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Volume 36, Issue 6
Displaying 1-36 of 36 articles from this issue
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[in Japanese]1989 Volume 36 Issue 6 Pages 632
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (70K) -
Kenji Suzuki1989 Volume 36 Issue 6 Pages 633-652
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSMechanical alloying(MA) and mechanical grinding(MG) using a ball mill have attracted much attention as a solid state amorphization process, which approaches thermodynamically from the opposite side against the conventional procedure of melt or vapor quenching. This article reviews the atomic-scale structure and property of NiZr, Ni2V3, Co5Y and 3BiFeO3-ZnFe2O4 amorphous solids prepared by MA and MG.View full abstractDownload PDF (698K) -
Kazuto Tokumitsu1989 Volume 36 Issue 6 Pages 653-657
Published: August 25, 1989
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSAmorphous Fe-Zr powders were prepared with the mecanical alloying method from Fe and Zr elemental powders. That amorphization process was investigated with X-ray diffraction and 57Fe Mbssbauer spectroscopy. The process was discussed with the three stages ; The first is the crushing stage that the crystalline X-ray diffraction patterns change to broad but the atomic alloying is scarcely observed. The second is the stage that the change of the patterns is stationary but the atomic alloying is advanced steadily-The third is the final stage introduced to the amorphous hallow patterns.View full abstractDownload PDF (3748K) -
Chung Hyo Lee, Mitsuhiro Mori, Uichiro Mizutani1989 Volume 36 Issue 6 Pages 658-661
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIntermetallic compounds NiZr and Cu5Zn8 with good and poor glass-forming abilities were subjected to mechanical grinding, MG, under Ar atmosphere. MG should involve a process which raises the free energy of the system and may result in amorphization. In order to study this process we estimated the enthalpy changes in the DSC measurement, which are considered to reflect the sum of the heat release due to crystallization of an amorphous phase and dissipation of the strain energy stored in ball-milling. A mixture of pure metal powders Cu and Ta was also chosen for this study, the binary system of which gives rise to a positive heat of mixing and, hence may involve the same energizing process as MG above mentioned. In NiZr and Cu30Ta7O, the DSC profile including the peak position and the area, is found to change with increasing milling time. On the other hand, Cu5Zn8 behaved in a different manner and the heat release only due to the dissipation of the strain energy is observed.View full abstractDownload PDF (182K) -
Hiroshi Kimura, Masayoshi Kimura1989 Volume 36 Issue 6 Pages 662-667
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe processing control based on the formation of multilayers and the kinetics of a solid state amorphizing transformation by mechanical alloying(MA) of Co85Zr15 is proposed, from which one can optimize the conditions for an efficient and high quality production of amorphous powders using a rotating-arm reaction ball mill with a relatively high rotational speed(R) above 400 rev min-1. For R=400 and 450 rev min-1, the use of a higher flow rate of cooling water(Cw) above 830 ?? h-1 leads to the occurence of a plateau of attrition tempeature, although it is short, prior to an exothermic reaction; this MA process is almost conducive to a two-stage amorphization with Johnson-Mehl-Avrami exponent(n) of n1=1.4 and n2=2.6. While, the MA with Cw<150 ?? h-1 without the plateau shows an apparently single value of n=2.0; this process is denoted as a mixed stage amorphization which includes the formation of a crystalline solid solution. A rotational speed change method consisting of the ball milling by the end of the plateau using R=300 rev min-1 and an exothermic reaction by MA using of 400<R<500 rev min-1 leads to the two-stage amorphization even for a lower Cw of 20 ?? h-1. With increasing R from 300 to 450 rev min-1, the amorphization rate is found to decrease. The activation energy for the amorphization of Co85Zr15 by MA using R=400 rev min-1 is derived as 2.0±0.5 eV; this value is slightly higher than 1.7 eV for with R=300 rev min-1.View full abstractDownload PDF (314K) -
