Journal of the Japan Society of Powder and Powder Metallurgy
Online ISSN : 1880-9014
Print ISSN : 0532-8799
ISSN-L : 0532-8799
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Volume 58, Issue 12
December
Displaying 1-10 of 10 articles from this issue
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Paper
Paper
  • Relationship between Ferroelectric Property and Crystal Structure of Pb(Zr, Ti, Nb)O3 with High Nb Content
    Yasushi Idemoto, Takuma Mizoguchi, Naoto Kitamura
    2011 Volume 58 Issue 12 Pages 703-709
    Published: 2011
    Released on J-STAGE: February 01, 2012
    DOIhttps://doi.org/10.2497/jjspm.58.703
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    Pb(Zr, Ti)O3 (PZT) has been widely used as an actuator, a sensor and ferroelectric memory (FeRAM) and so on, due to its high piezoelectricity and ferroelectric performance. In this study, we focused on Nb-substituted PZT, Pb(Zr, Ti, Nb)O3, with Nb contents of 10∼20 mol%. We examined the dependence of the ferroelectric property on Nb content, and investigated the crystal structure by Rietveld analysis using neutron diffraction data. As a result, it was demonstrated that sintered compacts of Pb(Zr, Ti, Nb)O3 with a single phase of the perovskite structure were successfully prepared when the Nb substitution content was up to 10 mol%. It was also found that the Nb substitution made the grain size smaller, and that the average size was 1∼2 μm. P-E hysteresis measurements clarified that the remanant polarization, Pr, was improved by the 10 mol% Nb substitution although the higher Nb content than 10 mol% resulted in the worse ferroelectric property. From the crystal structure analysis, it was indicated that a distortion in the crystal was relaxed by the Nb substitution and thus the spontaneous polarization was decreased with increasing Nb content.
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  • Relationship between Annealing and Biomechanical Compatibility of Porous Titanium
    Yuki Sakamoto, Yuji Kawakami
    2011 Volume 58 Issue 12 Pages 710-714
    Published: 2011
    Released on J-STAGE: February 01, 2012
    DOIhttps://doi.org/10.2497/jjspm.58.710
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    Titanium has widely been used as a biomaterial because of its excellent biocompatibility. However, problems with respect to biological reaction and fitness of elastic modulus for human bone have yet to be solved. Porous titanium is expected to be a promising material to solve these problems. The aim of this study is to clarify the effect of the porous titanium with and without annealing on the biomechanical compatibility. Porous titanium was made by spark plasma sintering. And the parts of the samples were annealed. The samples were machined from the sintered compacts for the evaluation of the mechanical properties. The tensile strength of porous titanium was 42 MPa, which is lower than half the value for human cortical bone, while the annealed samples was 95 MPa, a value somewhat close to that of the human cortical bone. We found that the mechanical properties with annealing porous titanium indicated a value close to the human bone.
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Special Issue: New Development of Diverse Powder Forming Processes Part II
Review
  • Present Status for The Development of Metal-Based Heat Dissipative Materials
    Kiyoshi Mizuuchi, Kanryu Inoue, Yasuyuki Agari, Masakazu Kawahara, Yuk ...
    2011 Volume 58 Issue 12 Pages 717-726
    Published: 2011
    Released on J-STAGE: February 01, 2012
    DOIhttps://doi.org/10.2497/jjspm.58.717
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    High-performance thermal management materials should have high thermal conductivities and low coefficients of thermal expansion (CTE) for maximizing heat dissipation and minimizing thermal stress and warping, which are critical issues in packaging of power semiconductors, light-emitting diodes and micro electro mechanical systems. Thermal stress and warping arise from CTE differences, which become significant in advanced electronic devices because of high heat generated, for example, when high-power laser diodes or high integration level of IC are in use. To ensure ideal or desired performance and adequate life of these electronic devices, it is necessary to decrease the junction temperature between two components to temperatures lower than: 398 K for military and automobile logic devices; and 343 K for some commercial logic devices. In the case of high-power density devices, the allowable temperature range is limited in the package base and die-attach thermal resistances. In any cases, the development of thermal management materials is significant in electronics fields.
