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Volume 7 (1960)
- Issue 6 Pages 255-
- Issue 5 Pages 197-
- Issue 4 Pages 149-
- Issue 3 Pages 99-
- Issue 2 Pages 35-
- Issue 1 Pages 1-
Volume 7, Issue 2
Displaying 1-4 of 4 articles from this issue
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Yasumasa Goto, Toshio Takada1960 Volume 7 Issue 2 Pages 35-40
Published: April 25, 1960
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe equilibrium of the system BaO-Fe2O3 has been studied by ordinary mineralographic methods. In some of the specimens of this system, the dissociation of Fe2O3 has been observed, and hence in such cases, the experiments were conducted under 1 atm. pressure of oxygen.
The results obtained in the present studies are summarized in Fig. 1. The existence of three compounds BaO⋅6Fe2O3, BaO⋅Fe2O3 and 2BaO-Fe2O3 was confirmed. The two binary eutectic reactions, Liquid ?? BaO.6Fe2O3+BaO⋅Fe2O3 at 1370°C and Liquid ?? BaO⋅Fe2O3+2BaO⋅Fe2O3 at 1330°C ware observed at the composition of 60.0 mole% and 41.2 mole% Fe2O3 respectively.
BaO.6Fe2O3 (85.7mole% Fe2O3) forms a solid solution by the dissolution of BaO⋅Fe2O3. The BaO: Fe2O3 ratio of the solid solution was 18.2: 81.8 mole at 1350°C and 16.7: 83.3 mole at 800°C, but the solubility of Fe2O3 in this phase was not observed. The solubility range of BaO.Fe2O3 phase is very narrow and the solubility of BaO⋅Fe2O3 in 2BaO⋅Fe2O3 was not observed. The compound BaO⋅6Fe2O3 is a hexagonal lattice, a =5.877, c=23.02Å, BaO⋅Fe2O3 a tetragonal lattice, a=6.02, c=9.45Å, and 2BaO⋅Fe2O3 a cubic lattice, a=8.07Å.View full abstractDownload PDF (1898K) -
Minoru Ozasa1960 Volume 7 Issue 2 Pages 41-48
Published: April 25, 1960
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe recrystallization process in tungsten wire with different doping materials was studied under electron and optical microscopes. Drawn tungsten wires consist of long fibres, each of which is a bunch of sub-fibres 0.1 to 1μ in diameter. Before recrystallization takes place by heat treatment, the growth of sub-fibres starts. But when the doping effect is prominent, it does not allow sub-fibres to grow over 1μ in diameter, and the length of over several tens of microns remains, at 2, 400°K. At about 2, 800°K. a huge crystal grows directly out of sub-fibres and coexists with remaining sub-fibres and the boundary between the huge crystal and such remaining sub-fibres has steps here and there, height of the step being width of the sub-fibre.
In the meantime, another huge crystal grows into such remaining sub-fibres. After the recrystallization process is over, the very stable sub-fibre boundaries facing the former huge crystal form the boundary between the former and the latter huge crystals. In the resulting structure, therefore, large grains interpenetrate deep into the neighbouring grains in the axial direction of the wire. The wire having such a structure is suitable for practical uses, being non-sag at high temperatures and free from brittleness at room temperatures.View full abstractDownload PDF (8373K) -
Kenzo HIJIKATA, Yuichi TAJIMA1960 Volume 7 Issue 2 Pages 49-57
Published: April 25, 1960
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe sintering process of plain Iron compacts and Iron-Carbon compacts was investigated by thermal balance and dilatometer during thermal cycle. The effects of moisture contents in hydrogen atmosphere were observed ; A atmosphere with 1.7-1.9 mg/L moisture content, B with 0.2-0.3 mg/L. The Mechanical and physical properties of sintered compacts were measured. The results were as follows.
1) Dimensional change
The specimens containing graphite showed lower shrinkage than plain iron. The shrinkage was greater with A atmosphere than with B atmosphere.
2) Weight change
The weight continued to decrease up to about 900°C, owing to degassing, desorption of moisture and reduction of oxide on the surface of iron powder. Above that temperature, the gassification of graphite by hydrogen was observed.
3) Mechanical properties
Higher strength was obtained for specimens sintered in A atmosphere and their graphite contents were as high as 1%.
4) Carburization
The carburization rate was greatly influenced by the moisture content in hydrogen. In the A atmosphere, the formation of carbide was pronounced, with decarburized layer as thick as 1.6mm. On the contrary, in the B atmosphere, the decarburized layer was very thin and much carbon was left uncombined.View full abstractDownload PDF (1706K) -
Henry H. Hausner1960 Volume 7 Issue 2 Pages 58-72
Published: April 25, 1960
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSA mass of metal powder is characterized by powder particles and the voids between these particles. The variables of the porosity in metal powder compacts are discussed and analyzed, and the rate of densification during sintering is expressed in an equation consisting exclusively of various functions of porosity. The changes of porosity during the sintering process are discussed. It is shown that the differences between sintering of pressure-compacted, deformed powder particles and undeformed, loose powders are due to the variation in the pore structure; the rate of densification during sintering of undeformed powder particles is considerably greater than that of particles deformed by pressure. Pores in metal powder compacts affect the grain boundary movement, as solid inclusions do. The bond between a grain boundary and a void depends on the pore shape. Before spheroidization of the voids, the grain boundaries stick to the voids; after spheroidization, the grain boundaries move away. Oriented porosity may cause oriented grain structure.View full abstractDownload PDF (2007K)
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