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Volume 40, Issue 9
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[in Japanese]1993 Volume 40 Issue 9 Pages 844
Published: September 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (62K) -
Tatsuya Shimoda1993 Volume 40 Issue 9 Pages 845-850
Published: September 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSBonded rare-earth magnets, which are produced by binding rare-earth magnetic powder with resin, are now widely used in various kinds of small sized electric equipment such as watches, cameras, computer periferals, headphone stereos, and video tape recorders. These magnets not only have advantages related to their magnetic properties, shape flexibility and reliability, but also can be manufactured with relative low cost. Because of these reasons, production amount of the rare-earth bonded magnets has grown rapidly in the last decade. In 1991, thier recorded production was 32 times as high as in 1981. Now much research concerning these materials are actively being conducted. Several kinds of new materials have been found and new process technologies developed. In the future, further improvement in magnetic properties and cost reduction would lead to the large application of these magnets.View full abstractDownload PDF (405K) -
Tetsuji Harada, Toshiro Kuji1993 Volume 40 Issue 9 Pages 851-854
Published: September 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMechanical grinding of Nd15Fe77B8 powders was carried out under argon, hydrogen, and nitrogen atmosphere. It was found that Nd15Fe77B8powders absorbed large amounts of hydrogen and nitrogen when mechanical grinding was performed in either hydrogen or nitrogen atmosphere. The absorption of hydrogen and nitrogen during mechanical grinding caused significant grain refinement but reduced the coercivity values. Heat treatment of the hydrides resulted in desorption of hydrogen gas. When the hydrides were annealed at relatively lower annealing temperatures, the resultant powders consisted of α-iron and neodymium phases and showed low coercvity values. On the other hand when the hydrides were annealed at relatively higher annealing temperature, the resultant powders consisted of Nd2Fe14B crystallites and showed high coercivity values. Heat treatment of the nitrides did not result in desorption of nitrogen gas but they decomposed into α-iron and neodymium nitrides.View full abstractDownload PDF (2654K) -
Keijiro Terashita, Kei Miyanami, Kazunori Sakamoto1993 Volume 40 Issue 9 Pages 855-858
Published: September 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSAs a fundamental study of production of magnetic paint film for high density recording, dispersion of magnetic powder was performed by Bead Mill under various operating conditions, and magnetic paint films were coated with the paint. The dispersibility was evaluated as a coated videotape by glossiness and surface condition. Besides, the electric-power comsumption of agitator was continuously measured during the dispersion operation, and viscosity of the paint was measured.
It was found that high-grade vigeotape is produced by using magnetic paint made around steady power comsumption in dispersion operation. From the results, it was indicated that granulation end-point is around steady power comsumption. And it clarified that in order to obtain well-dispersed metal paint for high-grade videotape at high recording density, dispersion operation should be performed around filling rate of media = 46.3%, peripheral speed of agitator U = 12m/sec.View full abstractDownload PDF (266K) -
Keijiro Terashita, Kei Miyanami, Kazunori Sakamoto1993 Volume 40 Issue 9 Pages 859-862
Published: September 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSIn this work, surface treatment of metal particles was performed by kneading with various solvent. The metal particles obtained from the surface treatment were kneaded, diluted and dispersed to make paint, and it was used to form paint films. The dispersion state and magnetic properties of metal particles were studied.
