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Volume 44, Issue 11
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[in Japanese]1997 Volume 44 Issue 11 Pages 984
Published: November 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (80K) -
Tomio Kono, Akira Horata, Tetsuya Kondo1997 Volume 44 Issue 11 Pages 985-992
Published: November 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe properties of typical pure Ti and Ti-6Al-4V alloys produced by Metal Injection Molding (MIM) process have been investigated in detail after optimization of the powder characteristic, debinding and sintering conditions for the process.
(1) Sintered pure Ti using the blended in equal amount of hydrided-dehydrided and gas-atomized powders has better tensile strength (640MPa) and elongation (21%), which properties are similar to the JIS 3 grade of wrought pure Ti.
(2) Sintered Ti-6Al-4V alloys produced by both mixed elemental and prealloyed powders have good tensile strength (970MPa) and elongation (12%), which are almost comparable to those of wrought Ti-6Al-4V alloys.
(3) Polishability of sintered pure Ti is generally poor. However, the specific heat treatment leads to fairly improved polishability because of the grain refining which is also favorable for the mechanical properties.View full abstractDownload PDF (5334K) -
Yoshiyuki Kato1997 Volume 44 Issue 11 Pages 993-998
Published: November 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDevelopment of MIM Industries in various Asian countries has been activated by their R&D, and also their MIM production activities are being established by the imported manufacturing Plants from Europe, America and Japan which have various advanced technology during economic development in these countries. The trend of industrial activities on MIM in each country are different according as the surroundings of market situation and technology. In this report, the writer report the recent situation in Korea, Taiwan, Singapore, China, Malaysia, and India under the informations which were collected by the writer at practical visit to those countries.View full abstractDownload PDF (333K) -
Hideshi Miura, Masumi Nakai, Takeharu Baba, Tadatoshi Honda1997 Volume 44 Issue 11 Pages 999-1003
Published: November 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSIt is well known that many high performance sintered alloys have been produced by Metal Injection Molding (MIM) process so far. A Fe-Ni system is one of the objected alloys, and they are used for machine structural parts. Although assessment of the dynamic fracture properties such as fatigue strength is important to design a reliable sintered structual parts, there are few reports for the dynamic properties of MIM alloys even at the present time.
In this study, the behaviore of dynamic properties (impact and fatigue strength) for Fe-Ni (Fe-2, 4 and 7mass%Ni) alloys produced by MIM process has been investigated. Approximately 96% of theoretical density was obtained in all Fe-Ni alloys. Impact strength of MIM alloys was superior to that of the conventional P/M alloys, because the pore structure of the former was fine and spheroidized as compared to that of the latter. Fatigue strength was increased with increasing Ni content because of the solution strengthening and grain refining effects. Endurance ratio of MIM alloys was similar to that of the wrought alloys.View full abstractDownload PDF (3363K) -
Junjiro Takekawa1997 Volume 44 Issue 11 Pages 1004-1008
Published: November 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMetal injection molding (MIM) process for the SCM415 steel powder (water atomized, 8.3μm) has been performed paying most attention to keep the desirable carbon level in the sintered compacts. 0.4mass% graphite was added to the powder to control the C content. After debinding in air at temperatures ranging from 513K to 553, the compacts were sintered at 1548K for l8ks in H2 and N2 gas mixtures.
The carbon contents of MIM sintered compacts decreased with the increase of debinding temperature, and the debound compact at 553K showed almost 0 mass%, regardless of the sintering atmosphere. The maximum carbon content was obtained by sintering in 10vol% H2/N2, and the carbon content decreased with increasing H2 concentration. By sintering in pure H2, the carbon contents were closed to 0 mass% in all the compacts, regardless of other conditions. The tensile strengths of the sintered compacts were increased with the increase of the carbon contents. The compacts sintered in lower H2 concentration had a tendency to show high strength, even at the same carbon level.View full abstractDownload PDF (2089K) -
Hideshi Miura, Shinichiro Nishi, Takeharu Baba, Hisatoshi Miyazaki, Ma ...1997 Volume 44 Issue 11 Pages 1009-1013
Published: November 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSHigh density and high performance properties have been required to the sintered machine structural materials such as alloy steels, together with the improvement of recent machine functions. As one of the solution, metal injection molding (MIM) technique is hoped to be a suitable process for meeting the above requirements.
In this study, the effect of debinding and sintering conditions on the heat treatment characteristics and mechanical properties of injection molded SCM415 alloy steels were investigated. Retained carbon content, density, microstructure, and mechanical properties of the MIM alloy steels were strongly dependent on the debinding, sintering, and heat treatment conditions. Especially, retained carbon content was precisely controlled by optimizing the debinding and sintering conditions. For the carburization, case hardening was possible and the case depth was similar to the case of wrought steels. Finally, the obtained tensile and fatigue strength of MIM alloy steels were superior to those of the conventional P/M alloy steels.View full abstractDownload PDF (1382K) -
Takeharu Baba, Hideshi Miura1997 Volume 44 Issue 11 Pages 1014-1018
Published: November 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSIn our previous studies on the 4600 steels produced by Metal Injection Molding (MIM) process using mixed elemental powder, the fine heterogeneous microstructure caused by the agglomeration of spiky Ni powders was reported to be significantly effective for the static and dynamic fracture properties. In this study, the effects of heat treatment condition and different type of Ni powder on the mechanical properties of injection molded 4600 steels using prealloyed and mixed elemental powders were investigated to secure the efficacy of the fine heterogeneous microstructure. The obtained results are as follows:
1) The heat treated steels using the prealloyed powder showed the homogeneous tempered martensitic microstructure, while the steels using mixed elemental powder showed the fine heterogeneous microstructure consisted of tempered martensitic matrix and martensite or retained austenite phases, which were caused by the segregation of Ni powders.