An Analysis by Model SimulationHitoshi Hashimoto, Yong Ho Park, Ryuzo Watanabe1989 Volume 36 Issue 6 Pages 668-671
Published: August 25, 1989
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe motion of balls in a vibratory mill during mechanical alloying was analyzed by computer simulation using a one-dimensional model of milling process. The model consists of visco-elastic balls and a one-dimensional vessel which vibrates in the virtical direction. In this model, energy consumption by mechanical alloying of powder particles during impact of balls was considered as the energy loss by viscous resistance during impact of the visco-elastic balls. The impact force or the impact energy obtained by the simulation was related to the microhardness, crystallite size and lattice strain of the powder particles which were mechanically alloyed by vibratory milling.View full abstractDownload PDF (244K) -
Mechanical Reaction ProcessShuji Wanikawa, Tohru Takeda1989 Volume 36 Issue 6 Pages 672-676
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSTiC was synthesized by milling the mixture of Ti and C elemental powders in vacuum using the screw disc ball mill. The reaction was directly observed and the milling conditions to make TiC powders were clarified. Exothermic reactions during milling were occured at the milling time of 280-400, 70-94 and 16.6-17.8ks according to the disc rotational speed of 100, 200 and 400rpm, respectively. In all case, the amount of TiC as reaction products were of 92.5-93.0%.View full abstractDownload PDF (1229K) -
Yoshihiro Tada, Teisuke Sato1989 Volume 36 Issue 6 Pages 677-682
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThermit reaction and its use to dispersion strengthening of aluminum has been studied in mechanically alloyed Al-Fe3O4. Al-Cr2O3 and Al-MoO3 systems. Differential thermal analysis shows that thermit reaction occurs in Al-Fe3O4 at temperatures above 610°C, whereas reaction is not observed both in Al-Cr2O3 and Al-MoO3 at temperatures up to the melting point of aluminum (660°C). Dispersion strengthning by the thermit reaction products is studied in extrudates of the mechanically alloyed Al-Fe3O4 powder: annealing above 610°C brings out increases in hardness and tensile strength. lt is shown that thermit reaction in mechanically alloyed aluminum-metallic oxide composites is successfully applicable for dispersion strengthening of aluminum for elevated temperature services.View full abstractDownload PDF (1392K) -
Shouichi Ochiai, Yo Kojima, Chihiro Nakano1989 Volume 36 Issue 6 Pages 683-687
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSNiAl intermetallic compound, B2 type nickel-aluminide, is of particular interest because it combines good oxidation-resistance with a high melting point. In this study, NiAl alloys were produced by the mechanical alloying (MA) process for the purpose of refine-ment of microstructures. The MA was carried out in the attritor mill using pure nickel powder(4-7μm in diameter) and alloy powder (Ni-62.5at%Al, 43μm in average diameter) as starting materials. Mechanically alloyed powders were consolidated by the hot pressing. Changes of microstructures and mechanical properties during MA were investigated. MA proc-essing for longer periods produced the grain refinement and led to the formation of α-Al2O3 and Ni3Al phase in the NiAI matrix due to the oxidation of aluminum during MA. In the bending test for NiAl specimens produced under the condition of optimum MA processing time, the large deflection was obviously obtained above about 673K. Observing fracture surfaces, it was also found that the transition from a brittle cleavage fracture mode to a ductile fracture mode was caused by the application of the MA process even at the room temperature . These results are suggesting that MA process has good effect on the improvement of the ductility for NiAl.View full abstractDownload PDF (5661K) -
