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Volume 34, Issue 1
Displaying 1-8 of 8 articles from this issue
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[in Japanese], [in Japanese]1987 Volume 34 Issue 1 Pages 1-7
Published: January 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (445K) -
Hisao Suzuki, Takaharu Miyazaki, Shinsuke Hayashi, Saito Hajime1987 Volume 34 Issue 1 Pages 8-13
Published: January 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe powders were prepared from mixed alkoxide solutions of Al and Ti to investigate A12TiO5 formation reaction and sinterability of resultant powders. HCI-catalyzed hydrolysis of metal alkoxides enhanced the agglomeration of the resulting powders and the formation of anatase at low temperature. However, the conversion of A12TiO5 in a sintered body was almost independent upon the hydrolysis conditions, since A12TiO5 was formed through the solid-solid reaction of rutile and corundum. A uniform addition of Mg into the A12TiO5 through solgel technique made it possible to reduce the crack size of sintered body due to a homogeneous nucleation. Average thermal expansion coefficients, bulk density and flexural strengths of sintered bodies had maximum values in a certain amount of MgTi2O5 addition.View full abstractDownload PDF (1544K) -
Effect of Composition on the Particle Shape and the Magnetic Properties of SrO⋅nFe2O3 with 5.4≤n≤6.4Yuji Kaneko, Shuji Anamoto, Atsushi Hamamura1987 Volume 34 Issue 1 Pages 14-17
Published: January 25, 1987
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSSamples of SrO⋅nFe2O3 with 5.4≤n≤6.4 were prepared by calcination at 1275°C in air for I h of mixtures of SrCO3 and a-Fe203. Each calcined sample was pulverized in the presence of extremely slight amounts of CaCO3 and SiO2 as additives, compacted under the pressure 350 kg/cm2 in a magnetic field 12kG, and sintered at 1220±10°C in air for 1 h.
Composition dependences of the particle shape and the magnetic properties of the calcined samples and of the sintered magnets containing 0.75 wt% CaO and 0.6 wt%SiO2 were investigated.
The particle shape of the calcined sample was changed drastically by the composition. The saturation magnetization (σs) decreased, while the intrinsic coercivity (iHc) increased with decreasing SrO content in the calcined sample.
On the other hand, the residual magnetization (Br) increased and iHc decreased with decreasing SrO content in the sintered magnet, depending on the grain shape and size in the magnet.
The high performance magnet could be prepared with n??5.9 under these experimental conditions.View full abstractDownload PDF (5021K) -
Effect of the Size of Nb2Sn ParticleTakanori Watari, Takuma Takasu, Syoji Nakamura, Akio Kato1987 Volume 34 Issue 1 Pages 18-21
Published: January 25, 1987
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSSuperconducting transition temperature (Tc) and critical current density (Jc) of the composite in which Nb3Sn particles with the average size of 0.07-62μm were dispersed in silver were measured. Tc increased as the increase of the volume fraction of Nb3Sn (VNb3Sn) and the diameter of Nb3Sn particle (dNb3sn). Jc increased as the increase of VNb3Sn⋅Jc showed a maximum at around dNb3Sn=0.10μm. The effect of dNb3Sn on Tc and Jc could be explained by the superconducting proximity effect. Tc and Jc of Nb3Sn-Ag composite increased by heat treatment above 962°C (m.p. of Ag) due to the improvement of contact between Nb3Sn particles and Ag matrix, but decreased by the heat treatment at 1100°C and 1200°C in the case of dNb3Sn=0.12μm, and at 1400°C in the case of dNb3Sn=1.0μm owing to the elution of SO from Nb3Sn into Ag matrix.View full abstractDownload PDF (1486K) -
Hisashi Suzuki, Hideaki Matsubara, Kunio Shibuki1987 Volume 34 Issue 1 Pages 22-25
Published: January 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe diamond deposition from (CH4+H2) mixed gas on WC-5%Co alloy substrate by means of hotfilament method was investigated. In this study, the distance(d) between filament and substrate, and the filament temperature (Tf) were tried to be shorter and higher, respectively, than the values (d=10 mm, Tf=2273 K) taken in the previous studies by the authors. It was found that the amount of deposited diamond and the upper value of CH4 concentration were increased with shorter d and higher Tf, when the substrate temperature was controlled. It was also found that the growth rate of diamond particles as high as about 3.5 μm/hr could be obtained under a specified condition.View full abstractDownload PDF (2971K) -
Koji Hayashi, Bao-quan Yang, Atsuyuki Nakano, Mamoru Kosakai1987 Volume 34 Issue 1 Pages 26-32
Published: January 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe Si3N4-(4-12)mo1%Y2O3-6 mo1%Al2O3 compacts were sintered under 0.1 MPa of nitrogen at 2023 K for 0.9-36 ks. The microstructure and some properties of the sintered compact were investigated.
