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Volume 40, Issue 5
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[in Japanese]1993 Volume 40 Issue 5 Pages 478
Published: May 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (93K) -
Ritsu Miura, Sejij Takamori1993 Volume 40 Issue 5 Pages 479-483
Published: May 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSIn MIM (Metal Injection Molding) technology, moldability of feedstock and resistivity of compact to debinding deformation are very important to mold highly complex shapes without defects and to maintain close tolerances of final products, respectively.
In this paper, the effects of powder characteristics on the flowability of feedstock and the deformation of compact during thermal debinding were studied using 6 kinds of powders. For specific powders, the effect of binder content was also investigated. The flowability of feedstock was estimated by MFR (Melt Flow Rate) at 170°C, while the debinding deformation was determined in bending mode using rectangular bar specimens supported both ends.
As expected, spherical powders exhibited much higher flowability of feedstock than irregular powders, showing flowability in proportion to the tap density. For irregular powders, however, there observed no correlation between the folwability of feedstock and the tap density of powder. The flowability of feedstock increased with increasing binder content for both spherical and irregular powders. On the other hand, spherical powders showed much lower resistance to debinding deformation than irregular powders. For both spherical and irregular powders, the resistance to debinding deformation increased with decreasing mean particle size and decreased with increasing binder content.
It was concluded the above results that there exists inverse relationship between the flowability of feedstock and the resistance of compact to debinding deformation because they are inversely affected by the same factors i.e. interparticle friction and/or interparticle separation.View full abstractDownload PDF (1624K) -
Junjiro Takekawa1993 Volume 40 Issue 5 Pages 484-487
Published: May 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe distortion of injection molded thin cylindrical compacts during sintering process was investigated. SUS316L powder having mean particle size of 10μm was used.
It was shown that the compacts were distorted remarkably during sintering when they were not sufficiently debound to the binder removal level of 95% or more.
In order to minimize the distortion during sintering the compacts should be sintered, setting on the well polished porous Al2O3 plate, in such a heating profile that the shrinkage proceeds linearly with increasing temperature.View full abstractDownload PDF (222K) -
Hiroshi Yoshimura, Toshiharu Nomoto1993 Volume 40 Issue 5 Pages 488-496
Published: May 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSHot isostatic pressing (HIP) is a manufacturing process which forms high quality products from ceramic or metal powders at high temperature and high pressure. The most important problem for the HIP process is to get densified near-net-shape products. Because the sintering behavior during HIP depends on many process parameters, analytical method is greatly required to select the optimum process variables without trial and error procedures.
In this paper, governing equations for heat conduction, densification rate and shape change are presented to predict the sintering deformation behavior during HIP. Computer analysis makes clear the relation between temperature, density distributions and sintering deformation behavior. Measured results of density and shape changes in practical HIP equipment show a good agreement with the calculated results.View full abstractDownload PDF (3599K) -
Hirishi Ochiai, Osamu Kimura1993 Volume 40 Issue 5 Pages 497-500
Published: May 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThis study aims to densify sintered polycrystalline Mn-Zn ferrites, using O2-HIP treatment in Ar atmosphere containing 0.1 % O2. It is expected that this treatment enables to economize use of packing ferrite powders or annealing process as in Ar-HIP treatment. After HIP treatment of 49 MPa at 1200°C for 1 hr, the HIPed ferrite reaches almost theoretical density. Its permeability at 100 kHz decreases from 3600 to 2500, while the loss factor, tan δ/μ, decreases to less than half.View full abstractDownload PDF (2415K) -
Kohei Taguchi, Michihiko Ayada, Hideo Shingu1993 Volume 40 Issue 5 Pages 501-505
Published: May 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSA pseudo-HIP (PHIP) process has been applied for the reactive synthesis of near-net shape Ti-Al intermetalic compound materials. Ti-Al compound specimens of full density with composition range Ti-46 to 52at%Al were obtained after PHIP treatment at 1373K to 1623K. The high temperature bending strength of the Ti-48at%Al increased by increasing PHIP temperature. After PHIP treatment at 1623K the volume percent of lamellar structure increased by increasing the Ti content and a full lamellar structure of The Ti-46at%Al gave the highest strength. A structure of matrix gamma and small lamellar grains that was obtained in the range of Al rich composition had high yield strength at high temperature.View full abstractDownload PDF (3105K) -
