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Volume 40, Issue 4
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[in Japanese]1993 Volume 40 Issue 4 Pages 372
Published: April 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (65K) -
Tai-Whan Lim, Koji Hayashi1993 Volume 40 Issue 4 Pages 373-378
Published: April 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe authors had been interested in the sintered densities of MIM(metal injection molding) products : The sintering densification of the products were incomplete. The sintering densification of Cu, Cu-Sn, Cu-Ni and carbonyl iron fine powders for MIM were investigated under various conditions. It was found that the densification of Cu, Cu-Sn and Cu-Ni powders levelled off at about 95% of the theoretical density when sintered in H2 gas, but became complete when sintered in vacuum or by thee addition of foreign element which forms stable oxide or has low standard free energy(ΔGf°) of oxide formation. The carbonyl iron powder also showed incomplete densification when sintered in vacuum as well as H2 gas, but showed complete densification when the elements of low ΔGf° were added. These phenomena could be explained in general from the present authors' theory of "equilibrium gas pressure", i.e., whether the equilibrium pressure of gas generated in the reduction reaction of the oxide is larger or smaller than the surface stress(the driving force of shrinkage) of closed pores is one of the determining factors for the incomplete or complete densification.View full abstractDownload PDF (1965K) -
Yoshimitsu Kankawa, Katsuyoshi Saitou, Toshiyuki Kida, Katsushi Ono, Y ...1993 Volume 40 Issue 4 Pages 379-383
Published: April 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSInjection molding of metal powder with use of POM(polyacetal) was discussed.
The compound on this process consisted essentially of POM and depolymerization polymers. It was clearly that the rate of degradation of the compound which contains a good deal of polyacetal was faster than that of which contains a good deal of other depolymerization polymers (PBMA and PS) or random degradation polymers (PP(polypropylene) and EVA (Ethylene-vinyl-acetate)). On thermal debinding process, the degree of distortion of the test piece which contains a good deal of POM was smaller than that of the test piece of which contains a good deal of PP, and the sintered bodys contained the only 30 ppm carbon. The relative density of sintered body was 96%.View full abstractDownload PDF (1192K) -
Noboru Wade, Masaki Ohara, Okiyo Suda1993 Volume 40 Issue 4 Pages 384-387
Published: April 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThis study aims to make clear the mechanism of heterogeneous sintering, where the sintering is more delayed in the near surface of the material compared to that of the interior. This phenomenon is unique in metal injection molding. The mixed slurry with 93wt% SUS304 steel powders with mean dia. of 11.2μm and 7 wt% binder were subjected to the injection at 150°C, followed by isothermal debinding in air at temperatures of 250-300°C, then vacuum sintering isothermally at 1000-1300°C. During sintering. more amount of retained binder contained carbon in the near surface causes to generate higher vapor pressure of CO gas, implying that this results in delayed sintering because of the higher pressure which prevails against the reduction forces of necks, voids, or pores, whereas in the material interior, the vapor pressure is lower than the reduction forces.View full abstractDownload PDF (2028K) -
Hideshi Miura, Kohsuke Urakami, Shinji Ando, Tadatoshi Honda1993 Volume 40 Issue 4 Pages 388-392
Published: April 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSA wide variety of mechanical properies is possible in the metal injection molding (MIM) process. However, there still remains the issue of controlling the carbon content and structure in the final product by the difference of powder type. In this paper, MIM process for the 4600 steels has been studied by using prealloyed fine powder (average particle size: 12μm) contained 0.71wt.% carbon.
For the debinding approach, solvent debinding followed by final thermal debinding consisted of heating at 0.066K/s to 1173K produced the homogeneous structure and stiff compact enough for handling. The residual carbon content was mainly controlled by changing the fraction of H2in gas mixture of H2 and N2 during the final thermal debinding. Mechanical properties of the sintered and the heat treated MIM compacts with prealloyed fine powders were inferior to those of the same treated MIM compacts with elemental mixed powders, especially in the ductility. This is due to the insufficient desification of prealloyed fine powder (relative sintered density : 93-94%) and the difference of microstructures.View full abstractDownload PDF (3185K) -
Hideshi Miura, Hiroshi Gondou, Tomio Kouno, Tadatoshi Honda1993 Volume 40 Issue 4 Pages 393-396
Published: April 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSStructure and mechanical properties of injection molded high speed steels have been investigated by using water atomized powder. Debinding was performed by solvent extraction at 358K with n-heptane, followed by final thermal debinding at various temperature. The debound specimens were sintered at 1473K-1573K for 3.6ks in various gas mixtures of H2 and N2. The results obtained are summarized as follows:
(1)Solvent extraction was effective debinding process for a considerable shortening the binder removal time and preventing the distortion.
