2O2-TiC ceramics tool, the tool wear decreased with the increase of the TiC contents. The wear progress of the 30%Al2O3-70%TiC ceramics tool was slowest among four ceramics tools. However, the wear progress of the 30%Al2O3-70%TiC ceramics tool was faster than that of the Ti75V25N PVD coated tool. The wear progress of both Al2O3 ceramics tool and Si3N4 ceramics tool was rapid.View full abstractDownload PDF (6945K) -
Masafumi Kobune, Shinichi Kojima, Yusuke Nishioka, Tetsuo Yazawa2004 Volume 51 Issue 5 Pages 336-340
Published: May 15, 2004
Released on J-STAGE: July 12, 2010
JOURNAL OPEN ACCESSFerroelectric properties and memory characteristics of Pt/0.24Pb(Zn1/3Nb2/3)O3⋅0.384PbZrO3⋅0.376PbTiO3 (PZNZT)/PbTiO3/Pt capacitors fabricated by crystallizing amorphous PZNZT films at 500°C for 1 h under high pressures of 1.0-176.5 MPa using hot isostatic pressing (HIP) are investigated. The relative permittivity decreased linearly with increasing HIP pressure. All the samples treated at pressures greater than 17.7 MPa completely showed fatigue-free characteristics even after up to 3×1010 cycles. From dielectric measurements and cross-sectional highresolution TEM images, these fatigue-free behaviors may be caused by that several elongated amorphous areas oriented parallel to the substrate formed near the interface between the crystallized PZNZT layer and the PbTiO3 (PT) seed layer, which would play an important role in restraining the diffusion of lead from the crystallized layer toward the PT seed layer.View full abstractDownload PDF (1984K) -
Yasunobu Ogata2004 Volume 51 Issue 5 Pages 341-345
Published: May 15, 2004
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSEffects of dispersing fine milled powder in slurry on the degree of the crystallographic orientation of anisotropic ferrite magnets were investigated. A new process in which slurry of high solid concentration is kneaded was introduced. It was found that the kneading process is effective to improve the degree of the crystallographic orientation and magnetic properties of anisotropic ferrite magnets.
Sr ferrite magnets with Br=430 mT (4300 G) and iHc=318 kA/m (4000 Oe) were obtained by combining the kneading process and decreasing the average particle size of fine milled powder.View full abstractDownload PDF (341K) -
Akira Kishimoto, Yoshimitsu Numata2004 Volume 51 Issue 5 Pages 346-349
Published: May 15, 2004
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSα-silicon carbide ceramics with different nitrogen content were fabricated by changing the post-HIP nitrogen gas pressure. Resultant silicon carbide ceramics were all n-type semiconductors in which doped nitrogen played a role of donor. With the doping pressure up to 150MPa, incorporated nitrogen were dissolved into silicon carbide. Lattice parameter, carrier concentration and piezoresistance coefficient changed in accordance with the solution content. Over 150MPa, nitrogen incorporation continued to increase while nitrogen solution was saturated.View full abstractDownload PDF (331K) -
Mitsuru Nakamura, Hiromi Takahashi, Yoshimi Sugaya2004 Volume 51 Issue 5 Pages 350-355
Published: May 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSTo study rapid sintering by induction heating, we used high strength-alloyed steel powder, completely alloyed powder of 0.55 mass%Ni-0.6mass%Mo-0.2mass%Mn-0.5mass%C-bal.Fe. In this rapid sintering, evolution of a Martensitic or Bainitic structure in the matrix was examined to play a very important role. Thus, the substantial controlling factors were the holding time and cooling time for grain boundary diffusion. Experimental results showed that this process required a higher sintering temperature compared with the continuous furnace, but the sintered materials gained a higher radial crushing strength (R.C.S) by changing the holding time and cooling time. Although, the holding time were only 3-4minutes in the present process, and high strength-alloyed steel was also obtained to a very good size accuracy when putting it in practical use industrially. The optimum condition appeared to be a sintering temperature of 1573 K and holding time 120-180s with a heating time of 65s; the RCS data was attained about 1200 MPa.View full abstractDownload PDF (6086K) -
[in Japanese]2004 Volume 51 Issue 5 Pages 358
Published: May 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (110K) -
Yuji Yamasaki, Mari Nishi, Ken-ichi Takagi2004 Volume 51 Issue 5 Pages 359-367
