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Volume 17, Issue 3
Displaying 1-4 of 4 articles from this issue
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Kiyoshi Tamura, Tooru Takeda1970 Volume 17 Issue 3 Pages 97-101
Published: September 25, 1970
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIn an attempt to obtain a high density Monel alloy by a single pressing and sintering process, sintering of the mixtures of master alloy and nickel powder was discussed, and their pressing and sintering characteristics were compared with those of the mixture of nickel and copper elemental powders and also of the pre-alloyed powder. The result was summarized as follows;
1) Green compacts fabricated from the mixture of master alloy and nickel powder showed a high strength. For example, transverse rupture strength of 30Ni-70 (50Ni-50Cu) powder compact pressed at 5t/cm2 was 4.0kg/mm2.
2) Pores created in the side of the master alloy during sintering decreased considerably by the use of 50Ni-50Cu alloy instead of 40Ni-6OCu alloy. This indicates that the concentration of the copper in the master alloy should be less than 50 percent.
3) By using 50Ni-50Cu alloy powder, the compact pressed at 6t/cm2 and sintered at 1200°C for 120 min showed the density of 8.55g/cc, and the shrinkage of 3.4 percent.
4) The sintered alloy with the density of 8.55g/cc showed the tensile strength of 36.7kg/mm2 and the elongation of 34.0 percent.View full abstractDownload PDF (3377K) -
Takao Kawakita, Sukeaki Kabayama, Kenya Motoyoshi1970 Volume 17 Issue 3 Pages 102-107
Published: September 25, 1970
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe authors formerly reported the results of experiments on the fundamentals of the manufacturing process and the properties of the sintered chromium steel in the system Fe-Cr-C.
In order to investigate the effect of alloying element on certain properties of sintered chromium steel, 1 and 3 wt% of four representative alloying elements, i.e. Ni, Mn, Mo and Si were added to sintered chromiun steel (Fe-Cr-C) made from σ-phase powder, which, in the previous experiment, had being found to be best for adding Cr. Ferro-alloy powders were used as sources of Mn, Mo, Si and carbonyl powder as Ni. Mixtures of iron powder, σ-phase powder, alloying element-containing powder and carbon powder were compacted at 5 t/cm2, presintered for 1 hr at 750°C and sintered for 1 hr at 1250°C. The results obtained are as follows.
(1) In the Fe-1.5% Cr-0.5% C system, the sintered densities were from 7.2 to 7.55g/cm3.The microstructures, except those to which 3%Mn had been added, were homogenized ferritic and pearlitic. Addition of the alloying elements increased the tensile strength of the sintered compacts. The strengthening effect of the alloying elements was in the order of Si, Mn, Mo and Ni, in good agreement with that of the solid-solution strengthning of ferrite. The microstructures containing 3% Mn was martensitic.
(2) In the Fe-5.0% Cr-0.5% C system, the sintered densities were from 7.25 to 7.50g/cm3, with their microstructures, except those to which Si had been added, being homogenized martensitic and bainite. The tensile strength of the sintered compact showed 121 and 132kg/mm2 for 1 and 3g%Ni additions respectively. The microstructures of the specimens containing Si were ferritic and pearlitic.View full abstractDownload PDF (6155K) -
Katsutoshi Komeya, Hiroshi Inoue1970 Volume 17 Issue 3 Pages 108-115
Published: September 25, 1970
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSEffects of particle size of AlN (1.4-6.8 μ) and Al content (15-50 wt %) on the sintering characteristics of the system AlN-Al by nitriding reaction were studied. As the nitriding reaction of Al is highly exothermic, the temperature of the'samples rises rapidly on sintering. The exothermic effect and the texture of sintered specimens were affected distinctly by the particle size of the raw material powders and by the composition.
In samples containing coarse AlN powder (4.3 and 6.8 μ), temperature rises extremely rapidly resulting in macroscopically heterogeneous texture. This is especially remarkable in the specimens containing 20-25 wt % Al. The degree of nitriding is 80-100 % with Al less than 35 wt %, while decreases distinctly with increase in Al over 35 wt %.
In samples containing A1N powder of 1.4 μ, both the reaction rates and the temperature rise are less resulting in the comparatively homogeneous texture and high degrees of nitriding.
These results were explained by the distribution of raw material powders in the samples.View full abstractDownload PDF (1759K) -
Osamu Yamaguchi1970 Volume 17 Issue 3 Pages 116-121
Published: September 25, 1970
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSSintering and the electrical properties of lead zirconate titanate (PZT) containing excess amount of PbO over the Stoichiometric composition have been presented.
(1) The formation and sintering of PZT were nearly complete at about 900°C, as examined by X-ray diffraction analysis, dilatometry and electron microscopy.
(2) Abnormal expansion was observed between 400°C and 700°C. Well-defined ceramics have been obtained by heating slowly at this temperature range.
(3) An electro-mechanical coupling coefficient comparable to that of BaTiO3 has been obtained by firing at temperatures as low as 900°C.View full abstractDownload PDF (1704K)
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