(2)Sintered density was increased with an increase of sintering temperature, at 1523K in N2 fully densified materials were obtained and were also seen finely and uniformly dispersed carbides precipitated on the matrix.
(3)Although the size of carbides precipitated was decreased with increasing the fraction of H2 in the sintering atmosphere, the density and hardness declined. This is due to a shortage of liquid phase content because of the decarburization.View full abstractDownload PDF (2328K) -
Mamoru Mabuchi, Kohei Kubota, Kenji Higashi1993 Volume 40 Issue 4 Pages 397-400
Published: April 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSMechanical properties of both materials processed by sintering or extrusion from machined chips were investigated, compared to an as-cast or an extruded one, for an AZ91 magnesium alloy. The sintering conditions were a temperature of 643K and a pressure of 100 MPa in air, and the extrusion conditions were a temperature of 643K and a ratio of 100:1 in air. As a result of tension tests at room temperature, the material processed by sintering showed a low ultimate tensile strength of about 80MPa and a low elongation to failure of less than 1%. On the other hand, the material processed by extrusion showed a high ultimate tensile strength of about 340 MPa and a high elongation to failure of 10%, which were almost the same as those of the extruded one. Also, superplastic-like behavior was found at 573K with 2 x 10-4 s-1 for the material processed by extrusion. These results suggest that magnesium alloys which show excellent mechanical properties at room temperature and high ductility at elevated temperatures can be processed by extruding machined chips.View full abstractDownload PDF (5138K) -
Effects of Feeding Speed in Linear PathHideaki Tsuru, Hideyuki Hiraiwa, Motonari Kawasaki, Takeo Nakagawa1993 Volume 40 Issue 4 Pages 401-404
Published: April 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIn powder filling into a die cavity, higher and uniform density with little weight variation is generally required. In contrast to the conventional feeding system with guiding rail, the 2-axis electric drive CNC feeder developed can move the feedshoe flexibly on die plate, and according to cavity shape the feeding conditions such as feeding path, position and speed can be easily changed on NC program. In this study, the effects of average and forward/backward feeding speed on filling density and horizontal distribution have been investigated.
Among 4 different types, the filling density into die cavities of deep ring (??70×??60×t30) and thin plate (??70×t2) exhibited greater decrease with an increase in feeding speed. Investigations of local density distribution revealed that the decrease with higher feeding speed for the deep ring was mainly caused by insufficient fill in whole area, and for the thin plate by the loss of powder at the end of cavity in feeding direction which was raked off with retracting motion of feedshoe.View full abstractDownload PDF (1481K) -
Masatomo Kamada, Setsuo Takaki, Youichi Tokunaga, Yasuyuki Ikeda, Hiro ...1993 Volume 40 Issue 4 Pages 405-409
Published: April 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDie Compactibility and strength of green compact were investigated for low oxygen titanium powder produced by means of induction drip gas atomization, and a technic to improve the green strength and repressing compactibility of the pre-sintered compacts were also examined.
Although the atomized titanium powder has good die compactibility owing to its high apparent density (55% in relative density), the green strength is not so high because the powder is spherical in shape. Therefore, the compacts pressed at low pressure have to be handled carefully. Addition of hydrided-dehydrided titanium powder (HDH powder) is quite effective in strengthening the green compacts, because of increase in contact area at powder/powder interface and an anchor effect by attachment of the HDH powder among large atomized powders.
