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Volume 28, Issue 8
Displaying 1-6 of 6 articles from this issue
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Kazutaka Makino1981 Volume 28 Issue 8 Pages 269-275
Published: November 25, 1981
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIn this paper, the particle packing structures of various industrial powders, especially the estimation model of their radial distribution function was presented by the introduction of a new conception "particle density original function" and the validity was discussed.
As a result of it, it is pointed out that the new conception indicates a new, effective and statistical stand-point to elucidate the particle packing structure of powder particle system, in which component particles make a random movement or they are in stationary state, and has a high applicability to various industrial powders.View full abstractDownload PDF (577K) -
Kazutaka Makino1981 Volume 28 Issue 8 Pages 276-281
Published: November 25, 1981
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIn this paper, a new statistical viewpoint which represents the particle packing structure, particularly the radial distribution function, of powder bed was proposed and its validity was examined, numerically.
1) This method is built up on the fundamental standpoint that the radial distribution function of randomly packed particle system can be regarded as a stationary wave of the particle density around a specified particle.
2) By introducing the conception of particle density original wave function on the viewpoint of 1), it is described that the radial distribution function of randomly packed particle system is given by a stationary wave produced by the mutual interference between reflected wave from the specified particle and the particle density original function itself.
3) The validity of this viewpoint was verified by using the results of the conventional calculation and also of computer aided simulation.View full abstractDownload PDF (409K) -
Naoichi Yamamoto, Masayoshi Horibe, Shinnosuke Higashi1981 Volume 28 Issue 8 Pages 282-285
Published: November 25, 1981
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSExistence of the fourth polymorph of MnOOH was affirmed. The compound was synthsized by bubbling air into the suspension of amorphous MnO2 at room temperature, where pH value was around 6. The compound was an antiferromagnet (TN=58.5K) and dehydrogenized to β-MnO2 at 270°C.View full abstractDownload PDF (1139K) -
Takeshi Sadahiro1981 Volume 28 Issue 8 Pages 286-290
Published: November 25, 1981
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSFracture toughness by indentation in WC-Co alloys containing addition carbides was determined on the basis of the average distance between the surface crack tips measured on the surface along the directions of Vickers indentation diagonals. Results obtained are as follows. (1) The fracture toughness by indentation agrees well with that obtained by fracture testing. The fracture toughness determination by indentation will be useful because of a simple technique for the rapid evaluation of toughness on small samples.
(2) Brittleness parameter, i.e., the hardness fracture toughness ratio which has been proposed for the evaluation of the characteristics of materials, can be applied to cemented carbides. The fracture toughness by indentation and the crack resistance, which are related to the fracture toughness by fracture testing, would be employed instead of the fracture toughness in brittleness parameter.View full abstractDownload PDF (311K) -
Koji Hayashi, Naomi Namiki, Hisashi Suzuki1981 Volume 28 Issue 8 Pages 291-294
Published: November 25, 1981
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe high temperature deformation behavior of WC-(1020)%Co cemented carbides was studied as a function of carbide grain size (1.6-6.5 μm) and carbon content by means of three-point bending tests at 873-1273 K.
It was found that, at a temperature as low as 873 K, the deformation was suppressed as carbide grain size and carbon content decreased; but, at 1273 K, it was inclined to be suppressed as grain size increased and carbon content decreased, with some exceptional cases. It was shown that the transverse-rupture strength at 1273 K reached a maximum at the grain size from 4 to 5um, the exact value being varied according to the carbon content. These results would be explained by considering the dynamic recovery of cemented carbides, which is a function of carbide grain size, carbon content, etc.View full abstractDownload PDF (280K) -
Tadatoshi Honda1981 Volume 28 Issue 8 Pages 295-301
Published: November 25, 1981
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIt is the purpose of this study to investigate the influence of type and quantity of lubricants on the dimensional change, tensile and fatigue strengths of electrolytic iron powder compacts.
The results obtained were as follows:
(1) The dimensional changes of Fe compatcs containing Ca-and Mg-stearates showed a little shrinkage with higher lubricant contents at low compacting pressures, but for high applied pressures, a tendency to considerably expand as increasing lubricant contents from 1.0 to 1.5 wt%.
(2) The tensile strengths of Fe compacts containing 0.5 wt% lubricants, increased with higher sintered densities as well as in the case of die-wall lubricant. For 1.5 wt% lubricant contents, they depended upon the types of lubricant, specially those of the specimens containing Ca-, Mg- and Co-stearates remarkably decreased at sintered density above 6.7 Mg/m3.
(3) The fatigue strengths of Fe compacts containing several lubricants were due to the type and quantity of lubricants. In particular, those of Fe compacts containing 0.5 wt% Mg- and 1.5 wt% Ca-stearates considerably decreased in comparison with other lubricants.View full abstractDownload PDF (4207K)
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