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Volume 53, Issue 6
June
Displaying 1-9 of 9 articles from this issue
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Paper
Memorial Lecture of JSPM Award
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Tohru S. Suzuki, Yoshio Sakka, Koichi Kitazawa2006 Volume 53 Issue 6 Pages 479-487
Published: 2006
Released on J-STAGE: January 12, 2007
JOURNAL OPEN ACCESSThe controlled development of texture has recently become a topic of interest in ceramic processing, since it allows improved tailoring of the properties of a material. Anisotropic susceptibilities of feeble magnetic ceramics such as Al2O3 and ZnO are quite small. It is generally difficult to apply a magnetic field effectively in order to rotate fine feeble magnetic particles, since fine particles tend to spontaneously agglomerate due to strong attractive interactions (van der Waals forces). It is necessary to disperse the particles in a suspension in order to effectively utilize a magnetic field to rotate the particles. Colloidal processing is a powerful technique for controlling the stability of particles in a suspension. This processing can be used for production of textured ceramics with complex shapes by near-net-shape slip casting. In addition, the direction of textured polycrystalline can be controlled by the direction of the applied magnetic field.View full abstractDownload PDF (1770K)
Paper
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Hironori Suzuki, Takeaki Sakai, Yo Tomota2006 Volume 53 Issue 6 Pages 488-493
Published: 2006
Released on J-STAGE: January 12, 2007
JOURNAL OPEN ACCESSPure iron and Fe-0.6mass%P alloy were sintered at various temperatures from 1273K to 1623K. Magnetic properties, i,e., magnetic induction at 800 A/m (B8), maximum permeability (μm) and coresive force (Hc) of these alloys were measured using Cioffi type fluxmeter. Then the microstructures of those alloys were investigated using an optical microscope and an EMPA. Sintered density and the magnetic properties of the pure iron are almost constant in the sintering temperature range.
On the contrary, those of Fe-0.6mass%P are improved highly with elevating sintering temperature and shows B8=1.35T, μm=8mH/m and Hc=96AT/m at the sintering temperature 1623K. In the Fe-0.6mass%P sintered alloy, P atoms diffuse into the pure iron with an increase in sintering temperature, resulting in forming of the α phase. This densificates the alloy by α phase sintering and then changes pore shape from irregular to spherical. The magnetic properties of Fe-0.6mass%P sintered alloy are improved by mainly densification with spheroidization of the pores.View full abstractDownload PDF (1068K)
Special Issue:Control and Quantitative Evaluations in Powder Processing and Products
Summarization
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Takashi Ito2006 Volume 53 Issue 6 Pages 496
Published: 2006
Released on J-STAGE: January 12, 2007
JOURNAL OPEN ACCESSDownload PDF (144K)
Paper
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Takashi Yamaguchi, Katsuyoshi Kondoh2006 Volume 53 Issue 6 Pages 497-502
Published: 2006
Released on J-STAGE: January 12, 2007
JOURNAL OPEN ACCESSPreparation of magnesium silicide (Mg2Si) intermetallics film was achieved by the surface modification of the magnesium alloy using a pulse electric-current heating process together with Si powder. In this study, the change of the load pressure in the pulse electric-current heating process enables the density control of Mg2Si film. Some results of SST to evaluate the corrosion resistance indicated that AZ31 substrate with high pressure Mg2Si coating showed no damage after 96h. On the other hand, the subdtrate with no coating was corroded within only 1h, and showed remarkably damaged surfaces. Pin-on-disk type wear test under an oil lubricant indicated that a friction coefficient was low and stable in using AZ31 alloy disk specimen coated with Mg2Si film.View full abstractDownload PDF (1418K) -
Gen-yo Kaneko, Mihoko Mori, Hiroyuki Kitagawa, Kazuhiro Hasezaki, Hito ...2006 Volume 53 Issue 6 Pages 503-506
Published: 2006
Released on J-STAGE: January 12, 2007
JOURNAL OPEN ACCESSCoal fly ash-based bulk materials were prepared by spark plasma sintering (SPS). As-received and fired powders were used as starting materials, where firing was treated at 1200°C for 24 hours in the air. Sintering temperature changes depending on starting materials; that is, 730°C for as-received and 830°C for fired powders, respectively. The obtained samples were highly-densed materials, where density was 2.8×103kg/m3 for sintered at 1070°C using fired powders. X-ray diffraction patterns of sintered materials indicate that mullite phase is predominant in all samples. SiO2, Al2O3, and Fe2O3 phases were also confirmed from result of electron probe microanalysis (EPMA). Vickers hardness of sintered fly ash was 726∼821, indicating that these materials have possibilities for application as structural materials.View full abstractDownload PDF (741K) -