Repressing compactibility of pre-sintered compacts produced from the mixture of the atomized titanium and HDH powders is also excellent. For example, the porosity decreases to less than 6.5% through 785MPa repressing process. High density titanium parts with correctly controlled dimension, therefore, can be producted by repress-resinter P/M process.View full abstractDownload PDF (3595K) -
Yasuhiko Mano, Takeshi Mochizuki, Isamu Sasaki1993 Volume 40 Issue 4 Pages 410-412
Published: April 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe quality of green bodies produced by die pressing method is mainly determined by pressure conductivity inside the die. The relationship between pressure conductivity and granulating condition of pellets was studied. Pressure conductivity is more affected by distribution of organic binder inside pellets than primary particle size.View full abstractDownload PDF (162K) -
Ichitaro Takaki, Keijiro Terashita, Kei Miyanami1993 Volume 40 Issue 4 Pages 413-416
Published: April 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIn general manufacturing process of ceramics with dry compaction, quantitative analysis of each element of the process and of whole process is necessary. In this study, it is clearified that the diameter of spray-dried granulated Al2O3 particle can be controled effectively by choosing rotation rate of atomizer. We showed that apparentdensity of green-compact is greatly influenced by apparent density of granulated Al2O3 particle, especially at low compaction pressure. Both granulated Al2O3 particle and the green-compact have higher density, if concentration of slurry is relative high. And then, only density of sintered Al2O3 jumps up at about 57 wt%. So. we decide that the optimum concentration is 57.0 wt%, where there is no problem on this condition.View full abstractDownload PDF (234K) -
Study of Fabrication ProcessKoji Hoshino, Tohru Kohno1993 Volume 40 Issue 4 Pages 417-420
Published: April 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSAl oxide dispersed Ni-Cu porous sintered alloy was fabricated by a tape casting process followed by a sintering process consisting of oxidation and reduction from Ni-45%Cu-5%Al atmized alloy powder. Conditions of the tape casting process and the relationship between sintering temperature and porosity of the sintered alloys were investigated.
Metal powder could be tape-casted in the viscosity range of the slurry during 10, 000-20, 000 cps. Thickness of the green compacts was proportional to blade height. Densities of the green compacts were similar to the tap densities of raw powders. After sintering, porosity of the sintered alloy changed little from the green compacts. These results indicated that the porosity (or density) of the sintered alloy made by this fabrication process could be predicted from the tap density data of raw powder materials.View full abstractDownload PDF (1334K) -
Study of Internal Oxidation of Al and Stability at High TemperaturesKoji Hoshino, Tohru Kohno1993 Volume 40 Issue 4 Pages 421-425
Published: April 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSNi-45%Cu-5%Al alloy powder was sintered into a porous sintered alloy and internally oxidized by a novel sintering process consisting of oxidation and reduction. It was oxidized and sintered in air in the temperature range of 450-1, 050°C and reduced by Hz at 700°C in order to investigate the oxidation behavior of Al. Compressive creep tests of the alloy were carried out in an anode environment of molten carbonate fuel cells at 650°C.
Upon oxidation, CuAl2O4 coating was formed over the surface of the original powder and Cu diffused out through the CuAl2O4 phase while Ni remained. Upon reduction of the alloy after oxidizing at 1, 050°C, network structure of CuAl2O4 appeared. The alloy had an excellent dimensional stability in the anode environtment of molten carbonate fuel cell.View full abstractDownload PDF (5997K) -
Seizo Takahashi, Hiroshi Kanai, Takeo Nakagawa1993 Volume 40 Issue 4 Pages 426-431
Published: April 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDeep cup shaped compact were formed by a uniaxial hydraulic press from alumina granule guranulated with small amount of resin binder PVA (Polyvinyl Alchohol) after admixing liquid paraffin. This granule could be automatically filled into a die cavity. In the case of green compact formed from granule with the sufficient flowability, the densified powder flowed from the bottom to the cup wall during compaction, and the difference in partial density of green compact could be reduced. This is caused by reason that liquid paraffin affects the lubrication between powders during compaction. When the difference in partial density of green compact was small, the diameter of sintered compact along the bottom to cup wall was shrinked uniformly from green compact.View full abstractDownload PDF (2080K) -
Masato Imamura, Kiichi Nakajima, Akira Yanagisawa, Hiroyuki Noguchi, T ...1993 Volume 40 Issue 4 Pages 432-435
Published: April 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSPorous ceramics were made by means of sintering the compacts manufactured by slurry casted mixtures of the powders of metal and ceramics in the atmospheres of various gases. According to this method, some near-net shaped porous ceramics were acquried owing to the balance of the size change between the expansion in the reaction process of the metal powders and the atomosphere gas and the shirinkage in the sintering process. Some conceptional descriptions about this methode are made in this paper.View full abstractDownload PDF (237K) -