Considering the results of SEM observation, glossiness and measurement by STM and XMA, the state of dispersion was clarified. It was found that surface treatment of metal particles obtained well-dispersed state of the particles, and magnetic tape with high magnetic property (magnetic retentivity) was formed. From the results, it was indicated that surface treatment of metal particles is effective on production of highgrade videotape.View full abstractDownload PDF (4948K) -
Yoshimi Takahashi, Iwasaki Kazuharu1993 Volume 40 Issue 9 Pages 863-866
Published: September 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSBonded soft ferrite has been expected for many applications because of its low cost and well adaptability for the complicated shape. However, since the effective permeability is too low due to the mixture of ferrite powder and resin, the remaining problem is to enhance the permeability. So, the present study is to establish a method to estimate the induction together with the permeability of the powder material and to effectively investigate bonded soft NiCuZn ferrite materials. As a result, it has been found that the sintering temperature of the ferrite powder is essential to attain high inductance, and the broader distribution of pariticle size of ferrite powder results in the higher inductance.View full abstractDownload PDF (1326K) -
Kazuharu Iwasaki, Hitoshi Shimomuki, Ken Hosoya, Hiroshi Ito1993 Volume 40 Issue 9 Pages 867-870
Published: September 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSBonded soft ferrite using the injection molding has been expected for many applications because of low cost and complicated shape. However, the effective permeability of it is too low because of the mixture of ferrite powder and resin to have to be increased for its applications.We produced bonded soft ferrites mixed with nylon resin and several kinds of NiCuZn ferrite powders whose inductance was different by the kneading and injection molding. We got the high fludity ferrite compound by trying to make additional quantity of nylon resin and lubricant most suitable. So, we could increase the ferrite powder composition in it, and develop the bonded soft ferrite whose permeability μ' is equal to 30 at frequency 1kHz.View full abstractDownload PDF (1332K) -
Koichi Kakizaki, Hiroyuki Sano, Minoru Fujita, Nobuyuki Hiratsuka1993 Volume 40 Issue 9 Pages 871-874
Published: September 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSAcicular barium ferrite particles in which the doping Co2+ ions and Ti4+ ions were substituted for Fe3+ ions have been prepared by the sintering method. The acicular BaCo0.7Ti0.7Fe10.6O19 particles which had coercivity of about 1 kÖe were mixed with a binder, then the resulting mixture was coated on a PET film under a magnetic field of 8 kÖe applied vertically to the surface of the film. The recording characteristics of the acicular barium ferrite magnetic tapes were measured by using commercially available open reel tape deck.
The output waveform of the acicular barium ferrite magnetic tapes showed that the tapes had the perpendicular magnetic anisotropy. However, the low packing density of the particles and the rough surface resulted in the low value of the signal output in the high frequency. Therefore, we attempted to improve the dispersion quality and the spacing loss. The signal output of the improved acicular barium ferrite magnetic tape was about 2 times as large as that of the previously prepared tape.View full abstractDownload PDF (2495K) -
Akihiro Makino, Yutaka Yamamoto1993 Volume 40 Issue 9 Pages 877-880
Published: September 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSMn-Zn ferrite with fine grains of about 2.1μ m in size was synthesized by sintering of hydrothermal-precipitated ferrite powders, and its core losses were evaluated. At room temperature, based on the dependence of frequency, the core losses of the ferrite at 0.2MHz to 2MHz with 50mT and at 0.5MHz to 5MHz with 5mT are smaller than those of the commercial ferrites with grains of 7.7 μ m to 10.9 μm in size. So, the core loss is 70% at 500kHz, 50mT and 50% at 1MHz, 5mT of that of the commercial ferrites, respectively. At 80°C, which is almost actual circumstance, the core loss of the ferrite is also smaller than that of the commercial ferrite at 0.5MHz to 1MHz. Therefore, the fine grain ferrite is expected to be useful as material for high-frequency transformer.View full abstractDownload PDF (1503K) -
Yutaka Yamamoto, Akihiro Makino1993 Volume 40 Issue 9 Pages 881-885
Published: September 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe Mn-Zn ferrite ceramics with high density above 99.8% and fine grain size below 5 μm have been obtained by sintering of hydrothermal-precipitated ferrite powders at lower temperature than that in the ordinary process. Mn-Zn ferrite ceramics with grain sizes below 3μm have relative permeabilities comparable to that of commercial one in a frequency range above 5MHz. The single side MIG heads composed of ferrite with fine grain(Gs=2.3μm) are manufactured. The output voltage of the heads composed of the developed ferrite are equal to those of the heads composed of the commercial ferrite. The asymmetry instabilities of the heads composed of the developed ferrite are almost equal to those composed of the single crystal Mn-Zn ferrite which seemed to be good for the asymmetry instabilities. Therefore, Mn-Zn ferrite with fine grain sizes and high density is expected to be useful as magnetic head material for high density recording.View full abstractDownload PDF (3131K) -
Naoyuki Okamoto, Yasuharu Miyoshi1993 Volume 40 Issue 9 Pages 886-889