Teruo Takahashi, Yasuhiko Hashimoto1989 Volume 36 Issue 6 Pages 688-692
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe mechanical alloying was carried out using pure Cu, graphite and Ti or Zr, and the powders of solution or nanometer order composite in Cu-Ti-C and Cu-Zr-C systems obtained were consolidated by hot-isostatic-pressing, hot-forging, hot-pressing and/or hot-extrusion. The strength of the specimens prepared by hot-isostatic-pressing as-mechanically alloyed powders, followed by hot-forging at 1073 K were 294-412 MPa, and their values of elongation were 2-4 %. The specimens prepared by hot-pressing at 1273 K, and the specimens prepared by hot-isostatic-pressed at 1073 K after canning the powders heat-treated at 1073K for 3.2 ks, followed by hot-forging at 1073 K were relatively high strengh of 510-560 MPa, however, their values of elongation were 3-5 %. The strength of the specimens prepared by hot-extrusion at 1073 K were 657-725 MPa, and their values of elongation were 11-12 %, they were very strong and ductile.View full abstractDownload PDF (3925K) -
Hiroki Esaki, Haruhiko Sugimoto, Kei Ameyama, Masaharu Tokizane1989 Volume 36 Issue 6 Pages 693-698
Published: August 25, 1989
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe mixture of elemental powders of (1) Ti(50at%)-Al(50at%), (2) Ni(76at%)-Al(24at%) and (3) Ti(50at%)-Ni(50at%) were offered to the mechanical alloying (MA) process. The ultra-fine grained (average grain diameter <0.2μm) compacts consisting of (TiAl+Al 3Ti), Ni 3 Al and (TiNi+Ni 3Ti) intermetallic compounds were obtained by vacuum hot pressing (at 1173-1223K) of MA processed powders of (1), (2) and (3), respectively.
Since the MA processed powder of (3) indicated amorphous state, it was also offered to the vacuum warm pressing at 723K (bellow crystallization temperature) under 1300MPa. The compact was produced in an amorphous state.View full abstractDownload PDF (5458K) -
[in Japanese]1989 Volume 36 Issue 6 Pages 700
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (79K) -
Hidenori Kuroki, Masayoshi Nishio, Chieto Matsumoto1989 Volume 36 Issue 6 Pages 701-706
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDimensions were measured on 52at%Ni/48at%Ti mixed powder compacts at several stages through the process of pressing and sintering to know how to make precision NiTi parts in a convensional powder metallurgical process. The cubic compacts 5mm in size were pressed under 200-800MPa, heated up in argon at the rates of 2K/min or 5K/min or through the 10K/min-2K/min-10K/min program, and held at 1323K for 60min.
Slower heating in the exothermic reaction temperature range resulted in lighter deformation. The dimensional change was found to be anisotropic. Compacts were observed to expand to reach a peak value and then shrink. This change proceeded earlier in the compacting direction than in the lateral direction. For the compacts pressed at 800MPa, the final dimensional change was shrinkage in the compacting direction and expansion in the lateral direction.View full abstractDownload PDF (1622K) -
Yoshikazu Suzuki, Katsuyoshi Shimokawa, Hidero Unuma1989 Volume 36 Issue 6 Pages 707-711
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSA Ni-Ti compact underwent an exothermic fusion reaction during quick heating in a vacuum pressure. Consequently. the phenomena resulted in the purification of the alloy. The application of this technology will simplify the manufacturing process and facilitate quality control of the product. The authors researched the effect of heating rates. vacuum range and gaseous atmosphere on the exothermic fusion reaction in detail. and arrived at the optimum conditions for the reaction. Moreover. porous semi-fused Ti-Ni alloy was produced by the exothermic reaction, under vacuum conditions in a closed silica tube.
