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Volume 22, Issue 6
Displaying 1-5 of 5 articles from this issue
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Case of Axi-symmetric CompactingKunio Okimoto, Moriya Ôyane, Susumu Shima1975 Volume 22 Issue 6 Pages 177-184
Published: October 05, 1975
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSVarious practical consolidation processes such as closed die compaction, hydrostatic compaction and dry rubber press are performed, and relations between stresses and densities are investigated. The stresses required in these compacting processes are compared with the yield stress and fracture stress in uniaxial compression test of green compacts.
For a stress state such that σ2=σ3, the following equation is obtained, which gives a relation between stress and density in compacting process:
?? (a=g1(γ), b=g2(γ);both are the function of γ.)
where σ1, σ2, σ3 are the principal stresses and γ the relative density.View full abstractDownload PDF (545K) -
Kunio Okimoto, Moriya Ôyane, Susumu Shima1975 Volume 22 Issue 6 Pages 185-191
Published: October 05, 1975
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSFracture behaviour of green compacts is investigated under an axi-symmetrical stress condition such that σ2=σ3 in three principal stresses σ1, σ2 and σ3, that is, a uniaxial compression and a compression under hydrostatic pressure.
Relations between σ1 and σ2 at fracture point, and between σ2 and fracture strain ε1f are investigated. The former relation is represented in Rendulic stress plane, where σ2=σ3, by using a parameter γ of relative density. The curves show a fracture condition for green compacts.View full abstractDownload PDF (2538K) -
Hisashi Suzuki, Teruyoshi Tanase, Fumio Nakayama1975 Volume 22 Issue 6 Pages 192-197
Published: October 05, 1975
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThis investigation was undertaken to clarify the mechanism of micropore-formation in WC-Co alloys, from the viewpoint that pores would be resulted from coarse Co particles which pre-existed in (WC+Co) mixture. High carbon two-phase WC-Co alloys with about 10 and 20% Co were in vacuum sintered under various conditions, using usually ball-milled mixtures in which some amounts of coarse Co particles were intermixed for a model-experiment, or from which pre-existed coarse Co particles were removed or not.
Results obtained were as follows:1) In case of the low temperature sintering including solid-phase sintering, coarse Co particles in the mixture became Co pools and changed into pores as sintering time increased. In case of the high temperature sintering, those Co pools tended to change rapidly in pores, when the Co content in the alloy was low. 2) Thus, the structural defects such as Co pools and pores were confirmed to be closely related to each other. Pores above mentioned didn't develope in the alloys, for instance, with high Co contents because of the facility of viscous flow of the matrix. 3) The above results in model-experiments were considered to be available also in the usual WC-10% Co alloy. Because, the removal of coarse Co particles which pre-existed in the ball-milled mixture resulted in disappearence of the pores, the dimensions of which corresponded to those of removed Co particles, leading to a sharp increase in the strength of alloys.View full abstractDownload PDF (3571K) -
Iwao Matsuyama, Takanobu Noro, Shigeru Jômura1975 Volume 22 Issue 6 Pages 198-201
Published: October 05, 1975
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSGrain growth of PLZT was investigated as a function of the hot-pressing parameters of temperature, time and pressure. The selected conditions are; temperature range from 1100 to 1250°C, time range from 120 to1440 minutes and pressure range from 0 to 350kg/cm2.
The results indicated that the grain growth depends upon the temperature and time, but does not on the pressure. Grain growth for 8/65/35(La/Zr/Ti) PLZT was expressed as follows; D3=34×10texp(-ΔH/RT), where D is the average grain size in μm unit, t the time in min. T the absolute temperature and ΔH an activation energy. The activation energy of 78 kcal/mol was calculated.View full abstractDownload PDF (298K) -
Osamu Yamaguchi, Hichiro Ômaki, Kiyoshi Shimizu1975 Volume 22 Issue 6 Pages 202-204
Published: October 05, 1975
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSAs a raw material for the production of spinel (MgAl2O4) at low temperature, mixed hydroxides were prepared by the simultaneous hydrolysis of magnesium and aluminum alkoxides. These hydroxides were identified as a mixture of 2 Mg(OH)2-Al(OH)3 and boemite gel AlO(OH) and were converted to spinel below 1000°C. The formation mechanism of spinel from these hydroxides was examined by means of X-ray diffraction and thermal analysis. The lattice constant of spinel obtained by heating these hydroxides at 1400°C for 3 hr was 8.088 Å.View full abstractDownload PDF (146K)
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