Kazuhiro Hasezaki, Gen-yo Kaneko, Chika Yoshida, Hiroshi Araki, Hiroyu ...2006 Volume 53 Issue 6 Pages 507-509
Published: 2006
Released on J-STAGE: January 12, 2007
JOURNAL OPEN ACCESSEu2+ and Dy3+ co-doped strontium aluminate (SrAl2O4) phosphors have been considered as strong and lasting phosphorescent eco-materials for chemically stable, safe making and long lasting phosphorescence process without radiation, compared with sulfide phosphors. In this study, Eu2+ and Dy3+ co-doped strontium aluminate (SrAl2O4) phosphors were prepared by spark-plasma sintering (SPS) at 873 K, 1273 K and 1623 K. The structures of Eu2+ and Dy3+ co-doped SrAl2O4 were investigated by X-ray diffraction (XRD), differential thermal analysis-thermo gravimetric analysis (DTA-TG), and shrinkage during the sintering process. It was found that synthesis of SrAl2O4 over 1273 K, two stage shrinkage temperature zone blow 1073 K and over 1573 K. Phosphorescences of Eu2+ and Dy3+ co-doped SrAl2O4 were observed at 450-650 nm.View full abstractDownload PDF (275K) -
Hironori Sasaki, Teruo Asaoka2006 Volume 53 Issue 6 Pages 510-514
Published: 2006
Released on J-STAGE: January 12, 2007
JOURNAL OPEN ACCESSHydroxy-Apatite (HAp), commonly used as a biomaterial, is one of the primary components of bones and teeth and exhibits a high level of biocompatibility. However, it has poor mechanical properties due to its brittle nature. Recently, several attempts have been made to develop functionally graded materials (FGM) by combining Ti or Ti alloys, known for their superior mechanical properties, with HAp. The present study aimed to develop a material with a radially graded structure consisting of Ti in the center and HAp on the surface, using spark plasma sintering for artificial bone preparation. In the experiments, both the temperature distribution in dice upon sintering, and the residual stress distribution at the interface of each layer after sintering, were analized by FEM in order to obtain a method for examining optimal production conditions.View full abstractDownload PDF (798K) -
Norihiko Miyashita, Ryoma Tsukuda, Isamu Yashima, Hidehiko Kobayashi2006 Volume 53 Issue 6 Pages 515-522
Published: 2006
Released on J-STAGE: January 12, 2007
JOURNAL OPEN ACCESSp-type Bi0.4Sb1.6Te3.0 sintered materials were prepared by hot pressing and combination of pressureless sintering and hot pressing, and the effect of pressureless sintering on the microstructures and thermoelectric properties of the sintered materials were investigated. Samples prepared by hot pressing after pressureless sintering had the microstructures with grain growth and showed higher power factors in comparison with samples prepared by hot pressing and pressureless sintering after hot pressing. It is considered that the higher power factors attribute the increase in the mobility caused by increasing in the grain size due to pressureless sintering before hot pressing. The thermal conductivities also showed a little higher values due to the increases in both carrier and lattice thermal conductivities. Consequently, the sample prepared by hot pressing after pressureless sintering showed the highest figure of merit of Z = 3.69×10-3 K-1 for a sintering temperature of 803 K.View full abstractDownload PDF (1274K) -
Yuki Maeno, Masaaki Miyamoto2006 Volume 53 Issue 6 Pages 523-528
Published: 2006
Released on J-STAGE: January 12, 2007
JOURNAL OPEN ACCESSβ-FeSi2 powders were prepared by solid-state reaction between iron and silicon powders. After the reaction, sintered n-type and p-type β-FeSi2 were prepared by hot pressing at 900°C for 1h under 55MPa in Ar. The effects of the amount of KCl and the most suitable reaction temperature on the solid-state reaction were investigated. β-FeSi2 powder was prepared by adding 5.0mass%KCl at 850°C for 5h in Ar. After the reaction, sample crushed by ball milling and KCl was removed by washing with pure water. But in hot pressed samples, small amount of ε-phase appeared. To reduce the ε-phase, excess 3.0mass%Si were added to the β-phase powders before hot pressing. The relative density of the obtained sintered body was about 92%.
Thermoelectric properties of sintered body of β-phase only (Fe0.95M0.05Si2.21, M=Co, Cr) and sintered body including ε-phase (Fe0.95M0.05Si2.1, M=Co, Cr) were evaluated. As a result, power factor (α2/ρ) of sintered body including ε-phase was superiorer to sintered body of β-phase only.View full abstractDownload PDF (3076K)
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