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Volume 33, Issue 1
Displaying 1-9 of 9 articles from this issue
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[in Japanese]1986 Volume 33 Issue 1 Pages 1-10
Published: January 25, 1986
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (3499K) -
Hiroaki Imai, Hiroshi Kuno1986 Volume 33 Issue 1 Pages 11-14
Published: January 25, 1986
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSCompaction processes of α-Fe2O3 granules have been studied through changes of intra-and intergranular pore volume measured by mercury porosimetry.
Densification of compacts mainly occurred by the elimination of inter-granular pores due to the plastic deformation of granules. Intra-granular pores remained unchanged during the compaction process under the stresses below 1000 kg/cm2.
Amount of inter-granular pore increased with the increase of the binder concentration but was not dependent on the yield strength of granules.View full abstractDownload PDF (255K) -
Hideshi Miura1986 Volume 33 Issue 1 Pages 15-21
Published: January 25, 1986
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe author reported previously that the Young's modulus of sintered iron compacts measured by the resonance method was affected by the pore shape, rather than by the pore size and number. The purpose of this study is attempts to express quantitatively the effect of pore shape on Young's modulus and evaluate the degree of spheroidizing of pores in sintered iron compacts added by alloying elements such as P and Si. The results are summarized as follows:
Using the proposed pore shape factor, η, which is mainly based upon the Hashin's elastic theory, the relation between Young's modulus of compacts, E, and the porosity, s, can be simply and successfully expressed as E/E0=(1-ε)/(1 +ηε), where E0 is Young's modulus of bulk material. In the case of sintered iron compacts, the value of η takes about 1 for the spherical shape of pores, and 2 to 3 for the pores with rounded edges. Thus, the value of η increases as the pore shape becomes irregular and angular.
For a given amount of porosity, Young's modulus of Fe-P compacts sintered above 1050°C (eutectic temperature of Fe-Fe3P) is higher than that of Fe compacts alone, which is due to the appearance of spheroidized pores by the liquid phase sintering. Addition of 3 wt%Si to atomized iron powders is somewhat effective on the spheroidization of pores as compared to that of 0.4 wt%P for the same sintering conditions, e.g. 1150°C×1hr.
Young's modulus of Fe-2.5%Si-0.3%P compact increases with increasing sintering temperature, and the elastic behavior of the specimen sintered at 1200°C for 1 hr is comparable with that of the carbonyl sintered iron, and the value of η of the former reaches nearly 1. Moreover, it was found that sintered iron compact treated by the gas sulfurizing shows a considerably spheroidized pore structure.View full abstractDownload PDF (5223K) -
Koji Hayashi, Hiroshi Asanuma, Masao Itabashi1986 Volume 33 Issue 1 Pages 22-27
Published: January 25, 1986
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe effect of the average particle size or specific surface area on the expansion phenomenon observed in vacuum-sintering high density Cu powder compact without lubricant was investigated and mechanisms proposed so far for the expansion phenomenon were reconsidered.
The results obtained are as follows; (1) The critical relative density of green compact, i.e., the density above which the compact expands due to sintering, largely depended on the average particle size or specific surface area; It decreased with decreasing particle size or increasing specific surface area. (2) Among so far proposed mechanisms, both residual stress(or strain) and entrapped air in the compact were made clearl to have minor effects on the expansion. (3) The expansion was considered to be generally caused by CO2 and H2O gases evolved from the powder. The source of these gases was discussed in some detail.View full abstractDownload PDF (1536K) -
Kazuhiko Majima, Takahiro Isono, Keiichiro Shoji1986 Volume 33 Issue 1 Pages 28-33
Published: January 25, 1986
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe mechanical properties of sintered titanium were examined in relation to the oxygen content, and the sintering process using calcium as the getter of oxygen was investigated.
The results obtained are summarized as follows:
(1) The elongation of titanium sintered in vacuum by the conventional method was much lower than that of vacuum-melted titanium containing about the same amount of oxygen.
(2) The ductility of sintered titanium was considerably improved by using calcium as the getter of oxygen.