The Ti-Ni alloys obtained by the exothermic reaction showed mechanical properties comparable with a commercial alloy.View full abstractDownload PDF (2717K) -
Hiroyuki Nakanishi, Isao Tanaka, Taira Okamoto, Yoshinari Miyamoto, Os ...1989 Volume 36 Issue 6 Pages 712-715
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDense TiC-Ni composites were fabricated by a new process of the gas-pressure combustion sintering. They were synthesized and simultaneously densified over 98% of theoretical from the mixed elemental powders under the Ar gas pressure below 100 MPa. The addition of Ni and TiC powders could reduce the high reaction heat and hence lead to control the grain growth in the sintered body. Some model samples of the functionally gradient materials for the TiC-Ni system were fabricated to demonstrate that the gas- pressure combustion sintering is an efficient process to develop such new high temperature materials.View full abstractDownload PDF (922K) -
Hideshi Miura, Tadatoshi Honda, Tomofumi Watanabe1989 Volume 36 Issue 6 Pages 716-722
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSTi has merits as a strong solid solution hardener and a sintering enhancer for iron. In this study, transient liquid phase sintering has been applied to the Fe-Ti system for forming the high performance iron powder metallurgy materials with considering several third additive elements. Specimens were prepared from an atomized iron powder(-100mesh), Ti powder (-350mesh) and various alloying element powders such as Co, Ni and Si, followed by compacting under 686MPa and sintered at 1573K for 3.6ks in vacuum.
A 6% addition of Ni to the Fe-4%Ti system showed greater than a 85% increase in tensile strength and hardness, although elongation was decreased with increasing Ni content. This is attributed not only to the solid solution hardening by the uniform distribution of Ti and Ni but also to the spheroidization of pores. On the other hand, tensile strength of the Fe-Ti-Si systems increased with an increase in Si content, independing on Ti content as a result of forming the Ti rich intermetallic compound particles such as SiTi3 and Si3Ti5. Generally, addition of third alloying elements to the Fe-Ti system reduced the ductility, but only Co showed no influence on that because of remarkable enhancement of the sintering of Fe-Ti compacts.View full abstractDownload PDF (8215K) -
Masato Ohtsuki, Tohru Kohno1989 Volume 36 Issue 6 Pages 723-726
Published: August 25, 1989
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSEffects of addition of sintering aids on sintering of aluminum, Al-Si-Cu-Mg-Fe alloy and aluminum bronze were investigated. The addition of AlF3-KF is effective in case of aluminum sintering but not effective in case of Al-Si-Cu-Mg-Fe alloy. It is considered that the surface oxide of the powder is removed by the eutectic reaction with the sintering aids for aluminum, but that the formation of high melting MgF2, which is the reaction product of KF and Mg, prevents the sintering of Al-Si-Cu-Mg-Fe alloy. The addition of AlF3-KF was found to reduce the sintering temperature for aluminum bronze although AlF3 alone is an effective sintering aid.View full abstractDownload PDF (1449K) -
Hideyuki Okinaka, Reiko Ueno, Hiroko Kumazaki, Hiromichi Mitsuda1989 Volume 36 Issue 6 Pages 727-730
Published: August 25, 1989
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSSintering temperature of BaTiO3 is reduced by addition of LiF, increasing the Ba/Ti ratio and decreasing the starting particle size of BaTiO3. Li and F are contained not only in BaTiO3 grains, but also in grain baundaries. The quantity of them decreased by increasing firing temperature, because of vaporizatin of LiF, and also is dependent on the Ba/Ti ratio which affects the reaction mechanism in firing process.View full abstractDownload PDF (3351K) -
Shigeyuki Somiya1989 Volume 36 Issue 6 Pages 731-735
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (194K) -
Mamoru Mitomo, Syunsuke Ono1989 Volume 36 Issue 6 Pages 736-739
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSSilicon oxynitride (Si2N2O) ceramics were fabricated from equi-molar mixtures of Si3N4 and SiO2 with 5 wt % Al2O3 as a sintering aid by heating at 1650-1950°C for 1 h in 980 KPa N2. The initial stage of densification was due to the solution and repreci-pitation of Si3N4 through a liquid phase of SiO2-Al2O3 system. At>1750°C, further densification took place accompanied by Si2N2O formation and anisotropic grain growth. The thermal decomposition of Si2N2O at the surface of compact lowered the density at>1850°C. The stability of solid phases under sintering conditions was discussed in relation to calculated SiO partial pressures on solids.View full abstractDownload PDF (1224K) -