Published: May 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSReaction boronizing sintering technique has successfully brought a development of Mo2NiB2 complex boride base cermets. The Mo2NiB2 boride base cermet consists of M3B2 type complex boride as a hard phase and a Ni base binder. Accrding to the previous investigation, it had been clarified that the additions of Cr and V to the cermet changed the boride phase structure from orthorhombic to tetragonal and resulted in a remarkable improvement of mechanical properties such as transverses rupture strength (TRS) and hardness associated with microstructural refinement. In this investigation, the effects of Mn on the mechanical properties and microstructure of the cermets were studied by using model cermets with composition of Ni-5mass%B-58.6 mass%Mo and Ni-4.5mass%B-47.9 mass%Mo-12.5 mass% V with five levels of Mn content from 0 to 10mass%. Appearance of significant microstructural refinement by an addition of Mn, especially suppression of grain growth of the boride resulted in the improvement of strength and hardness. The maxmum TRS obtained at 2.5mass%Mn of V added cermet were 3.5 GPa with hardness of 87 HRA.View full abstractDownload PDF (8420K) -
Kusuhiko Sakagami, Shinichi Kouno, Tsutomu Yamamoto2004 Volume 51 Issue 5 Pages 368-373
Published: May 15, 2004
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe bending and compressive fatigue characteristics of the normal sintered and HIP-treated WC-1 mass%Cr3C2-12mass%Ni alloy (Ni alloy) applied for non-magnetic or corrosion-resistant tools were mainly investigated and compared with those of WC-1 mass%Cr3C2-12mass%Co alloy (Co alloy) which was previously reported by us.
The results obtained were as follows. :1) The bending fatigue life was more superior in the HIP-treated Ni alloy than the normal sintered Ni alloy especially in the range of high applied stress. But the difference between them became smaller with decreasing the applied stress, and it was inclined to reverse around fatigue limit. 2) The bending fatigue life of HIP-treated Ni alloy lowered as compared with that of the HIP-treated Co alloy. 3) All the fracture origins of HIP-treated Ni alloy in the bending fatigue were Ni pools and the fracture form of the origin under the high applied stress showed a dimple pattern. The area of the dimple pattern decreased with decreasing the applied stress and conversely that of the brittleness fracture form increased, but it did not show a step-shaped form which was clearly observed in Co alloy. 4) The compressive fatigue life of the Ni alloy lowered remarkably as compared with that of the Co alloy. This result was considered to correspond to the fact that the plastic deformation was larger in Ni alloy than Co alloy.View full abstractDownload PDF (5547K) -
Yutaka Yanaba, Toshiyuki Takahashi, Koji Hayashi2004 Volume 51 Issue 5 Pages 374-384
Published: May 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSTiC-core/(Ti, Mo)C-rim structure in TiC-Mo2C-Ni cermet where the equilibrium phase of carbide is only (Ti, Mo)C is known to be not generated by solid-diffusion process, but by solution-reprecipitation process in the case of usual sintering temperatures (1528-1723 K). On the other hand, in our recent study on the microstructure of Fe-66.7at%Si peritectoid alloy where the equilibrium phase is FeSi2, it was found that FeSi-core in FeSi-core/FeSi2-rim structure hardly disappeared by solid-diffusion process in the compact inside, but relatively easily disappeared and/or shrunk near the compact surface to the depth of FeSi-core size (about 15μm) by heating at high temperature. The phenomenon in the compact inside could be explained by our newly proposed hypothesis "Exhaustion of diffusion-contributable atomic vacancies in core/rim structure".
In this study, it was investigated in relation to the above hypothesis whether TiC-core in the compact inside disappears or not due to solid-diffusion process by heating at 2073-2473 K which are extremely higher than the usual sintering temperature. As the result, it was judged that TiC-core in the compact inside really disappeared by solid-diffusion process at 2273-2473 K, differing from FeSi-core in the compact inside. Based on these results on Fe-66.7 at%Si alloy and the cermet, it was generally concluded that our new hypothesis can be applied to the alloy where the rim phase is a stoichiometric compound unable to dissolve the core elements and also the diffusion from the core to the rim is not thermodynamically allowed like in Fe-66.7 at% Si alloy, but not to the alloy where the rim is a solid solution able to dissolve the core elements and thus the diffusion from the core to the rim is thermodynamically allowed like in the cermet.View full abstractDownload PDF (10460K)
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