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Volume 30, Issue 4
Displaying 1-7 of 7 articles from this issue
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[in Japanese]1983 Volume 30 Issue 4 Pages 133-139
Published: June 25, 1983
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (2930K) -
Tadahiko Watanabe1983 Volume 30 Issue 4 Pages 140-145
Published: June 25, 1983
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSTiB2-5%TaB2-CoB and TiB2-5%W2B5-1%CoB materials have higher transverse rupture strength, hardness and density than those of TiB2-1%CoB materials. The strengthening mechanism of both types materials, TiB2-5%TaB2-1%CoB and TiB2-5%W2B5-1%CoB, has been discussed. The higher transverse rupture strength of the both materials has been caused mainly by suppressing grain growth of TiB2 with the solid solution between TiB2 and TaB2, or between TiB2 and W2B5, and caused secondarily by the lattice strain of TiB2, and reduction of residual pores.View full abstractDownload PDF (4429K) -
Tohru Kohno, Yoshio Nishino1983 Volume 30 Issue 4 Pages 146-151
Published: June 25, 1983
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSEffects of the addition of phosphorus (0.2-0.8%) to Cu-9% Sn compacts which was standard composition of conventional bronze oil impregnated sintered bearings were examined during sintering process. The bearing running test was also carried out under the heavy load condition for Cu-base oil impregnated bearings on Cu-9%Sn-0.4%P bearing.
The results obtained were as follows;
1) By the addition of phosphorus, Cu-Sn compacts were remarkably strengthened. For example, the radial crushing strength of the compact added 0.4% phosphorus, pressed at 2 t/cm2 and sintered at 700°C for 30 min., was 11 kg/mm2 higher than that of the non-phosphorus compact.
2) On the case of addition of phosphorus above 0.4%, the swelling phenomena during sintering process, which occur above peritectic temperature (798°C) in ordinary mixed Cu-Sn powder compacts were not observed. The reason was seemed that owing to the addition of phosphorus alloying of Sn had progressed sufficiently through the sintering below peritectic temperature.
3) Sinterability of mixed Cu-Sn powder compacts was extremely enhanced by the addition of phosphorus. With the progress of sintering, large pores became larger, but on the contrary small pores became smaller and gradually disappeared. So, the oil impregnated sintered Cu-Sn-P bearings having large size pores and high strength can be produced by selecting the proper sintering conditions.
4) In the running test, Cu-9%Sn-0.4%P bearings showed excellent bearing performance even under the heavy load condition (P=20 kg/cm2, N=4, 000 rpm, PV=2, 000 kg/cm2m/min) in which the oil impregnated pores were closed by the plastic flow of the rubbing surface in the conventional sintered Cu-9%Sn bearings.View full abstractDownload PDF (5847K) -
Tohru Kohno, Yoshio Nishino1983 Volume 30 Issue 4 Pages 152-155
Published: June 25, 1983
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSA manufacture of Cu-Sn-P-MoS2 type oil impregnated sintered bearing for high speed revolution applications was tried and the following results were obtained.
1) To obtaine a satisfactory yield of MoS2 added, sintering under about 750°C is necessary even in the case of large MoS2 particles (average particle size; 6μm) used in this experiment.
2) In the sintering of Cu-Sn-P compacts added MoS2, Cu-P-Mo-S compounds are formed at the surface of MoS2 particles in the range of 700-750°C. As the volume of the surface layer of MoS2 particles increases during the formation of these compounds, the adhesion between MoS2 particles and the matrix can be well improved.
It can be expected in this Cu-Sn-P-MoS2 type bearing that the thin layer of the reaction product formed around the MoS2 particles above mentioned acts as a kind of binder between the matrix and the MoS2 particles, thus prevents the solid lubricant (MoS2) from mixing into the lubricant oil under hydrodynamic condition of high speed revolutions; such an excessive mixing in general worsens the running performance under hydrodynamic lubrication of the bearing.View full abstractDownload PDF (4723K) -
Control of Size, Quantity and Distribution of CarbidesKanji Notomi, Seiya Furuta, Nobuyasu Kawai1983 Volume 30 Issue 4 Pages 156-161
Published: June 25, 1983
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSOur results show that by changing the size and the content of high chromium iron powder, carbides in roll steel can be easily controlled. It is well known that carbides as well as matrix play an important role in roll steel: A new P/M process, called "The Pre-mix Process", developed by KOBE STEEL, LTD., provides an easy way to control the properties of carbides such as size, content and morphology. In "The Pre-mix Process", high chromium iron powder is mixed with roll iron powder and then HIP'ed to a full density. During HIP'ing, high chromium iron powder changes into massive carbides whose size is almost the same as that of powder particles.View full abstractDownload PDF (4417K) -
Kanji Notomi, Seiya Furuta, Akira Shimamoto, Nobuyasu Kawai1983 Volume 30 Issue 4 Pages 162-166
Published: June 25, 1983
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSSteel powders containing 1.5%C-12%Cr have been produced by gas-atomization, and their fully densified P/M steel billets have been made by hot isostatic pressing.
Microstructures and mechanical properties of the P/M steel have been investigated in comparison with the conventional high C-high Cr cold die steel (1.5%C-12%Cr).
In the P/M steel, fine carbides are uniformly distributed, whereas in the conventional steels, large-sized carbides are distributed among fine carbides.
Mechanical properties of the P/M steel are as follows:
(1) Bend strength, impact strength and wear resistance under unlubricated condition of the P/M steel are superior to those of the conventional steel.
(2) Compressive yield strength of the P/M steel is equivalent to that of the conventional steel.
(3) Fracture toughness and wear resistance under lubricated condition of the P/M steel are inferior to those of the conventional steel.View full abstractDownload PDF (4668K) -
Kenzo Hanawa, Kiyoaki Akechi, Takeo Nakagawa1983 Volume 30 Issue 4 Pages 167-170
Published: June 25, 1983
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThis paper describes improvement of the strength of sintered products made from cast iron powder in combination with dimensional precision. Various mixtures consisting of cast iron powder, reduced iron powder, and partially pre-alloyed copper-iron powder were compacted at 800 MPa and sintered at 1423 K for 0.5-20 h in hydrogen atmosphere. The results shows that the tensile strength of 890 MPa can be achieved by the sintering of cast iron powder mixed with iron powder. It is also shown that by substituting partially pre-alloyed copper-iron powder for normal reduced iron powder, dimensional precision can be controlled. Consequently, at a given strength level, it is possible to achieve considerable saving of expensive alloying elements by using cast iron powder.View full abstractDownload PDF (1545K)
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