Jing-Feng Li, Ryuzo Watanabe, Akira Kawasaki1989 Volume 36 Issue 6 Pages 740-745
Published: August 25, 1989
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSCeramic alloys were synthesized by reaction sintering and densified by HIP in the temperature range of 2070 to 2120K under a pressure of 200MPa. The starting powders were commerical silicon nitride, aluminium nitride and graphite powders. A small amount of calcia was added in the form of Ca(NO3)2⋅4H2O, and the reaction sintering was performed in a nitrogen atmosphere in the temperature range of 1670 to 2170K. The reaction process was investigated by X-ray diffraction analysis and found to be consisted of two steps: the formation of α-sialon and its carbothermal reduction. When AIN content was less than 35mol%, a uniform 2HSiC-AIN solid solution was formed with fine grain size of about one-third of that of the strating powders. On the other hand, when more AIN powders was added, two-phase composite was formed. Complete densification of the synthesized compact was attained by HIP treatment.View full abstractDownload PDF (5250K) -
Atsushi Nakahira, Yoshiaki Fukushima, Koichi Niihara1989 Volume 36 Issue 6 Pages 746-751
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSEffects of SiC and ZrO2 dispersions on the microstructure, fracture toughness and strength were investigated for Al2O3-SiC-ZrO2 composites. The Al2O3-SiC-ZrO2 composites were prepared by hot-pressing the mixtures of fine Al2O3, SiC and ZrO2 powders. Transmission electron microscopic observation indicated that finer ZrO2 particles were dispersed mainly, within Al2O3 grain whereas large ZrO2 grains were located at the grain boundary of Al2O3 and most of SiC particles were dispersed within Al2O3 grains and large ZrO2 grains. The fracture toughness and strength of this composites were greatly enhanced by incorporating the ZrO2 and SiC particles into Al2O3. The toughening and strengthening mechanisms of Al2O3-SiC-ZrO2 composites were discussed.View full abstractDownload PDF (2337K) -
Hitoshi Sumiya, Kazuo Tsuji, Shuji Yazu1989 Volume 36 Issue 6 Pages 752-755
Published: August 25, 1989
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSSingle phase sintered compact of cBN (polycrystalline cBN) may be prepared under high pressure and temperature (>5.2GPa, >1350°C) from hBN compact carrying a small amount of Mg3BN3 as a catalyst. This work investigated the influence of the amount of Mg3BN3 added to the hBN compact on the microstructure and the thermal conductivity of the prepared polycrystalline cBN. It was established that by controlling the amount of Mg3BN3 (-1.0mol%) it was possible to prepare polycrystalline cBN which had a high thermal conductivity, approximately 6W/cm°C at room temperature. In addition, it was found that a small amount of water diffused into the hBN compact containing Mg3BN3 would suppress abnormal growth of cBN particles. Thus, by adding 0.2wt% of water to the hBN compact containing 1.0mol% of Mg3BN3, a homogeneous cBN sintered compact having regular particles (5-8μm) and with high thermal conductivity (-7W/cm°C) could be consistently prepared.View full abstractDownload PDF (3796K) -
Hideaki Itoh, Hisaaki Takao, Hiroyasu Iwahara, Tsuneaki Matsudaira, Sh ...1989 Volume 36 Issue 6 Pages 756-758
Published: August 25, 1989
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSComposit sintered compacts of the cBN-diamond system were prepared at 7 GPa and 1700°C for 30 min by reaction sintering of the starting powder composed of hBN and diamond. A high conversion yield from hBN to cBN was attained by adding 1 wt% NH4NO3 as a catalyst. An induced transformation from hBN to cBN occurred on the surface of the added diamond seed crystals. The sintered compact prepared from the starting powder having the composition of 70 wt% hBN - 30 wt% diamond, showed a relative density of 99% and an average Vic-kers microhardness of 5100 kg/mm2, which suggested the formation of direct bonding between the transformed cBN grains.View full abstractDownload PDF (1408K) -
[in Japanese]1989 Volume 36 Issue 6 Pages 760
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (46K) -
Kimiyoshi Goto1989 Volume 36 Issue 6 Pages 761-769
Published: August 25, 1989