(3) The mechanical properties of sintered titanium were affected not only by the total amount of oxygen content, but also by the oxygen gathering around the pores during sintering.View full abstractDownload PDF (2980K) -
Kazuo Sasazawa, Toshimitsu Honda, Nobutatsu Yamaoka1986 Volume 33 Issue 1 Pages 34-37
Published: January 25, 1986
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSZn-Cu electrodes were composed on both surfaces of ceramic capacitors and their characteristic properties were investigated. An oxidation ratio of the fired Zn electrodes was examined by a chemical analysis or an XPS. It was found that Zn metals are oxidized at the ratio of ca. 50%. The electrical properties of a BaTiO3-based ceramic capacitor (Y5V) with a Zn-Cu electrodes were equal to those with a silver electrode. As a result of migration tests examined in distilled water, the reaction started after holding for 1 min. in a fired silver electrode, and for 9 min. in Cu plating and Zn-Cu electrodes, but no reaction occurred even more than 15 min. in a fired Zn electrode.View full abstractDownload PDF (230K) -
Tadahiko Watanabe, Hideshi Miura, Youichi Tokunaga1986 Volume 33 Issue 1 Pages 38-42
Published: January 25, 1986
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSSintered TiB2-1%CoB and TiB2-5%TaB2-1%CoB materials have high density and high trasverse rupture strength. In the present study, the densification mechanism of the above materials has been investigated. It has been found that even a small amount (1 wt% or less) of CoB added to TiB2 or to TiB2-5%TaB2 has a remarkable effect on densification, and that the mixture of TiB2-1%CoB shows remarkable shrinkage during sintering under the die pressure of 200 kg/cm2 even at 1400°C which is lower than the melting point of CoB. These results suggest that the densification of these materials is caused mainly by an activated sintering process under die pressure. In this process, atoms on the surface of TiB2 (or TaB2) grains dissolve into the CoB phase so that a carrier phase may be formed in the contact area between the TiB2 (or TaB2) grain and the CoB phase. Then, the surface atoms on any TiB2 (or TaB2) grain can diffuse rapidly to other grains through the carrier phase.View full abstractDownload PDF (2818K) -
Hisashi Suzuki, Hideaki Matsubara, Hiroki Kondoh, Takeshi Saitoh1986 Volume 33 Issue 1 Pages 43-47
Published: January 25, 1986
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe TiC0.7N0.3-14.0 vol%Mo2C-(12.0, 16.4) vol%Ni and TiG0.5N0.5-10.0 vol%Mo2C-(12.0, 16.4) vol%Ni alloys were sintered, HIPed and then resintered. The mechanical properties at room temperature and high temperature of 1273K, and the resistance to chipping and wear during cutting steels were studied for three sorts of alloys, that is, as sintered, HIPed and resintered alloys.
The highest transverse-rupture strength and the highest hardness at room temperature were obtained in resintered and HIPed alloys, respectively, independently of the nitrogen and nickel contents. The deformation at 1273K was most suppressed in the HIPed alloys. The results of cutting tests showed that the chipping and wear resistances were excellent in such alloys having high strength and high hardness, respectively. These results were discussed in view of the difference in microstructures among three sorts of alloys.View full abstractDownload PDF (1937K) -
Naoichi Yamamoto1986 Volume 33 Issue 1 Pages 48-50
Published: January 25, 1986
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSHydrothermal treatment of an equimolar mixture of Ni(OH)2 and γ-MnOOH in a 1 N-NH4OH solution gave a new compound NiMnO2(OH). The reaction temperature and pressure were 200°C-320°C and 100 MPa, respectively. SEM photographs showed that the compound had a characteristic rectangular shape and the size of particles was around 5μ×0.1μ×0.1μ. I.R. spectrum and powder X-ray diffraction pattern of the compound were also shown. By calcinating the compound in air atmosphere, it decomposed to a ferromagnetic NiMnO3 of illmenite structure near 350°C and further to Ni1.5Mn1.5O4 of spinel structure above 800°C. TG and DTA data were also given. This is the first case when a ferromagnetic NiMnO3 was obtained under the normal atmospheric pressure.View full abstractDownload PDF (1544K)
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