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Volume 29, Issue 2
Displaying 1-6 of 6 articles from this issue
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Kiichi Oda, Tetsuo Yoshio, Katsuaki Takahashi1982 Volume 29 Issue 2 Pages 39-44
Published: February 25, 1982
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSBa1-xSrxFe12O19 particles were prepared by the glass-ceramic method. Ba1-xSrxFe12O19 particles precipitated by heat-treatment of BaO-SrO-B2O3-SiO2-Fe2O3 glass in the temperature range from 600° to 900°C. The particles showed a habit as hexagonal platelet with fairly uniform dimension, which could be taken out easily of the glass matrix by leaching with a dil. HCl solution.
In the case of SrO rich glass, 4SrO⋅B2O3⋅SiO2 precipitated abruptly and consequently Ba1-xSrxFe12O19 particles precipitated with a small dimension of 0.1-0.4μm. On the other hand, BaFe12O19 particles with a relatively larger dimension of 0.1-2μm were obtained from a SrO free glass.
Ba1-xSrxFe12O19 particles with 0.43 pm in size, prepared under the heat-treatment condition at 875°C for 5 hr, showed coercive force of 6000 Oe except for BaFe12O19. These particles showed a characteristic I-H curve for single domain particle assemblies.View full abstractDownload PDF (2795K) -
Influence of the Bulk Density on the Dimensional AccuracyYuzo Mori, Naoya Ikawa, Hidetsugu Yagi, Kazuo Kanehiro1982 Volume 29 Issue 2 Pages 45-49
Published: February 25, 1982
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe influence of the packings on the dimensional accuracy of the sintered machine parts is studied. Detailed discussion covers the problems of the influence of the bulk density on the green density and the plastic strain energy. In the experiments the rubber press method which is one of the hydrostatic press methods is adopted in order to compact the powder uniformly.
The scattering of the bulk density exerts influence on the dimensioal accuracy of the sintered machine parts. The green compacts of the density 5.3g/cm3 compacted from the powder of the bulk density 2.7-3.5 g/cm3 result in the dimensional changes of 0.48-0.34% after sintering, and the green compacts having the same strain energy (W=30 kg.mm/mm3) result in the dimensional changes of 0.52-0.29% after sintering. Under the same compressive stress, as the bulk density increases, the green density increases and consequently the dimensional change decreases after sintering. In compacting the green compacts having the same density, as the bulk density increases, the plastic strain energy decreases and after sintering the dimensional change decreases.View full abstractDownload PDF (325K) -
Kenzo Hanawa, Kiyoaki Akechi, Zenshiro Hara1982 Volume 29 Issue 2 Pages 50-53
Published: February 25, 1982
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThis paper describes trials which prepare iron sheets containing large amount of graphite by powder rolling. A powder rolling machine has two φ160mm chilled rolls arranged horizontally and a powder feeding hopper with a controlling gate to feed constant amount of powder. Reduced iron powder-graphite mixtures and cast iron powder-graphite mixtures were rolled, and the rolled sheets were sintered at 1393K for 30min. The experimental results are as follows.
-Cast iron powder could be mixed with graphite more homogeneously than reduced iron powder with
graphite.
-Cast iron powder-graphite mixtures containing 2-8%C could be rolled into sheets of 0.4-0.6mm thickness, while reduced iron powder-graphite mixtures containing 2-8%C could not be rolled into sound sheets.
-The sintered sheets containing 2-8%C have tensile strength of 500-80 MPa. and it seems to be enough
for wear-resistance and sound-absorption application of the materials.View full abstractDownload PDF (2279K) -
Hisashi Suzuki, Koji Hayashi, Yasuro Taniguchi1982 Volume 29 Issue 2 Pages 54-57
Published: February 25, 1982
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe formation mechanism off-free layer(βFL) which appears near the specimen surface of WC-β(N)-Co alloys was studied. The alloys were prepared by vacuum-sintering using WC-TiC-TiN solid-solution (β(N)) powders having different compositions.
It was found that the thickness of OβFL decreased with increasing the amount of β(N) (with a fixed com-position) in the alloy, and with increasing nitrogen content in the alloy at a fixed amount of f(N) (with differ-ent compositions), and also with decreasing carbon content in the alloy. The relation, xoct1/2, wascon firmed, where x is the thickness of βFL and t is the sintering time. From these results, it was concluded that the formation of βFL was rate-controlled by diffusion process, in which nitrogen moves towards the specimen sur-face through the liquid phase during sintering in β-FL, in the same way as in WC-β-Co alloys containing TiN. The mass transfer from the surface layer to the inside of specimen was also examined.View full abstractDownload PDF (3969K) -
Hisashi Suzuki, Koji Hayashi, Hideaki Matsubara1982 Volume 29 Issue 2 Pages 58-61
Published: February 25, 1982
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe anomalous structures appearing near the specimen surface were studied for Ti(C, N)-Mo2C-Ni alloys prepared by vacuum-sintering.
It was found that surrounding structures of carbonitride particles were not observed in the surface layer (such a layer is named "surrounding structure free layer, SSFL"), and that the formation of SSFL was related to the nitrogen loss from specimen surface during sintering. The thickness increase of SSFL was restrained with the increase of sintering time, in contrast to a previous result reported by the authors on the f free layer in nitrogen contained WC-β-Co alloys. This phenomenon would be understood, considering the following fact being peculiar to this alloy system, that the solutes concentration gradient near the surface layer decreases with increasing thickness of SSFL. In addition, changes in hardness, lattice parameter of hard phases, etc., near the surface layer were discussed.View full abstractDownload PDF (1591K) -
Takeshi Sadahiro1982 Volume 29 Issue 2 Pages 62-67
Published: February 25, 1982
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSFracture toughness and chipping resistance in milling test of TiC-9TiN-9WC-9TaC-16Ni-16Mo2C alloy were investigated in relation to the carbon content and the TiN content (5-13%) of the alloy.
The results obtained are as follows.
(1) Fracture toughness of the alloy is larger than that of the TiC-Ni-Mo2C alloy and is equal to the WC-Co alloy.
(2) Carbide grain size and thickness of intermediate phase of the alloy decrease with the increase of carbon content and TiN content, while hardness and fracture toughness of the alloy increase.
(3) Fracture toughness of the TiC base alloy correlates to both the crack resistance and the fracture tough-ness determined by the indentation method.
(4) Chipping resistance of the alloy in milling test depends on its fracture toughness.View full abstractDownload PDF (1449K)
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