Masafumi Miyajima, Akira Kawasaki, Ryuzo Watanabe, Jing-Feng Li1993 Volume 40 Issue 5 Pages 506-510
Published: May 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe pseudo-HIP method was applied to the hot compaction of two kinds of stainless steel powders with average particle sizes of 53 and 0.06 microns, respectively. The preheated powder preform, encapsulated in a glass tube, was compacted in a steel die using preheated alumina granules as a pressure-transmitting medium. The densification behavoir and microstructural development were investigated by varying compacting pressure and temperature. It has been found that full dense compacts with fine-grained microstructure can be obtained at temperature 300-400K lower than with normal sintering.View full abstractDownload PDF (4668K) -
Hidehiko Kobayashi, Akihiro Ueda, Takashi Mitamura1993 Volume 40 Issue 5 Pages 511-515
Published: May 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSPorous alumina prefired bodies filled with 10- 40wt% of Al2O3 were fabricated via impregnation - dehydration - thermal decomposition (impregnation method) using a saturated Al(N03)3 solution. The possibility of utilizing the impregnation method as a means of near net shaping for ceramics was investigated by evaluating the sinterability of these ceramics. Al2O3 prefired bodies filled with 40wt% of Al2O3 were prepared by repeating the impregnation process at 400° to 800°C. The impregnated aluminum oxides were amorphous, η- and α -Al2O3 according as the thermal-decomposition temperature. Both the sinterability of an Al2O3 prefired body with high density and the dimensional stability of the fabricated Al2O3 sintered body were markedly improved with this process. It was observed that the fine structure of the Al2O3 sintered body derived from an Al2O3 prefired body with high density-filling of Al2O3 was made uniform by controlling the crystallization and transition to α-Al2O3 of thermally decomposed filled powders.View full abstractDownload PDF (1695K) -
Masato Imamura, Kiichi Nakajima, Akira Yanagisawa, Takeo Nakagawa1993 Volume 40 Issue 5 Pages 516-519
Published: May 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSPorous alumina-silicon composite with size stability and with sufficient mechanical strength was maufacutured by sintering the green compact of the slurry cast of the mixed powders of aluminum and mullite in air. The variation of the specimen size after sintering was found to be little due to the balance of the shirinkage during sintering and the expansion caused both by the oxidation of excess aluminum in air and by termit reaction of silica and aluminum.View full abstractDownload PDF (1439K) -
Masato Imamura, Kiichi Nakajima, Michiyoshi Motoyoshi, Akira Yanagisaw ...1993 Volume 40 Issue 5 Pages 520-523
Published: May 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSNear net-shaped porous alumina with considerable mechanical strength was fabricated in the following processes. The green compact of the mixed powders of aluminum and alumina formed by slurry casting was dried and sintered in air. The change of the specimen size was expectedly very small because the expansion due to the oxdation of metal and the sintering shirinkage were evenly balanced.View full abstractDownload PDF (1542K) -
Masato Imamura, Kiichi Nakajima, Yoshitaka Ichikawa, Akira Yanagisawa, ...1993 Volume 40 Issue 5 Pages 524-527
Published: May 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSNear net-shaped porous aluminum nitride composite with considerable mechanical strength was fabricated in the following processes. The green compact of the mixed powders of aluminum and alumina formed by slurry casting was dried and sintered in nitorgen atmosphere. Before and after sintering, the change of the size of the specimen was expectedly small because the expansion due to the nitridation of metal and the sintering shirinkage were evenly balanced.View full abstractDownload PDF (1565K) -
Yoshimitsu Kankawa, Katsuyoshi Saitou, Yasunari Kaneko, Yukio Sasatani1993 Volume 40 Issue 5 Pages 531-535
Published: May 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIt is necessary to reduce the debinding time in powder injection molding process. Therefore, recently, there are methods such as ANAX process of removing the binders and the solvent debinding which can solve the problems mentioned above becomes to get much attention. Here discussed solvent debinding of injection molded Fe-36%Ni with use of polyvinylbuthyral as organic binder. The all organic binders of the componud dissolved into the solvent in this process, although the all ones of the compound could not be always dissolved into the solvent on conventional solvent de-binding process. In this process, the sintered bodys scarely containing carbon were produced under these conditions ;(1) extraction binder volume was at least 30vol% after the solvent debinding process, and (2) after solvent debinding process, the optimum maximun temperature on thermal debinding process was 350°C in air.View full abstractDownload PDF (3955K) -
Yoshimitsu Kankawa, Katsuyoshi Saitou1993 Volume 40 Issue 5 Pages 536-540
Published: May 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSInjection molding of metal powder with use of depolymerization polymers were discussed.
