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Volume 32, Issue 1
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[in Japanese]1985 Volume 32 Issue 1 Pages 1-7
Published: January 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (468K) -
In Case of Plunger PenetrationKazutaka Makino, Masaharu Yamada, Takayuki Juda, Kohtaro Kuramitsu, Ju ...1985 Volume 32 Issue 1 Pages 8-13
Published: January 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIn general, the heterogeneity of powder bulk density distribution formed in the powder compacts of powder plastic processes determines the mechanical strength and the dimensional accuracy of the final product and therefore is taken to be one of the most important problems to be elucidated. In order to elucidate this problem, the methods to measure the heterogeneity of the powder bulk density of powder compact, especially including loose one, can be considered to play a very important role. However, they have not yet sufficiently been developed up to now. Then, in this paper, as a first step to overcome this difficulty, the plunger penetration into powder was noticed. And the possibility to estimate the above heterogeneity using the acoustic emission generated at the above penetration experiments was experimentally discussed. As a result, it was pointed out that the distance between neighbouring loose powder bulk density zones can be predicted from acoustic emission data.View full abstractDownload PDF (400K) -
Hiroshi Nagai, Fusaki Koshiishi, Ikuo Okada, Keiichiro Shoji1985 Volume 32 Issue 1 Pages 14-21
Published: January 25, 1985
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe isothermal oxidation behavior of Ni-15Cr sintered alloys with 1.0 mass% of dispersion of various rare earth oxides was studied in air at 1473 and 1523 K. The oxidation rate was very dependent on the type of the dispersoid. The dispersion of rare earth oxides except for Eu2O3 reduced the oxidation rate at 1473 K; whereas, the dispersion of Eu2O3, Dy2O3, Ho2O3, Yb2O3 and Lu2O3 increased the oxidation rate at 1523 K. The spalling of the scale was also dependent on the type of the dispersoid. All the rare earth oxides suppressed the spalling of the scale at 1473 K, while the rare earth oxides other than La2O3, Gd2O3, Tb2O3 and Er2O3 lost their effect on the suppression in the spalling of the scale at 1523 K. The dispersion of La2O3 showed an excellent effect both on the reduction in the oxidation rate and spalling of the scale.
NiO content increased in the scale formed on the alloys which showed large mass gain; whereas a single layered Cr2O3 scale without NiO was maintained on the alloys which showed better oxidation resistance. These results suggested that the rare earth oxides which induced into the scale might change the diffusivity and/or solubility of Ni ions in the Cr2O3 scale.View full abstractDownload PDF (3735K) -
Effect of Heat Treatment on the StructureMasao Morishita, Fusaki Koshiishi, Hiroshi Nagai, Keiichiro Shoji1985 Volume 32 Issue 1 Pages 22-26
Published: January 25, 1985
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSEffect of heat treatment on the structure of Nickel-base superalloy IN-100 prepared by liquid phase sintering and swaging was investigated.
The results obtained were as follows:
(1) It was ascertained that the exothermic reaction (1483-1408 K) found during equilibrium solidification is due to the precipitation of γ', and this γ' phase can be dissolved in the same temperature range during heating (the sintered and swaged specimen).
(2) Recrystallized grains in the specimen annealed at 1423 K were very fine, because coarse γ' particles remained. While growth of recrystallized grains was observed in the specimen annealed at 1473 K, because most of γ' particles dissolved.
(3) The structure formed at grain boundary by incipient melting (1498-1523 K) during sintering process was absorbed into matrix by holding below 1498 K. While the structure changed its composition with holding time at 1513 K, and approached to the equilibrium structure which contained a Zr enriched phase.View full abstractDownload PDF (4473K) -
Ei-ichi Sentoku, Yoshio Fujimura, Hiroshi Kawabata1985 Volume 32 Issue 1 Pages 27-34
Published: January 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSAt high cutting speed, the mutual diffusion of material element between the chip and the tool has a great influence on the crater wear on the tool face.
The purpose of this paper is to study the mechanism of crater wear under high speed cutting by the static diffusion test. So as to find out the relationship between diffusion amount and crater depth, the machining tests and diffusion experiments were carried out by the combination of cermet tool and plaincarbon steel. In the diffusion test, the test pieces were kept for six hours in vacuum at various temperatures from 1188 K to 1380 K.
The diffusion elements were measured by EPMA, and their amounts are represented by X-ray integral intensity factor. The mean free path of the compound carbide in the tool was measured by using SEM image. Machining tests were conducted on a lathe, and cutting speed was varied from 1.3 m/s to 6.7 m/s but depth of cut (2.5 mm) and feed rate (0.25 mm/rev) were maintained constant throughout the tests.
The main results obtained are as follows:
(1) The cutting temperature at high speed cutting has a great influence on the crater wearing rate. A correlative region between crater wearing rate and cutting temperature is under the control of diffusion wear.
(2) Ni in the tool and Fe in the workpiece diffuse the most in amount. The crater wear on the tool face progresses by the mutual diffusion of the material element.
(3) The decrease of mean free path between carbide grains restrains mutual diffusion, and the wearing rate is diminished.View full abstractDownload PDF (4794K) -
Takayuki Nishio, Yoshiro Iwama1985 Volume 32 Issue 1 Pages 35-40
Published: January 25, 1985
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSPhase analysis and magnetic measurements are made on SmCos liquid phase sintering magnet materials, to elucidate deterioration behaviour of coercivity during annealing at about 973 K. Results obtained are summarized as follows:
(1) Eutectoid decomposition of SmCo5 does not exist in Sm-Co binary system.
(2) Sm2Co7 and Co-rich SmCo5 phases coexist in non-equilibrium state in the liquid phase sintering magnet materials, and the Sm2Co17 phase is precipitated at about 973 K, leading in a decrease in coercivity.
(3) The deterioration behaviour of coercivity during annealing at various temperatures can be described as a kind of relaxation process, of which an activation energy is estimated about 230 kJ/mol.View full abstractDownload PDF (1704K)
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