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Volume 31, Issue 5
Displaying 1-6 of 6 articles from this issue
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Toru Morimoto, Masahito Fujita1984 Volume 31 Issue 5 Pages 155-158
Published: July 25, 1984
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSA calculation of the air flow resistance relating to the pore size and the porosity in porous sintered sheets was carried out using D'Arcy's equation, and a design and a construction of the flow resistance measuring apparatus for the sheets were practiced.
Then the relation between the sound absorption character of high porous sintered aluminum base sound absorbents and the frequency of sound was cleared by measuring the sound absorption. coefficient with the vertical sound absorption method and the reverberant sound absorption method.
It was found that the porosity from 37% to 40% is the best for sound absorption in conditions of the frequencies from 500 to 2000 Hz of sound and the air gap over 50 mm.View full abstractDownload PDF (264K) -
Toru Morimoto, Toshio Hagihara1984 Volume 31 Issue 5 Pages 159-162
Published: July 25, 1984
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThis report is tried to clarify the sound absorption character of porous sintered aluminum base sheets by vertical sound absorption method with the following samples; (1) a perforated aluminum metal sheets, (2) the perforated aluminum metal sheet having porous sintered aluminum or glasswool, (3) the porous sintered aluminum base sheets, and (4) a pore-simplified sintered aluminum base sheet prepared by paraffine treatment.
From the above experiments, it can be said that the porous sintered aluminum base material has a three-dimentional structure, therefore the sound absorption curve is similar to of the perforated metal, but the former has smoother and wider sound absorption curves against the frequency than the latter.
An effect of the air gap behind the porous sintered aluminum base sheet on the sound absorption was also examined. It was found that, in order to get a more good sound absorption curve in wider frequencies, it is important to set the sheet in the apparatus with some inclined air gaps against the sound waves.View full abstractDownload PDF (269K) -
Tadatoshi Honda1984 Volume 31 Issue 5 Pages 163-168
Published: July 25, 1984
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe present investigation was carried out to clarify the influence of internal and external notch effects and effective cross section ratio on the fatigue strength of sintered irons prepared from fine and coarse particle sizes.
The results obtained were as follows:
(1) The internal notch factor of pore (βp) in specimens prepared from fine and coarse particle sizes was in the range 1.28 to 3.81.
Values of βp increased considerably as the sintered density and sintering time decreased, and as the powder particle size increased.
(2) The external notch factor (βn) of those specimens was in the range 1.01 to 1.47. Values of βn increased as the sintered density and sintering time increased, and as the powder particle size decreased.
In specimens having the same density, the external notch factors tended to be higher for the lower internal notch factors.
(3) The effective cross section ratio of those specimens decreased with the decrease in sintered densities and with the increase in powder particle sizes, resulting in the reduction of those fatigue strengths.View full abstractDownload PDF (1722K) -
Hideki Taguchi, Yuzuru Takahashi, Masahiko Shimada, Mitsue Koizumi1984 Volume 31 Issue 5 Pages 169-171
Published: July 25, 1984
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSMagnetic and electrical properties of (La1-xMx) CoO3 (M: Ca2+, Sr2+ and Ba2+ ions) are strongly influenced by the substitution by the alkaline earth metal ion. It is found that the distance Co-O and the content of low spin state Co ?? ion affect on the magnetic interaction and the overlap of electron.View full abstractDownload PDF (185K) -
Naoichi Yamamoto, Masayoshi Horibe, Shinji Kawano, Shin-nosuke Higashi1984 Volume 31 Issue 5 Pages 172-176
Published: July 25, 1984
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSFormation and stability of the transition metal-substituted cobaltites in alkaline solution were investigated with hydrothermal technique. Two kinds of cobaltites, Co3O4 and ZnCo2O4 were obtained throughout whole reaction temperature range and MnCo2O4 was obtained below 110°C or above 550°C. Between these temperatures MnCo2O4 dispropotionated to spinel and other compounds. FeCo2O4 was also unstable and disproportionated to Fe-poor cobaltite and Co-poor cobalte ferrite in alkaline solution. Other kinds of transition metal-substituted cobaltite were not obtained in these experimental conditions.View full abstractDownload PDF (280K) -
Hideo Torii, Hideyuki Okinaka, Toshihiko Miyazawa, Hiromichi Mitsuda1984 Volume 31 Issue 5 Pages 177-180
Published: July 25, 1984
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThough a partially stabilized zirconia ceramic shows high resistance to mechanical stress, it has a drawback that the resistance becomes remarkably small when it is held at 200-300°C.
As a result of our investigation for the deterioration mechanism of the ceramic, it was found that the deterioration is due to the great expansion of its volume, which is caused by the martensitic transformation of tetragonal phase to monoclinic symmetry, and it has become apparent that the sizes of tetragonal crystallites which exist in tetragonal grains in the ceramic and the degrees of their strains determine whether the deterioration occurs or not.View full abstractDownload PDF (2444K)
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