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Volume 49, Issue 12
Displaying 1-15 of 15 articles from this issue
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Yoshimi Watanabe2002 Volume 49 Issue 12 Pages 1057-1062
Published: December 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe fabrication of the intermetallic compound-dispersed functionally graded materials (FGMs) by a centrifugal method can be classified into two categories based on the relation between the processing temperature and the liquidus temperature of master alloy. One is a centrifugal solid-particle method where the processing temperature is lower than the liquidus temperature of the master alloy and the dispersed solid phase in the master alloy remains in a liquid matrix. The other is a centrifugal in-situ method where the processing temperature is higher than the liquidus temperature of the master alloy. The FGMs introduced in this review are Al-Al3Ti FGM fabricated by the centrifugal solid-particle method, Al-Al3Ni FGM, Al-Al2Cu FGM fabricated by the centrifugal in-situ method and Al-(Al3Ti+Al3Ni) FGM fabricated by both methods. In this review, the outline of the method is introduced briefly, and then described some recent studies about the microstructures of the FGMs fabricated by the centrifugal solid-particle and/or in-situ methods.View full abstractDownload PDF (7375K) -
Fumio Watari, Hideomi Kondo, Rika Miyao, Mamoru Omori, Akira Okubo, To ...2002 Volume 49 Issue 12 Pages 1063-1069
Published: December 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe coexistence of Ti and hydroxyapatite (HAP) makes HAP decomposed at the sintering process heated at more than 1000°C in vacuum or Ar atmosphere. Spark plasma sintering (SPS) method could make the stable functionally graded materials (FGM) with the gradual change of concentration in the longitudinal direction from pure Ti to 100% HAP (Ti/100HAP) at the sintering temperature as low as 850 °C. However, sintering is insufficient. To increase the degree of sintering the dependence of mechanical properties on sintering pressure was investigated. By increase of sintering pressure from 40 to 80 MPa compression strength was increased from 48 to 88 MPa, and flexural strength from 6 to 36 MPa. Brinel hardness decreased monotonically from Ti region to HAP inside FGM specimen. This decreasing gradience inside implant contributes to stress relaxation in the implanted region of bone where the compatibility with tissue is essential in biomechanical properties. Animal implantation tests in hard tissue showed that the tissue reacted gradiently in response to the graded composition of FGM implant. The maturation of new bone occurred from th earlier stage in the HAP rich region. Functionally graded implants could thus satisfy the biocompatibility in both mechanical properties and biochemical affinity to osteogenesis.View full abstractDownload PDF (7565K) -
Sukasem Kangwantrakool, Kunio Shinohara2002 Volume 49 Issue 12 Pages 1070-1075
Published: December 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIn order to design a microstructure of a sintered composite material as uniform as possible, an experimental investigation was carried out by preparation of WC particles coated with Co, Al2O3, and TiC by high-speed rotational impact blending. The composite material was then fabricated by spark plasma sintering. The compositions were changed with different ratios of TiC to Al2O3. The comparatively uniform microstructure was obtained corresponding to the coated particle model. The composition of 55WC-10Co-30TiC-5Al2O3 yielded the highest values of Vickers hardness and transverse rupture strength due to uniform dispersion of each component and generation of A12O3 particulate reinforcement effect with less pores than other compositions.View full abstractDownload PDF (5598K) -
Masao Kaneko, Min-young Jun, Masato Imamura, Akira Yanagisawa2002 Volume 49 Issue 12 Pages 1076-1081
Published: December 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSSintering is used for fabrication aluminum fiber products, however this method involves considerable difficulty due to the presence of oxidized layer on the surface. On the other hand, the aluminum brazing material, which is mainly used in the fabrication of radiators for automobile, is to be sintered easily with keeping original characteristics of aluminum because its brazing layer works as binder.
