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Volume 31, Issue 1
Displaying 1-6 of 6 articles from this issue
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Hideyuki Tsuda, Junichi Hojo, Akio Kato1984 Volume 31 Issue 1 Pages 1-7
Published: January 25, 1984
Released on J-STAGE: July 12, 2010
JOURNAL OPEN ACCESSSintering behavior of binary mixture of SiC powders was investigated by using powders having average particle sizes d=0.01-0.02, μ and 0.04-0.45μ. Binary powder mixing had little effect on the green density of compact, but increased the density of sintered body, fired at 2050°C for 30 min, at the coarse powder fraction around 85%. For example, a powder mixture of 15% of fine powder having d=0.01μ and 85% of coarse powder having d=0.08 μ gave relative density of 98%, against the component fine and coarse powders gave relative density of 90% and 57%, respectively. Sinterability of binary mixture of 15% fine-85% coarse powders both of which were produced by CVD method increased with increase of particle size ratio and became constant above the ratio ≈8. This enhanced sinterability may be due to a particle rearrangement effect and a detardation of growth of coarse particles by the presence of fine powders in the course of heating.View full abstractDownload PDF (1678K) -
Jian-Ping Dai, Xi-Wen Lai1984 Volume 31 Issue 1 Pages 8-13
Published: January 25, 1984
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSInfluential factor was investigated during determining apparent density. The difference of apparent densities were obtained from different sampling amounts of powder. Authors were able to explain this phenomenon by means of the potential energy of powder particles from funnel to cup of the apparatus and the tapped powder in the cup because of striking action of falling powder particles overmuch to the cup.View full abstractDownload PDF (1147K) -
Hisashi Suzuki, Koji Hayashi, Kei Tokumoto, Yoshihiro Onomura1984 Volume 31 Issue 1 Pages 14-19
Published: January 25, 1984
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSRoom temperature transverse-rupture strength and microstructure of Si3N4-MgO compacts sintered in nitrogen were mainly investigated as a function of sintering temperature and MgO content (0-30%).
The strength reached a maximum, when compacts containing 5 -10%MgO were sintered in nitrogen of l00kPa at 1973K. The Mg2SiO4 phase as the binder of Si3N4 particles was observed to have an identical crystallographic orientation in a wide region (named as a domain). The shrinkage pore acting as a fracture source was found to lie on the domain boundaries. The result of fractography showed that, even in the compact free from defects as fracture sources, the strength would not exceed the value of about 0.9GPa.View full abstractDownload PDF (5289K) -
Hisashi Suzuki, Hideaki Matsubara, Takeshi Saitoh1984 Volume 31 Issue 1 Pages 20-24
Published: January 25, 1984
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe mechanical properties of TiC0.7N0.3- and TiC0.5N0.5-Mo2C-Ni alloys sintered in nitrogen were studied at room temperature as a function of microstructure, nitrogen pressure (PN2), etc.
It was found that transverse-rupture strength and hardness varied in each alloy with changing PN2. As for the strength, the maximum value was obtained at PN2 up to 0.2kPa and at 3kPa in TiC0.7N0.3 and TiC0.5N0.5 alloys, respectively. The strength level was higher in the former alloy irrespective of PN2. These results could be understood by considering the fact that pores acting as fracture source were apt to form in each alloy during sintering in nitrogen, but pore size was always smaller in TiC0.7N0.3 alloy; pore size in each alloy was minimized at the above PN2, where each carbonitride was found to be stabilized under these pressures.View full abstractDownload PDF (2935K) -
Densification Caused by Liquid PhaseMasao Morishita, Hiroshi Nagai, Keiichiro Shoji1984 Volume 31 Issue 1 Pages 25-30
Published: January 25, 1984
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSSintering behavior of prealloyed powder of nickel base superalloy TN-100 was investigated by dilatometry and differential thermal analysis.
The results obtained are as follows:
(1) Rapid densification occurred above 1513K, though sintering rate was very slow below 1493K.
(2) It was ascertained that the rapid densification above 1513K was caused by a small amount of liquid phase, which was originated by two kinds of incipient meltings in the temperature range 1498-1523K and 1523-i548K. Macroscopic melting of the compact occurred at the temperature above 1553K.View full abstractDownload PDF (3583K) -
Sachio Oki, Toshiyuki Atsumi, Toshiyuki Akiyama, Keiichiro Shoji1984 Volume 31 Issue 1 Pages 31-38
Published: January 25, 1984
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSA study has been made on the mechanical properties of sintered Cr-Mo steels (Fe-l o%Cr-0.2o%Mo-0.35%C) containing metallic Mo, Mo carbide, or ferro-Mo powders as an alloying additive. The static tensile and fatigue properties were compared with those of Cr-Mo steel made from prealloyed atomized powders.
The microstructure of prealloyed specimens was observed to be relatively homogeneous, whereas the premixed specimens showed a heterogeneous microstructure caused by Mo segregation.
The effect of microstructural heterogeneity, caused by a different way of Mo addition, on static tensile properties was scarcely distinguished. On the other hand, fatigue strength was affected by these microstructures.
Abrupt change in hardness of segregated area led to a decrease in fatigue strength. However, the fatigue strength was improved by the presence of the microstructural heterogeneity where gradual changes in hardness existed.View full abstractDownload PDF (7185K)
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