    In order to fabricate high-performance thermal management materials with ultra-high thermal conductivities and low CTEs, we have recently initiated a series of investigations, where metal-matrix composites (MMCs) containing high thermal conductive fillers were uniquely fabricated. In our study, to avoid the damage of filler particle surfaces, spark plasma sintering (SPS) processing was used as a processing technique. In the present review, thermal properties of particle dispersed MMCs fabricated using SPS process in our recent works are introduced in comparison with those produced using various fabrication techniques by other researchers.
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Paper
  • Fabrication of ZrO2 Solid Solution Ceramics Containing Al2O3 Having High Bending Strength (σb≥1 GPa) and High Fracture Toughness (KIC≥20 MPa·m1/2) Simultaneously by Pulsed Electric-current Pressure Sintering (PECPS)
    Kengo Shibaya, Hideyuki Sato, Hiroyuki Matsuda, Katsuya Takaoka, Masak ...
    2011 Volume 58 Issue 12 Pages 727-732
    Published: 2011
    Released on J-STAGE: February 01, 2012
    DOIhttps://doi.org/10.2497/jjspm.58.727
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    ZrO2 solid solution (ss) ceramics containing 25mol%Al2O3 and 1.125mol%Y2O3, i.e., 75mol%ZrO2(1.5mol%Y2O3:1.5Y)-25mol%Al2O3 ceramics, have been fabricated by sintering cubic ZrO2 (ss) nanoparticles prepared via a sol-gel process with a pulsed electric-current pressure sintering (PECPS) at 1100°∼1350°C for 10 min under 60 MPa in Ar. Dense tetragonal-ZrO2 (ss) ceramics with a small amount of α-Al2O3, sintered at 1300° to 1350°C, were composed of 0.2-0.3 μm grains with a high relative density of ≥97.5 %. They showed extreme high bending strength (σb≥1 GPa) and high fracture toughness (KIC≥20 MPa·m1/2) simultaneously. High-resolution TEM observation revealed that these mechanical properties were originated from homogeneous distribution of α-Al2O3 particles in the nanometer-grain matrix of t-ZrO2; the precipitation of α-Al2O3 could be achieved by adopting the solid solution powders containing α-Al2O3 and PECPS.
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  • Effect of Oxygen-enriched h-BN Powder on the Property of h-BN/Feldspar Composite
    Mitsuya Hashii, Hiroyuki Yamada, Shoichi Kume
    2011 Volume 58 Issue 12 Pages 733-737
    Published: 2011
    Released on J-STAGE: February 01, 2012
    DOIhttps://doi.org/10.2497/jjspm.58.733
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    h-BN/feldspar composite was sintered under normal pressure at low temperature in air. Using oxygen-enriched h-BN powder was effective to increase the strength of composites. h-BN powder included 40mass% B2O3, and feldspar which melting point was nearly 1500 K, were mixed at a volume ratio of 1:1. The mixed powder was sintered without pressure at 1573 K in air. The average bending strength of the compacts was 47 MPa. It was revealed that the existence of melted B2O3 during sintering was the key point for both getting good wettability of the interface between h-BN and feldspar, and getting high strength of the composites.
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  • Effect of Pre-melted Feldspar on the Property of h-BN/Feldspar Composite
    Mitsuya Hashii, Hiroyuki Yamada, Shoichi Kume, Noriaki Yamada, Kazuo I ...
    2011 Volume 58 Issue 12 Pages 738-743
    Published: 2011
    Released on J-STAGE: February 01, 2012
    DOIhttps://doi.org/10.2497/jjspm.58.738
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    h-BN/feldspar composite was sintered without pressure at low temperature in air. h-BN and feldspar powders were mixed at the volume ratio of 1:1. The h-BN powder contained 40mass% B2O3. The feldspar was pre-melted and then milled. The melting point of as-received feldspar was nearly 1500 K. The mixed powder was sintered without pressure at 1473 K in air. The bending strength of the compact was 59 MPa. This value was higher than that of the compact sintered using as-received feldspar. It was also higher value than that of the compact, which contained the pre-melted feldspar, sintered at 1573 K. Additionally, it would be important using oxygen-enriched h-BN powder which contains B2O3 at not only the surfaces but also insides.
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