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Volume 12 (1965)
- Issue 6 Pages 219-
- Issue 5 Pages 183-
- Issue 4 Pages 139-
- Issue 3 Pages 93-
- Issue 2 Pages 55-
- Issue 1 Pages 7-
Volume 12, Issue 5
Displaying 1-3 of 3 articles from this issue
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Toyoji Hirata1965 Volume 12 Issue 5 Pages 183-186
Published: October 25, 1965
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSMuch of coarse aluminium powder for thermit reaction has been produced by the cross jet method. But the fine powder is less produced thereby. Recently, demands for fine aluminium powder are increasing gradually and it is urgently requested that vertical atomization for molten aluminium is developed and brought to industrialization, because the vertical atomization is said to be preferable for manufacturing fine metal powder.
This experiment was carried out to investigate the fundamental behavior of vertical atomization, comparing it with the conventional cross jet method. The results derived from this experiment are as follows.
1) It is fully possible that the minus 200mesh fine aluminium powder is produced more than 50 percent of the whole atomized powder by vertical atomization. On the other hand it is not easy to take out minus 200mesh fine powder more than 30 percent by cross jet mothod.
2) In order to obtain a given distribution, the vertical atomization requires much lower air pressure than the cross jet method.
3) In vertical atomizing the air jet forms a closed air curtain beneath the nozzle tip and a back pressure takes place. It prevents the settling of the molten aluminium. Then the unit manufacturing capacity of the vertical atomization is 50-60 percent of that of the cross jet method.
4) The disintegration by the cross jet is almost impossible, when sprayed by air compressed at a pressure lower than 2kg/cm2.
5) In the case of the vertical atomization by using a small bore strainer, the molten aluminium is apt to solidify in the strainer to the cooling by the air jet.View full abstractDownload PDF (1363K) -
Shinroku Saito, Shigeyuki Somiya, Koichi Kato1965 Volume 12 Issue 5 Pages 187-198
Published: October 25, 1965
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSInfuences of binders, grain sizes, gap gradings, forming methods, sintering temperature, sintering atmospheres, etc. on properties of both green and sintered silicon nitride bodies were determined. The binders used in this study were C.M.C., Maxelon M (Wax Emulsion), polyethylen glycol 4000, camphor, ethylsilicate, colloidal silica sodium silicate, aluminum hydroxide, Monophix (aluminum phosphate solution), colloidal alumina, and bentonite. One sample was moulded without binders using ageing method.
The results are as follows :
(1) C.M.C. and aluminum bearing materials were good for binders of green bodies of silicon nitride. The maximum modulus of rapture was 14.0kg/cm2 in the case of C.M.C.
(2) The modulus of rupture of sintered body increased when alumina bearing binders such as Al(OH) 3 was used. The maximum modulus of rupture was 246kg/cm2.
(3) Ageing of silicon nitride powder on modulus of rupture was effective. The maximum modulus of rupture was 202kg/cm2. The longer the ageing time, the higher the maximum modulus was.
(4) Better results were obtained by using the dry mixing of the binders such as ethylsilicate, colloidal alumina, and collidal silica than using the wet mixing. The modulus of rupture increased about 30-40% by using the dry mixing. (5) In general, the modulus of rupture of 60 mesh grain bodies after sintering in NH 3 atmo-sphere was higher than that of 200 mesh grain bodies. The maximum modulus of rupture of the 60 mesh grain body was the ageing sample of 202kg/cm2, and for 200 mesh grain body was 167kg/cm2, Al(OH) 3 binder sample.
(6) In the case of binders such as C.M.C. and Al(OH) 3, better results were obtained at temperatures higher than 1, 420°C for sintering, but in the case of bentonite and non-addition of ageing sample, 1, 420°C was better the other temperatures.
(7) In the case of Al(OH) 3, bentonite and non-addition, N 2 atmosphere was better than NH 3 for sintering. The modulus of rapture was increased 1.5 to 2 times.
(8) The expansion which have been occurred at the sintering was less than 2%.View full abstractDownload PDF (676K) -
Akio Koyano1965 Volume 12 Issue 5 Pages 199-205
Published: October 25, 1965
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSTo improve the mechanical Q of lead zirconate-titanate: Pb(Zr-Ti)O3 ceramics, several effects of additions in small quantity were investigated. As additions, ZnO ; Al2O3 In2O3, Ga2O3 ; NaOH, KOH and RbOH are selected in consideration of their ionic radii and valencies. The results obtained are as follows :
(1) The fine grain structure is obtained by and of these additions except RbOH and the high density is attained in all cases.
(2) The mechanical Q is extremely improved within the limit of the additions of 0.5-1mol%.
(3) Zn2+, Al3+, In3+ and Ga3+ seem to replace the Zr4+-Ti4+ ions and Na+, K and Rb2+ the Pb2+-Sr2++ ions, viewed from the amount of PbO absorption and ionic radii.
(4) An addition of In2O3, ZnO or NaOH sifts the morphotropic phase boundary toward the Ti excess site to some extent.
(5) Assuming that these metallic ions replaced Pb2+-Sr2+ or Zn4+-Ti4+ sites create an oxygenvacancy which is frozen at room temperature, this vacancy will induce an anisotropy. Consequently, it seems that by this induced anisotropy a motion of 90° wall is prevented, and mechanical Q is reduced.View full abstractDownload PDF (352K)
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