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Volume 20, Issue 8
Displaying 1-5 of 5 articles from this issue
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Yoshikazu Suzuki1974 Volume 20 Issue 8 Pages 255-260
Published: March 25, 1974
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe formability of high-density iron sheets, sintered at 850°C for 4 hours in hydrogen, subsequently coldrolled, and annealed in a two-stage process, was examined by using the Erichsen cupping test, the deep drawing test, and r-value measurement. The annealing textures of the iron sheets were also investigated by means of an X-ray pole figure method and magnetic torque curve analysis. The results obtained are summarized as follows: (1) The formability of high-density sintered iron sheets in this study was similar to that of low carbon iron sheets. (2) The high-density sintered iron sheets which were reduced within the range of 85% to 90% by the secondary cold-rolling before annealing, were mechanically isotropic in the sheet plane. (3) The annealing textures of high-density sintered iron sheets which were mechanically isotropic in the sheet plane, showed that the intensity of (111) [112] and (211) [011] orientations was strong, whereas that of (110) [001] and (110) [110] orientations was weak, and the (100) [011], (100) [012] and (311) [136] orientations appeared slightly in the texture of the sheets.View full abstractDownload PDF (1799K) -
Tadashi Igarashi, Kenya Motoyoshi1974 Volume 20 Issue 8 Pages 261-267
Published: March 25, 1974
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe purpose of this paper is to discuss the metallurgical characteristics of Fe-Cr and Fe-Cr-Ni a phase powders, containing 42.5%Cr and 44.5%Cr-17.5% Ni respectively, as raw materials for powder metallurgy. Alloying phenomena of the a phase powder were observed in the process of formation of Fe-25%Cr-28%Ni austenitic alloy by means of saturation magnetization, X ray diffraction method, and optical microscopy.
The results are summarized as follows:
(1) Fe-Cr a phase powders were transformed into a phase within about 5 minutes at 1000°C, and these powders behaved as Fe-Cr a phase alloy powders above 1000°C.
(2) Fe-Cr-Ni p phase powders were decomposed into y phase in which small particles of the a phase were dispersed.
During heating over 1000°C, these a phase particles grew into larger particles and then dissolved into the γ phase.
(3) Cr had been diffused from the a phase into matrix powder before it was transformed into the a or (a+γ) phase.
(4) Larger shrinkage was obtained when the compact contained Fe-Cr a phase powders than those of Fe-Cr-Ni.View full abstractDownload PDF (4692K) -
Masao Takahashi, Sadayuki Takahashi, Tomeji Ohno, Norio Tsubouchi1974 Volume 20 Issue 8 Pages 268-273
Published: March 25, 1974
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSVery pure lead zirconate titanate ceramics were prepared for an accurate determination of the characteristic values of piezoelectric properties. The ceramics were sufficiently matured by using pulverized calcined powders and by sintering with a gradual rise in temperature. Electromechanical activity of the ceramics became maximum when the ceramics were subected to poling at 100°C with a field intensity of 40 kV/cm for 10 min. Deterioration gave rise to the breakdown of ceramics along grain boundaries when the field intensity and the time of poling increased. Breakdown predominated in the ceramics belonging to tetragonal symmetry.
Breakdown seems to be caused by a decrease of intergranular binding strength, and this assumption was confirmed by measurement of the bending strength and observation of the fracture.View full abstractDownload PDF (2769K) -
Masao Takahashi, Norio Tsubouchi, Masatomo Yonezawa, Tomeji Ohno, Tsun ...1974 Volume 20 Issue 8 Pages 274-284
Published: March 25, 1974
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSPerovskite solid solutions exist throughout the ternary system Pb(Mn 3+ 1/2Nb 1/2)O 3-PbTiO3 PbZrO3 and in up to 40mol% of the first component in Pb(Mn 2+ 1/3Nb 2/3)O 3-PbTiO3-PbZrO3; at higher concentrations, a mixture of perovskite and pyrochlore phases was obtained. With Pb(Mn 2+ 1/3Nb 2/3)O3, ceramics showed enhanced piezoelectric activity and increased mechanical quality factor, both in comparison to the PbTiO3-PbZrO3 binary and with Pb(Mn 3+ 1/2Nb 1/2)O 3. Much improved piezoelectric properties were obtained, when manganese ions were regarded as divalent ions, in comparison with the case of trivalent ions. The difference seems to be caused by different amount of space charge generated in the ceramics, resulting from the co-existence of manganese ion and niobium ion. The amount in the former ceramics is much larger than that of the latter. The Curie point and electrical resistivity of these ceramics remain sufficiently high for practical use.View full abstractDownload PDF (573K) -
Hisashi Suzuki, Shinziro Tsuchiya, Yasunori Fuke, Kozi Hayashi, Teruya ...1974 Volume 20 Issue 8 Pages 285-286
Published: March 25, 1974
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe WC, Co and Zn powders, having usual grain size, were used as starting materials, and this mixture was sintered in vacuum or in H2 at 1350-1410°C for 1 hr. As the result, WC-(6-30)%Co alloy specimens without any zinc content were obtained. Various properties of these alloys were studied and the following results were obtained. (1) It was confirmed that extremely high-strength cemented carbide could be obtained by this method, that is, by putting zinc powder in the (WC+Co) mixture. In this case, the other properties besides the strength seemed to be the same as usual alloys. (2) The increase in strength was sharp in WC-(10-15)%Co alloy, and the bending strength were, for example, 370 and 390 kg/mm2 in WC-10%Co and WC-15%Co high carbon two-phase alloys respectively (according to the test of ASTM standard).View full abstractDownload PDF (149K)
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