In this study, investigations were carried out on fabrication aluminum fiber products by using aluminum brazing fibers produced by coiled sheet shaving, and the sintering conditions of the aluminum brazing fiber for porous products were reviewed. The results showed that at the sintering temperature of 873 K, fiber porous products with a tensile strength of 1.2 Mpa can be fabricated. In addition, by mixing aluminum brazing fibers to pure aluminum fibers, fiber porous products with parent material made of pure aluminum can be fabricated. It was also confirmed that aluminum sintered products with large porosity of 75% to 88% can be obtained by changing the mixture rate of aluminum brazing fibers.View full abstractDownload PDF (4281K) -
α-Bi2O3-HNO3-H2O SystemYuji Nishio, Koji Amezawa, Masayoshi Horibe, Naoichi Yamamoto2002 Volume 49 Issue 12 Pages 1082-1088
Published: December 15, 2002
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe formation diagram of α-Bi2O3-HNO3-H2O system was studied using hydrothermal or "wet" method. Three kinds of compound of bismuth basic nitrate complex oxides were separated as single phases and determined their chemical compositions. The existence of these phases was previously found by XRD measurements, although those phases have been obtained only as mixture of multi phases precipitates. The new compounds have the chemical composition of Bi2(NO3)O2(OH)⋅7H2O, Bi2(NO3)O2(OH)⋅H2O, and Bi4(NO3)O2(OH)7, respectively. At the same reaction conditions of temperature (above 60°C) and pH in the a-Bi2O3-HNO3-H2O system and the BiONO3-KOH-H2O systems, it was affirmed that the same kind of precipitates were formed regardless of the kind of starting reagents.View full abstractDownload PDF (1779K) -
Akihiro Matsumoto, Keizo Kobayashi, Toshiyuki Nishio, Kimihiro Ozaki2002 Volume 49 Issue 12 Pages 1089-1093
Published: December 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSEffect of boron addition on structure and mechanical properties of FeAl-WC have been investigated. Elemental powders of iron, aluminum and boron powders have been used as starting materials for MA and mixed to give the desired composition of Fe-40at%Al+0-5 at%B. Boron addition leads to fine milled powders and improves mechanical properties of Fe-40at%Al compacts. Milled Fe-40 at%Al powders with 3at% B have been blended with WC powders and consolidated using pulse current sintering process at 1373-1473 K. 3at%B-added FeAI-50vol%WC has had high vickers hardness 1230 Hv and transverse rupture strength 1.77 GPa, while no B-added FeAl-50vol% WC has had 1080 Hv and 1.10 GPa respectively. This is caused by improvement of dispersion of WC paricles in FeAl matrix.View full abstractDownload PDF (3381K) -
Koichiro Morimoto, Kenichi Kato, Kazunori Igarashi, Ryoji Nakayama2002 Volume 49 Issue 12 Pages 1094-1097
Published: December 15, 2002
Released on J-STAGE: July 12, 2010
JOURNAL FREE ACCESSThe present authors examined magnetic properties of anisotropic Nd10.1Pr2.9Fe74.6-Co5.8B6.2Zr0.1Ga0.3HDDR powders prepared from strip cast alloy flakes which were annealed at various temperatures before HDDR treatment. Br's and (BH)max's of the powders are increased with increase in annealing temperature for the starting alloy flakes, which can be ascribed to the growth of original Nd2Fe14B grains. The bonded magnet of the powder obtained from the optimally annealed alloy flakes, exhibits Br of 1.05 T, HcJ of 1100 kA/m, and (BH)max of 199 kJ/m3, which are much superior to those from the conventional book-mold cast ingots. This would be related to the elimination of α-Fe phase in the strip cast flakes.View full abstractDownload PDF (4467K) -
Liew Loy Seng, Masahiro Umeda, Katsuhiro Maekawa, Shinichi Iida, Tomoy ...2002 Volume 49 Issue 12 Pages 1098-1103
Published: December 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSSelective laser sintering (SLS) using resin-coated stainless steel powder has recently been developed in the area of direct metal tooling. Improvements in the strength and dimensional accuracy of parts have let us to investigate the influence of parameters such as laser power, scan speed and scan spacing. It is also important to obtain a knowledge of the fundamentals of furnace sintering and metal infiltration. In the case of the use of bronze as an infiltrant, the temperature profile, holding time, and the arrangement of tabs have been successfully determined in the present study. The replacement of RapidSteel 2.0 by LaserForm ST100 in metal layer sintering by the SLS method has attracted much attention from industrial users. The present paper also discusses differences in the sintering characteristics of these two materials. When bronze is infiltrated at 1040°C the ST100 object has a tensile strength of 537 MPa, which is 21.1% lower than that of the RS2 part.View full abstractDownload PDF (5585K) -
Motohiro Miyasaka, Tadashi Momono2002 Volume 49 Issue 12 Pages 1104-1112
Published: December 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe remaining porosity of a bearing's frictional surface was evaluated after run-in of the bronze-based oilimpregnated sintered bearings. The linear relation was evaluated as a result of the Sommerfeld number and the bearing surface's porosity, the results confirmed the bearing surface's porosity after run-in, using the Sommerfeld number. When the Sommerfeld number was more than 0.45, the bearing surface's porosity was more than 15%. When the Sommerfeld number was between 0.01 and 0.45, the bearing surface's porosity was between 2 and 15%. And, when the Sommerfeld number was less than 0.01, the bearing surface's porosity was less than 2%. A detailed observation of the frictional surface showed that several pores were filled with sludge, when severe wear occurred the Sommerfeld number was less than 0.01. In the case of an enclosed outside diameter and the case of an opened outside diameter, both showed almost the same results.View full abstractDownload PDF (7873K) -