The compound used by this process consisted essentially of PBMA(Polybutyl-methacrylate) and PS (Polystylene). It was clarified that the rate of degradation of this compound were faster than that of compound which contain a good deal of random degradation polymers (PP(Polypropylene) and EVA(Ethylene-vinyl-acetate)). On the compound which contain a good deal of depoiymerization polymers, the degree of distortion of the test piece on thermal debinding process increased with an increase of PBMA content of the compound, the sintered bodys include only 20ppm of carbon, and the relative density of sintered body was 96%.View full abstractDownload PDF (2214K) -
Sunao Sugihara1993 Volume 40 Issue 5 Pages 541-544
Published: May 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe report describes the solid reaction between TiO2 and BaCO3 under a CO2 laser irradiation. The powders of TiO2 and BaCO3 are mixed for a compaction and the green pellets (thickness; 0.95mm) were irradiated with the powers of 1.14, 1.40, 1.85 and 2.14 kW/cm2. The temperatures were 1053-1500 K depending on the laser powers. The laser power more than 1.85 kW/cm2 led to the sintered body from the green pellet. The formation of BaTiO3 was identified with X-ray diffraction analysis. The scanning electron microscopy revealed that the product was the porous ceramics with necking between grains. The sintered density was as low as 60-70% TD. The permittivity of BaTiO3 after irradiation at 2.14 kW/cm2 was 80 approximately.View full abstractDownload PDF (2430K) -
Akira Sato, Atushi Hitomi, Yukie Nakano, Takeshi Nomura1993 Volume 40 Issue 5 Pages 545-549
Published: May 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSInsulation resistance of dielectric for Ni-electrode multilayer ceramic capacitors has been studied with reference to the chemical composition of dielectric. It is shown that dielectrics have anti-reduction property when sintering in a reduced atmosphere in case of A/B>1 or MnCO3-addition. On the other hand, the insulation resistance drops by doping with CaCO3. The insulation resistance become higher by annealing in an oxidizing atmosphere after sintering, as the substitution amount of Ca for Ba becomes larger.View full abstractDownload PDF (4036K) -
Kenji Suzuki, Tadashi Kousaka, Koichiro Koyama1993 Volume 40 Issue 5 Pages 550-555
Published: May 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe effect of water vapor in a calcining atomosphere on Tc, off of YBa2Cu3O7-x was investigated using the electrical resistivity method, X-ray diffraction analysis and carbon analysis. The results are as follows:
(1) The critical temperature(To, off) elevated with increasing H2O partial pressure, reached a maximum(90.5K) at a H2O partial pressure of about 5kPa, and then lowered.
(2) The water vapor remarkably accelerated the decomposition of BaCO3. However, the excessive addition of water vapor was detrimental because of the formation of an unknown phase.View full abstractDownload PDF (286K) -
Makoto Tamura, Yoshikatsu Harada, Mitsuhiko Sato, Takemi Yamamura1993 Volume 40 Issue 5 Pages 556-560
Published: May 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSFour types of glass matrix composites (GMC) were fabricated to investigate the effect of the fibre/matrix interface on the mechanical property of GMC. Pyrex was used as the matrix and an Alumina fibre, a carbon fibre, and two different types of Si-Ti-C-O fibre (F and S grade) were used as the reinforcement. Alumina fibre/pyrex composite was the poorest GMC of all, which failed catastrophically with low strength. Other three GMCs performed well, in particular, F grade Si-Ti-C-O fibre/pyrex composite showed high strength with woody fracture manner. The fibre had a very thin carbon layer on its surface, and an interface carbon layer which had relatively weak interfacial bond between the fibre and the matrix seemed to be formed easily when fabricated. The high temperature flexural strength of F grade Si-Ti-C-O fibre/pyrex composite increased drastically at about 400°C and then decreased as the test temperature increased. The poor oxidation resistance of the carbon fibre/pyrex composite was due to that of the fibre itself, while the oxidation resistance of the Si-Ti-C-O fibre/pyrex composites seemed to depend upon that of the interface layer. The Si-Ti-C-O fibre/pyrex composites retained their strengths for more than 100 hours in air at 500°C.View full abstractDownload PDF (4237K)
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