Published: September 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSMagnetic and mechanical properties of sputtered FeA1Si films were investigated. High saturation flux density (Bs) of 14-15kG was obtained for films of 4.5-6wt%Al-5-6.5wt%Si-balance of Fe with soft magnetic properties. From the results of annealing temperature dependence of soft magnetic properties and internal stress (σ) of films, an optimum annealing temperature for superior soft magnetic properties and low σ was 600°C. There was little decrease in permeability of Mn-Zn ferrite on which the film deposited.View full abstractDownload PDF (189K) -
Jing-Feng Li, Akira Kawasaki, Ryuzo Watanabe1993 Volume 40 Issue 9 Pages 890-894
Published: September 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIt is well-known that solid solutions can be formed in SiC-AIN system over a wide range of composition. The formation of the solid solution during sintering is, however, not sufficient in usual elemental powder mixtures due to their low diffusion coefficients. In the present study, SiC-A1N powder mixtures were prepared by ball-milling for 1 to 300h and subsequent HIPing at 2073 to 2173K for 2h. The formation of solid solutions was found to be enhanced in fine-mixed powder mixture. Variation of the thermal and mechanical properties for the HIPed compacts was found to depend on the ball-milling time. When the ball-milling time was prolonged up to 100h, almost homogeneous solid solution was formed, and the intrinsic properties to the SiC-AIN solid solutions were obtained.View full abstractDownload PDF (2431K) -
Takashi Sakamoto1993 Volume 40 Issue 9 Pages 895-901
Published: September 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSWe studied the sintering behavior of No powder compacts with an addition of boride alloy powders and Ni powders. These boride alloys are CrB, TiB2 and WB which have high decomposition temperature. The results of this experiment are as follows:
1)Though relative densities of sintered No powder compacts with an addition of boride alloy powders slightly rise up, these boride alloy powders do not disintegrate at sintering temperature.
2)The liquid phase produces in matrices of No powder compacts with supplementary addition of Ni powder at sintering temperature and promotes the densification.
3)Two endothermic peaks in DTA curve denote points of liquid phases. We infer that the endothermic peak at low temperature side is the transient liquid phase, because the liquid phase produces temporarily at parts of the matrix in heating up to melting point. The other endothermic peak corresponds to the melting point of No powder compact.
4)WB alloy powder in No powder compacts with an supplementary addition of Ni powder decomposes at lower temperature than that of WB boride compound.View full abstractDownload PDF (5249K) -
Yoshihiro Tada, Teisuke Sato, Masanobu Ikoma1993 Volume 40 Issue 9 Pages 902-907
Published: September 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSA pseudo-HIP technique combined with self-propagating high-temperature synthesis (SHS) has been studied for synthesis and consolidation of titanium aluminides, starting from compacts of mixtures of elemental powders of titanium and aluminum. The environmental pressure applied by the pseudo-HIP is effective to prevent swelling and dimensional change during the SHS reaction, resulting in high density in consolidated products. Density increases with the increase in applied pressure and 92% of theoretical density is stably achieved over a pressure of 45MPa. The volume of open pores remaining in consolidated products reduces rapidly with the increase in pressure; for example, the volume fraction of open pores is 2.7% in a Ti-47at%Al aluminide reaction-synthesized under a pressure of 45MPa and this value is about one eighth of that in a sample reaction-synthesized without any pressure. The volume of closed pores remaining, however, is scarcely affected with pressure, keeping a volume fraction of about 10%. Non-equilibrium phases remaining in as-reaction-synthesized products can be changed into the equilibrium phases without any dimensional change of the products by annealing them at 1273K for an hour, and the consolidated samples show good ductility in compression tests at elevated temperatures above 1273K.View full abstractDownload PDF (401K) -
Seizo Takahashi, Takeo Nakagawa1993 Volume 40 Issue 9 Pages 908-913
Published: September 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDeep wall cup shaped compacts were formed by a uniaxial pressing tool, using dry and loose iron powder of controlled particle size distribution prepared by sieving and with the addition of 6μm carbonyl iron powder. The loose powder including 0.7wt% zinc stearate and 0.5wt% of liquid paraffin could be automatically filled into a cylindrical die cavity and formed by a single stepped punch. Avarage green density of formed compact reached a relative density of 90% and the variation in the density throughout a green compact was reduced to less than 2%. Sufficient flowability of the densified powder at the bottom was experimentally confirmed by investigating the change of the density distribution during compaction. It flowed into the cup wall above a certain compacting pressure. Radial crushing strength of the sintered cup wall amounted to 300 MPa.View full abstractDownload PDF (369K) -
Masatomo Kamada, Nobuyuki Nakamura, Hideto Goto, Youichi Tokunaga1993 Volume 40 Issue 9 Pages 914-918
Published: September 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSPhase constitution of Fe-8mass%Cr alloy at elevated temperatures and the relationship between phase constitution and sintering mechanism were investigated by means of the model examination of two twisted wires.
