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Volume 27, Issue 8
Displaying 1-7 of 7 articles from this issue
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Takashi Inukai1980 Volume 27 Issue 8 Pages 249-251
Published: November 25, 1980
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSSiC powders having ultrafine grain size were prepared from CH3SiCl3 by means of plasma gas phase reaction in Ar gas atmosphere. The reaction was taken place in an induction plasma torch with a double tube or a triple tube. Powders obtained contain β-SiC, a small fraction of 2H-SiC, and even Si when the triple tube torch was used. Average grain size of β-SiC powders depends on the structure of the torches, the flow rate of the raw material, and the deposition place. The average grain size of β-SiC powders deposited at the torch tube under the flow rate of 5×10-4 mol/min is about 200A, and increases with increase of the raw material flow rate.View full abstractDownload PDF (1527K) -
Formation and Magnetic Properties in Mn-Zn-FerritesNoboru Yoneda, Shigeru Ito, Ikuo Katoh1980 Volume 27 Issue 8 Pages 252-255
Published: November 25, 1980
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSA duplex structure, in which some of large grains coexist with many small grains, has been observed in sintered Mn-Zn-ferrites when used the starting materials comprised of small powder and calcined at higher temperature. The large grains were suddenly formed through the nucleations after some induction periods. It was found that Avrami equation could be applied to the relation between net volume of large grains and sintering time. On the other hand, the duplex structure was also observed in the same ferrite when a small amount of Bi2O3 or V2O5 was added to the starting materials and sintered at the same condition. The mag-netic properties of the specimen having duplex structure were superior in B50, Br and permeability, and inferior in Hc and Curie temperature to those of the specimen havi,View full abstractDownload PDF (1729K) -
Yasuo Shibasaki, Shigeto Kanaoka, Takehisa Maeda, Shinji Tomura, Hiroy ...1980 Volume 27 Issue 8 Pages 256-260
Published: November 25, 1980
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSIn this work, an attempt was made to increase the plasticity of α-Fe2O3-water system. The influence of the variation in the grain size of a-Fe2O3 on its plasticity, and the effect of mixing with clay for increasing plasticity were examined by the Pfefferkorn method, and the results were compared with those of feldspar.
The results were summarized below;
(1) Appreciably good plasticity was found for fine-grained a-Fe2O3 (specific surface area larger than 3.8m2/g)-water system, while the plasticity of coarser α-Fe2O3 (2.4 m2, /g) and feldspar (1.0 m2/g)-water systems was too poor to be measured.
(2) The α-Fe2O3-clay-water system showed higher index of Pfefferkorn plasticity than that of feldspar-clay-water system at any mixing ratio. The difference was explained by the binary-particle packing model.
(3) Plasticity of hematite-clay-water and feldspar-clay-water systems was estimated numerically from the water retentivity (the difference in percent water loss between the bodies heated at 40°C and 100°C).View full abstractDownload PDF (363K) -
Osamu Iwatsu, Takanori Aoki, Teruhisa Watanabe1980 Volume 27 Issue 8 Pages 261-265
Published: November 25, 1980
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSIron-10%lead. (0-5)%copper compacts having about 20% porosity were sintered at each temperature from 330°to 1150°C and various properties of their sintered compacts were measured.
The results obtained were as follows;
1) The sweating of lead from iron-lead-copper compacts appeared at the temperature just above the melting point of lead, and the vapouring of lead from the compacts was brisk at the temperature over about 900°C. However, these phenomena were able to be suppressed by the increase of copper powder contents.
2) At the temperature over about 700°C, all the compacts began to shrink by the sintering between iron powder particles. But at the temperature over about 800°C, only the compacts having comparatively high contents of copper powder exihibited a tendency to expand by the copper alloying into the iron skeleton through the liquid lead-copper.
3) Pore-structures of the compacts containing no copper powder hardly changed at the temperature below about 1000°C. However, those of the compacts containing a little of copper powder were developed by melt-off pores of lead powder which appeared at temperature about 700°C.
4) Increase of the strength of the compacts was obstructed by the contents of lead powder. But the copper alloying into the iron skeleton caused by the addition of copper powder to the compacts could improve the above negative effect.
From the aboves, it was concluded that the sintering temperature for producing the iron-lead-copper sintered alloys for porous bearings must be selected in the range from 800°C to 900°C.View full abstractDownload PDF (3213K) -
Hisashi Suzuki, Koji Hayashi, Yutaka Kubo1980 Volume 27 Issue 8 Pages 266-270
Published: November 25, 1980
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe deformation behavior of TiC-Mo2C-Ni cermet affected by the additional TiN was mainly studied at 873-1273 K by means of three-point bend tests. It was found that the high temperature deformation of the cermet was highly suppressed by the addition of TiN with increasing test temperature, and that the creep rupture strength of the TiN-contained cermet became superior to that of usual WC-base alloys, in particular, at 1273 K and under low stresses. These results obtained in the TiN-contained cermet were considered to be due to the restraint of the dynamic recovery of binder phase during deformation.View full abstractDownload PDF (390K) -
Hisashi Suzuki, Koji Hayashi, Yutaka Kubo1980 Volume 27 Issue 8 Pages 271-272
Published: November 25, 1980
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe carbide structure of WC-17%TiC-40%ZrC-5%Ni cermet was mainly studied. It was found that the cermet showed an extremely fine carbide structure with high hardness and high strength when sintering cycle was specified. The structure was attributed to the phase separation of carbide solid-solution from one-phase to two-phases. Such a fine structure would similarly be obtained in other alloy systems.View full abstractDownload PDF (1441K) -
Hiroji Ogawa, Yoshihiro Kataoka1980 Volume 27 Issue 8 Pages 273-275
Published: November 25, 1980
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSA convenient and reliable sintering dilatometer for wide range use is expected as the most importantand interesting instrument for the investigation of powder metallurgy.
The authors have developed recently two types of special high temperature sintering dilatometers.These are:
No.1(HM type)which can be used up to 1600°C in H2 or neutral gas, and
No.2(VC type)which up to 1800°C in vacuum 10-3 Torr.
In this report, the concepts and a detail of these sintering dilatometers are described and possible applications for powder metallurgy are also shown.View full abstractDownload PDF (1049K)
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