The results obtained were as follows; (1) The weight loss of the compact due to the sintering, the relative density and the thickness of the microstructural heterogeneous layer near the surface of the compact increased with increasing sintering time (ts). (2) The crystalline grain boundary phases were found to be Y10(SiO4)6N2 or Y4Si2O7N2 at short ts and YSiO2N or Y2Si3O3N4 at long ts. The crystalline grain boundary phases except for YSiO2N were observed as large white domains in the optical micrographs. (3) The room temperature transverse-rupture strength and hardness increased in general with increasing ts. The maximum strength was generally obtained in 8-10 mol% Y2O3 compact at any ts. The strength, even for the compact with Y2O3 content as small as 4 mo1%, attained to 0.85 GPa at long ts. These results were discussed in relation to the relative density, the microstructural defects which acted as fracture source, the grain boundary phase and the grain size of Si3N4 particles.View full abstractDownload PDF (5587K) -
Nobuyasu Kawai, Minoru Hirano, Tsuneo Tatsuno, Katsuhiko Honma1987 Volume 34 Issue 1 Pages 33-39
Published: January 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSNitrogen free and nitrogen containing SKH51, 55V, 57 and 10 high speed steels were produced by HIP'-ing gas atomized powders. Nitrogen was added to steels by heat-treating the powders in nitrogen gas before HIP'ing. The properties of abovementioned steels were compared with those of conventional steels, and the following results were obtained.
1) By adding nitrogen to high speed steels, the decrease of incipient melting temperature was not observed.
2) The amount of retained austenite was increased by the addition of nitrogen, especially, higher vanadium steels had more amounts of retained austenite because of more nitrogen contents.
3) The continuous cutting performance at low cutting speed and intermittent cutting performance were significantly improved by the addition of nitrogen.
4) In case of nitrogen free P/M steels, the bend strength was not reduced by the increase of vanadium content, because the change in carbide size was not observed among 4 kinds of P/M steels.
5) Higher vanadium P/M steels exhibited a better intermittent cutting performance than lower vanadium P/M steels. However, in case of conventional steels, higher vanadium steels exhibited the reverse property.View full abstractDownload PDF (2601K) -
Nobuyasu Kawai, Minoru Hirano, Tsuneo Tatsuno, Katsuhiko Honma1987 Volume 34 Issue 1 Pages 40-44
Published: January 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSBehavior of nitrogen absorption into gas atomized high speed tool steel powders has been studied by using thermo-balance in nitrogen atmosphere from 950°C to 1195°C.
As the results, it has become clear that the absorbed nitrogen contents of high speed tool steel powders are in proportion to vanadium contents of the powders and the nitrogen absorbed exists as vanadium carbonitrides in the powders. Also, the nitrogen contents of the powder are not dependent on particle size, but on nitriding temperature. And the saturated nitrogen contents are higher at lower temperature.
Nitrogen absorption rate into the powders is faster as the particle is finer and nitriding temperature higher.
It was found that the rate-determining process of nitrogen absorption into the powders is the reaction of nitrogen molecule dissociation to atomic nitrogen on the particle surface.View full abstractDownload PDF (333K)
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