Hideki Kyogoku, Takuo Toda, Kazumitsu Shinohara1993 Volume 40 Issue 4 Pages 439-443
Published: April 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe debinding and sintering conditions of titanium compacts made by injection moldings and the effect of the addition of Till powder on the sintering characteristics of Ti powder have been studied. Specimens were made of Ti and Till powder with 30, u m in average diameter which were blended with binders and injected into a metal mold of flexure test piece. These were sintered in vacua of 1Pa after debinding. In the case of debinding at 423K, specimens had microstructures of titanium grains with pores, but bulged on the surface. In the case of debinding at 523K and 593K, TiC particles precipitated in grain boundaries. The higher the sintering temperature was, the greater the density of sintered Ti compacts became regardless of the debinding temperature. The densification of Ti powder compacts could be remarkably improved by the addition of TiH powder.View full abstractDownload PDF (3133K) -
Mitsuru Nakamura, Ko-ichi Kamada, Hiroshi Horie, Sadato Hiratsuka1993 Volume 40 Issue 4 Pages 444-448
Published: April 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSCorrosion resistance of high strength P/M Austenite type stainlees steels obtained by the addition of boron or phosphorus was investigated. In this experiment, corrosion tests by JIS method were carried out by intergranular and general corrosion tests, and the corrosion resistance was compared with P/M stainless steels (3 types) and wrought stainless steel. As a result, on intergranular corrosion test using 65% boiling HN03 solution, a boron 0.2wt% added P/M stainless steel shows good corrosion resistance and the corrosion loss values are equivalent as compared to wrought stainless steel. Phosphorus 0.2wt% added P/M stainless steel shows poor corrosion resistance because of localized corrosion of phosphide that precipitated along grain boundaries. On the other hand, on general corrosion test using 5% boiling H2SO4 solution, the behavior of corrosion is closely related to the density of specimens.View full abstractDownload PDF (5442K) -
Hidenori Kohzuki, Muneyuki Motoyama, Yasuo Okuno, Kazutoshi Yamada1993 Volume 40 Issue 4 Pages 449-454
Published: April 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSHard BN films with cubic BN (c-BN) phase and soft BN films without c-BN phase were deposited on Si wafer by a reactive ion plating process with a hot cathode plasma discharged within parallel magnetic field. These BN films were left in air with relative humidity of about 30%, 65-85% and 100% for about 3000 hours. The atmospheric degeneration of these BN films was investigated by SEM observation and EPMA measurements. Small particles such as boron oxide, boric acid or ammonium borate were formed at the surface of soft BN films left in air. All BN films were cracked after leaving in air. The cracking became faster with an increase in the relative humidity of air. The cracking of soft BN films occurred more rapidly than that of hard BN films. The cracking of hard BN films was retarded by post annealing.View full abstractDownload PDF (3863K) -
Atsushi Hitomi, Akira Sato, Yukie Nakano, Takeshi Nomura1993 Volume 40 Issue 4 Pages 455-460
Published: April 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSEffects of the dopants on the electrical properties of the Ni-electrode multilayer ceramic capacitors have been studied. It is shown that the life time of insulation resistance under Highly Accelerated Life Testing (HALT) become much longer by doping with Y2O3 or V2O5 into dielectrics. There are many dislocation loops in the additive-free dielectric and they disappear by doping with Y2O3. It is supposed that Y plays the role of donar dopant compensating the oxygen vacancies which have a deleterious effect on the life time under HALT.View full abstractDownload PDF (4433K) -
Sachio Toyota, Mitsuhiro Takata1993 Volume 40 Issue 4 Pages 461-464
Published: April 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSPiezoelectric and optical properties were measured for PLZT with composition of X/65/35. Rapid increase of piezoelectric constants in PLZT above 8mol% substitution of La led to a decrease of optical transmittance. The composition in which transmittance coexists with piezoelectricity was 8.1/65/35. A transparent loudspeaker using the PLZT(8.1/65/35) showed a sound pressure of 70dB and a transmittance of 65% .View full abstractDownload PDF (1093K) -
Hiroaki Makino, Katsunori Yamada, Nobuo Kamiya, Shigetaka Wada1993 Volume 40 Issue 4 Pages 465-469
Published: April 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSA joining method of ceramic / metal shaft with high heat resistance has been developed. The joined assembly consists of ceramic shaft, cylindrical metal shaft and two kinds of brazing metals. The brazing metal which has low melting point fills in the vicinity of the open end of the clearance between the ceramic and the metal shafts, and the other one which has high melting points fills the bottom portion of the clearance. The cantilever beam flexural strength of the joint was 280 MPa at room temperature and the shear strength was about 7 MPa at 750°C. These mechanical properties, especially at elevated temperature are superior to other ordinal joining methods such as shrink fitting or active brazing method. This joining method can be applied to the joining of the ceramic turbine wheel to the metal shaft of the gas turbine which requires heat resistance up to 700°C.View full abstractDownload PDF (337K)
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