2) For the tempered steels at 473K, the fine heterogeneous microstructure contained Ni rich phases was effective for the tensile and fatigue strengths. On the other hand, there was not clearly seen the efficacy of the heterogeneous microstructure in the tempered steels at 823K because of the homogenization.
3) The agglomeration of Ni powders with spherical shape investigated with the debound steels was fewer than that of Ni powders with spiky shape, which lead the decrease of Ni rich phases even in the heat treated steels, resulted in poor tensile strength.View full abstractDownload PDF (5400K) -
Hideki Nakayama, Hideki Kyogoku, Shinichiro Komatsu1997 Volume 44 Issue 11 Pages 1019-1023
Published: November 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe effect of process conditions on the microstructure and mechanical properties of SUS630 compacts made by metal injection molding were investigated. The compacts were made by injecting the mixture of gas-atomized SUS630 powder and polyamide binder into a metallic mold. The compacts were debound in air at 513K, 553K and 593K for 7.2ks, and sintered in vacuum at 1523K, 1573K and 1623K for 7.2ks. The carbon content of the sintered compacts was found to be controlled accurately by the debinding temperature. The microstructures of the sintered compacts varied with carbon content: they consisted of martensite and δ-ferrite at lower carbon content, and of martensite and austenite at higher carbon content. The mechanical properties also changed significantly with the carbon content.View full abstractDownload PDF (1417K) -
Hideshi Miura, Mari Yonetu, Akira Okuyama1997 Volume 44 Issue 11 Pages 1024-1028
Published: November 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSFor miniaturization and complication of the shape of electronic devices in recent years, improvement of magnetic properties are also being required to the soft magnetic components. Fe-Si-Al alloy is well known to be a soft magnetic material suited for a magnetic head because of high permeability and magnetic flux density as well as high wear-resistance. However, this alloy is very brittle and difficultly workable. Therefore, metal injection molding (MIM) process is hoped to be a suitable production route for hard and brittle materials such as Fe-Si-Al alloy because of providing net shape components.
In this study, the effect of MIM process conditions on the magnetic properties of Fe-Si-Al alloys has been investigated using a gas-atomized powder. Since this alloy melted at high temperature over 1523K, the optimum sintering temperature was found to be 1523K at which the obtained relative density was more than 98%. However, the magnetic properties of the compacts sintered in both hydrogen and vacuum atmospheres were relatively inferior to that of the wrought materials. This was seemed that the domain wall migration was prevented by the fine grain size and the retained oxides. By the continuous process including the debinding and sintering steps together, the compacts showed good magnetic properties because of the small amomts of oxides and coarse grain size.View full abstractDownload PDF (5563K) -
Kiyotaka Kato, Akihiro Matsumoto, Tei Ieki1997 Volume 44 Issue 11 Pages 1029-1034
Published: November 15, 1997
Released on J-STAGE: July 12, 2010
JOURNAL FREE ACCESSIn this paper, tensile properties at high temperature were investigated on the sintered TiAI compacts produced by MIM process. The sintered Ti-45A1, Ti-48AI, Ti-50A1 and Ti-52A1(at.%) compacts showed the relative densities more than 95% by sintering at 13751 for.2hr in vacuum(10-2Pa order).
The results obtained were summarized as follows:
(1) The tensile strengths at 800°C for Ti-45A1, Ti-48AI and Ti-50Al compacts were almost equal to the strength at room temperature, which were in the range of 370 to 400MPa. The Ti-52Al compact showed smaller tensile strength at 800°C(330MPa) than the strength at room temperature(430MPa). The elongations at 800°C for TiAl compacts increased with increasing Al content. Especially, the Ti-52A1 compact showed the highest elongation of 13%.