Baolong Shen, Hisamichi Kimura, Akihisa Inoue2002 Volume 49 Issue 12 Pages 1113-1118
Published: December 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe effect of ferromagnetic metal Co on the glass-forming ability and magnetic properties for the Fe75-xCoxGa5P12C4B4 glassy alloys was investigated. The additions of 10 to 15 at% Co were found to be effective for the extension of the supercooled liquid region (ΔTx) defined by the difference between the glass transition temperature (Tg) and crystallization temperature (Tx). The ΔTx value is 37K for the Fe75Ga5P12C4B4 alloy and increases to 48K for the 10, 12.5 and 15at% Co alloys. The liquidus temperature (T1) of the 10, 12.5 and 15 at% Co alloys decreased by the addition of Co and the reduced glass transition temperature (Tg/T1) increased. The largest Tg/T1 is 0.61 for the Fe65Co10Ga5P12C4B4 alloy. These glassy ribbon alloys exhibit good soft magnetic properties of 1.15 to 1.3 T for saturation magnetization and 2.4 to 3.3 A/m for coercive force. Based on the large ΔTx and high Tg/T1 values, we tried to prepare bulk glassy Fe75-xCoxGa5P12C4B4 (x=10, 12.5, 15) rods in a cylindrical form with different diameters. The glassy single phase was obtained in the diameter of 1.5mm in the composition range of 10 to 15 at% Co. Furthermore, for the Fe65Co10Ga5P12C4B4 alloy, a bulk glassy rod with good soft magnetic properties in diameter of 2mm was formed.View full abstractDownload PDF (407K) -
[in Japanese]2002 Volume 49 Issue 12 Pages 1120
Published: December 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (117K) -
Nanao Horiishi2002 Volume 49 Issue 12 Pages 1121-1127
Published: December 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIron oxide pigment is commonly called Bengala in Japan. The name did not originate from old Japanese language, but from Portuguese. In this paper a historical survey of Bengala is given from ancient age to the present days. Bengala was one of the earliest coloring pigments used by human beings and still has its important roles in our modern life. It has been well known that in ancient ruined caves animals were drawn on the rocks by using natural iron oxide pigments. Red colored bricks in the old Indus civilizations (4500 years ago) were made from red clay. In ancient China (about 2nd. Century A.C) magnetic iron oxide was first applied to Direction Indicating Tools so called Shinan-gyo. In the present days, Bengala has been one of the most important materials in modern industries, especially electronics. From now on, Bengala would give the solutions to serious problems, i.e. recycling natural resources, earth environment preservation and energy saving which are the important key words in the 21st century.View full abstractDownload PDF (1873K) -
Takashi Takeda, Kasori Takahashi, Kyota Uheda, Hirotsugu Takizawa, Tad ...2002 Volume 49 Issue 12 Pages 1128-1133
Published: December 15, 2002
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSEu2+activated Sr2Al6O11 and Sr4Al14O25 were prepared with B2O3 additives at the temperatures of 1100°C to 1300°C in flowing 5% H2/Ar gas. These products were characterized by XRD analysis, UV and VUV spectroscopy and so forth. The precise crystal structure of Sr2Al6O11 was first determined by Rietveld method. Between the sheets of the edge shared AlO6 octahedron, the corner shared AlO4 tetrahedral linkages of Sr2Al6O11 demonstrated a quite different fashion than that of Sr4Al14O25 According to the UV-Vis. and VUV spectra, an intense broad emission was observed near 460 nm in Sr2Al6O11:Eu2+, and two emission peaks were recognized at 409 nm and 496 nm in Sr4Al14O25:Eu2+. It was found that such emission profile and the thermal degradation of luminescence were fairly sensitive to every structural characteristic.View full abstractDownload PDF (398K) -
Iwao Sakaihara, Katsuhisa Tanaka, Takashi Wakasugi, Rikuo Ota2002 Volume 49 Issue 12 Pages 1134-1138
Published: December 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSBaTiO3 and BaTiO3:Gd3+ ultrafine particles were prepared by the sol-gel method. 0.1mol% of Ba2+ was substituted by Gd3+ for BaTiO3:Gd3+ powders. Electron spin resonance measurements were carried out for these powders to clarify the crystal structure. The crystallite size of these particles was determined by X-ray diffraction analysis with the aid of Scherrer's equation as well as transmission electron microscopy. The crystallite size of these particles is 25 to 40 nm. The profile of the electron spin resonance spectrum at room temperature for BaTiO3: Gd3+ powder suggests that the phase present in these powder samples possesses an intermediate structure between the tetragonal and cubic phases at room temperature.View full abstractDownload PDF (3167K) -
Soshu Kirihara, Yoshinari Miyamoto, Mitsuo Wada Takeda, Kazuaki Sakoda2002 Volume 49 Issue 12 Pages 1139-1144
Published: December 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMillimeter order photonic crystals composed of epoxy lattices containing titania-based ceramic particles and having a three-dimensional diamond structure were fabricated by using a stereolithograpy process. The inverse diamond structures composed of the air lattices with the diamond structure in dielectric bulks were also processed which exhibited perfect bandgaps in microwave frequency range. The normal and inverse lattice structures were stretched gradually to diffract the microwave in wide ranges. These graded lattice structures were designed according to the band calculation using a plane wave propagation method. An electromagnetic filter composed of the graded lattice structure with a missing layer realized the selective transmission of the microwave.View full abstractDownload PDF (6422K)
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