The ferritic structure of Fe-8mass%Cr alloy at room temperature easily transforms to full austenite during heating to elevated temperatures. The matrix, however, changes the structure from γ to (δ/γ) two phases in the temperature range of 1463-1523K and then to δ single phase above 1523K. During holding at the (δ/γ) two phases region, the δ volume fraction increases until 7.2ks and levels off after that, because the δ/γ ratio reaches the equilibrium state at a given temperature through the re-distribution of Fe and Cr atoms into δ and γ phases.
Sintering of two twisted wires in δ or γ single phase regions follows a linear relationship with a slope of 1/5 (m=5);log(x/a)=K+(1/m)⋅log(t), where x is neck width, a is wire radius, t is sintering time, K and m are constants. The slope 1/5 indicates that volume diffusion mechanism controls the sintering in single phase regions. On the other hand, the slope of the linear relationship in (δ/γ) two phases region becomes larger than 1/5 (m<5), because not only sintering but also γ phase decmmnnsit.inn occurs dnrine early st.aee of isothermal hnldine.View full abstractDownload PDF (3900K) -
Hao-Nien Huang, Teruhisa Watanabe1993 Volume 40 Issue 9 Pages 919-922
Published: September 15, 1993
Released on J-STAGE: February 08, 2011
JOURNAL FREE ACCESSIn a previous paper, the general equations on infiltration through one surface and all surfaces of a model sintered skeleton, based on a rectangular parallelopiped having same radius straight-cylindrical pores crossing at right angles on three dimensions in itself, were introduced, and examined experimentally with sintered iron skeletons and the water infiltrant. The equations obtained are as follows:
1) The general equation of infiltration through a single side of a skeleton is,
V=Pr⋅S1⋅(R⋅γLV⋅COSθ/18ηL)1/2⋅t1/2
where, V:volume of the liquid infiltrated(cm3), Pr:porosity of the skeleton, S1:infiltration area of the skeleton(cm2), γLV:surface tension of the liquid(g/s2), R: radius of the pore(cm), θ: contact angle between the skeleton and the liquid(deg), ηL:viscosity of the liquid(g/cm⋅s), t :infiltrating time(s).
2) The general equation of infiltration through all surfaces of the skeleton is,
V=Pr⋅SA⋅(R⋅γLV⋅COSθ/18ηL)1/2⋅t1/2
where, SA:2 (S1+S2+S3) [total surface area of the skeleton] (cm2).
In this report, it is found that both of the above equations also hold good at the first period of infiltration time in several experiments which are carried out with the sintered iron skeletons and the pure silver infiltrant.View full abstractDownload PDF (1476K) -
Hideshi Miura1993 Volume 40 Issue 9 Pages 923-934
Published: September 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSSintered ferrous materials normally contain irregularly shaped pores(10-20 vol.%) which reduce their mechanical properties compared with those of wrought materials. This work has, therefore, been carried out to produce high performance materials by improving the pore and matrix structures with conventional and advanced powder processing techniques.
At first, the evaluation of internal structures was attempted by measurement of Young's modulus which was found to be mainly affected by the porosity and the pore shape. Using the proposed pore shape factor (η), the relation between Young's modulus of sintered materials (E) and the porosity (ε) was able to be simply and successfully expressed as E/E0=(1-ε)/(1+ηε), where E0 is Young's modulus of bulk material. This rl was a suitable factor to evaluate the degree of spheroidizing of pores. Then the mechanism of sintering and spheroidizing of pores in each iron compact having a small addition of P, Si and S was investigated, and also the correlation between the spherical pores and the properties was studied. From the point of views of improving the matrix structure, a precisely controlled austemper heat treatment was applied to Si-Ni steel compacts and the properties of the same level as the sinter-forged steels were obtained. Finally, applications of Metal Injection Molding (MIM) process to various steel powders were performed, and the results indicated the attainability of very high performance sintered ferrous materials which will meet the requirement of heavy duty structural components.View full abstractDownload PDF (8475K)
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