(2) The tensile strengths at 1000°C for all TiAI compacts were smaller(-200MPa) than the strength at 800°C, which were sligthly increased with decreasing Al content. The elongations at 1000°C were still more than 10%.View full abstractDownload PDF (3720K) -
Akihiro Matsumoto, Kiyotaka Katoh, Kunisuke Andoh1997 Volume 44 Issue 11 Pages 1037-1042
Published: November 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe consolidation of injection molded compacts by Pulsed Discharge Sintering Process, that enables rapid sintering under the condition of high temperature combined with pressure application in various environments, is proposed as a novel process of near net forming. The proposed PHIP (Pseudo Hot Isostatic Pressing) technique using a pressure-transmitting medium of spherical graphite powder makes it possible to manufacture compacts with three dimensional shapes (PHIP-PDS). For the first time, temperature distribution along radial direction of graphite die was measured in the real time under PHIP-PDS. There existed temperature gradient in the die, that depended on holding temperature, inside diameter and thickness of die. Titanium powders, mixed with 36.2 vol% organic binder, were injection molded. After debound in 100 Torr Ar atmosphere at various temperature, they were consolidated by PHIP-PDS process. The temperature necessary to fully densify them under 50 MPa pressure was 1373K for PHIP-PDS, which was about 300K higher than that for PDS. Contraction percentage of the compacts was 25% for longitudinal (loading) direction, while 6% for transverse direction. Chemical analysis of titanium compacts showed 0.12-0.17wt% carbon and 0.22-0.28wt% oxygen.View full abstractDownload PDF (4574K) -
Yosuke Nakada, Miho Yamazaki, Toshio Kimura1997 Volume 44 Issue 11 Pages 1043-1048
Published: November 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSRigid inclusions retard the densification of matrices. This study deals with the effects of inclusion/matrix particle size ratio and surface modification of inclusions on the densification of Ag matrix. The surface of YSZ inclusions was modified by chemical roughening and/or electroless Ag-plating. The sintering behavior and microstructure development of Ag-matrix composites containing surface-modified YSZ with different inclusion/matrix particle size ratio were investigated. The densification of the matrix with higher inclusion content and/or smaller inclusion/matrix particle size ratio was suppressed more significantly, irrespective of the sinterability of matrix. The chemical surface roughening of inclusions resulted in an increase in the hindrance of densification of matrix. On the other hand, the electroless Ag-plating of inclusions relaxed the hindrance of the densification. The densification of matrix with high inclusion/matrix particle size ratio led to the formation of density variation in the matrix. Pores located around inclusion particles remained in the matrix with low inclusion/matrix particle size ratio. Channel structure of pores formed in the matrix, particularly when the particle sizes of matrix powder and inclusion powder were almost the same.View full abstractDownload PDF (5273K) -
Masakuni Ozawa, Osamu Kato, Ken-ichi Araki, Suguru Suzuki1997 Volume 44 Issue 11 Pages 1049-1054
Published: November 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe Solid-state reaction, sintering and hydrocarbon-removal activities of composite powders in La-Ni-Al2O3 system were studied toward their application to heat-stable exhaust catalyst. The different routes with the impregnation technique were applied to prepare the composite powders. X-ray diffraction revealed the following solid-state reactions; γ-Al2O3 (+NiO) + La2O3 (500°C)→γ-Al2O3 (+NiO) + LaAlO3 (800-1000°C)→γ-Al2O3 (+NiO) + LaAlO3 + NiLaAl11O19 (1000-1100°C). The La-stabilization was effective to retain large surface areas of these composite powders. The C6H6 removal activities were compared for the Ni-La-Al2O3, heated at 800°C and 1000°C. The catalytic performance depended on microstructures in the La-Ni-A12O3 composite powders from different routes.View full abstractDownload PDF (358K) -
Ryohei Kumagae, Masami Yoshitake, Osamu Iwatsu, Kensuke Hidaka1997 Volume 44 Issue 11 Pages 1055-1060
Published: November 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSTiAI electrode was made by sintering of CIPed compact with Ti and Al mixed powder at the temperature of 1673K. The electrode made by this method was composed of fully lameller structure of Ti3Al and TiAl intermetallic compounds without a trace of Ti or Al metallic residue.
As the results of testing this electrode for plasma rotating electrode process (PREP) in helium gas atmosphere, it was seen that powders obtained have the same properties, such as particle sphericity, particle size distribution and chemical compositions, as powders produced by using the electrode prepared from the melting ingot. PREPed Ti-Al powders consist of two kinds of particles being different in micro-structure, but thesame compositional ratio of Ti to Al, the one has a dendritic surface (D Powder) and the other has a surface relief (M Powder), of which the micro-structure shows α2 single phase and is suitable for the compact forming by hot pressing compared to that of D powders.
In this work, M particles being distinguished by SEM surface micro-structure were observed in the finer side of the particle size distribution and presumed that one ofthe facter to produce the M powder is a cooling rate on PREP.View full abstractDownload PDF (3854K) -
Vacuum Pressure Assisted Slip Casting and Mechanical Properties of Sintered BodyMasaki Maeda, Yasuo Shibasaki1997 Volume 44 Issue 11 Pages 1061-1064
Published: November 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSSlip casting of high purity mullite powder produced by coprecipitation method was studied to fabricate mullite ceramic parts with complicated shapes. The preparation conditions of well dispersed slurry (71mass% solids) was prepared by addition of deflocculant (0.2mass%), binder (0.3mass%) and defoamer (0.15mass%). Shaping of test pieces were used by the vaccum pressure assisted slip casting system with a porous polymer resin mold. The mechanical properties of the sintered body were investigated. High density mullite ceramics was obtained at 1650°C for 5hr. The sintered body of high purity mullite showed a flexural strength of about 290MPa and a Weibull modulus of 20.0 at room temperature.View full abstractDownload PDF (227K)
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