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSSmall particles of ferromagnetic BaO⋅Fe2O3, SmCo5, SM2Co17 and Nd2Fe14B compounds were prepared by the circumspect powder metallurgical method, and behaviours of their magnetic domains were studied with the decrease of the particle size.The colloid-SEM method invented by the present author was effectively used to observe domains of small particles less than 10 μm in size. With the decrease of the particle size the number of domains in one particle decreases, and finally the single-domain state is found for each compound, as expected by the theories. The critical size for single-domain particles, which is defined by the upper limit of the particle size range where the single-domain state can exist, is successfully estimated for all the above compounds from the particle size distribution curve of many single-domain particles, and obtained values of the critical sizes of the compounds are compared with the theoretical ones.View full abstractDownload PDF (5353K) -
Masaaki Okubo, Hiroshi Ozaki, Yukio Ishibashi, Shuzo Oshima, Ryuichiro ...1989 Volume 36 Issue 6 Pages 770-773
Published: August 25, 1989
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSA new method to measure the velocity distribution of magnetic fluid flows using optical fibers and laser beam was developed. In this method, the local velocity of the magnetic fluid was obtained by measuring the time taken for a tracer particle to pass between two sets of fibers. After this method was adjusted with the rotational flow in a rotating channel, it was applied to the flow of a magnetic fluid in a circulation channel excited by a travelling magnetic field made by a stator of a single-sided linear induction motor. From the measurements, the induced velocity was found to be proportional to the frequency and the strength of the applied current to the inductor. It was important to choose the size of tracer particles, the wavelength of the light source and the sensitive optical detector for better results.View full abstractDownload PDF (293K) -
Hiroshi Nagai, Kazuhiko Majima, Masaru Yokota, Tetsuya Sawayama, Takeh ...1989 Volume 36 Issue 6 Pages 774-777
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSMetallic magnetic fluids containing Fe, Co or FeCo alloy ultrafine particles were prepared by vacuum evaporation method, and then the magnetic properties and particle sizes of magnetic fluids were studied. Magnetic fluids with alloyed Fe-Co particles were obtained by evaporating the mixed Fe and Co raw powders in vacuum onto the oil with surfactant. The particle sizes were in the range of 30Å to 35Å. In order to control the particle size Ar gas was introduced into the chamber and magnetic fluids were prepared at various pressures. The particle sizes in the fluids were increased from 30Å to 80Å with Ar pressure.
We also attempted to obtain a metallic magnetic fluid by arc-plasma method in Ar-H2 atmosphere. The ultrafine particles were collected into the oil successfully with venturi scrubber, but further research is needed to generate smaller particles in order to obtain stable colloids.View full abstractDownload PDF (3701K) -
Basic Study to Prepare the magnetic Fluid Using Colloidal Ferromagnetic MetalsToyohisa Fujita, Balachandran Jeyadevan, Mitsuo Mamiya1989 Volume 36 Issue 6 Pages 778-781
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSUltrafine iron particles were prepared by the reduction of ferrous salts with aqueous sodium borohydride in the presence of surfactant. Particles of about 100Å were observed with an electron microscope among the iron particles prepared in the presence of sodium oleate or duomeen-TDO. When the concentration ratio of oleate to ferrous ion increased in the vicinity under critical micelle concentration of oleate, FWHM (full width at half maximum) in the reflection of the (110) plane by x-ray diffraction, the specific surface area and adsorbed amount of oleate, of resultant α-iron increased. Also, remanent magnetization and coercive force decreased with the increase of concentration ratio of oleate to ferrous ion in the reactive solution. The results mentioned above supposed the decrease of iron particle size. However, a stable iron particle suspension could be prepared, if thickness of adsorbed surfactant layer is increased.View full abstractDownload PDF (1374K) -
[in Japanese], [in Japanese], [in Japanese], [in Japanese]1989 Volume 36 Issue 6 Pages 782-785
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSColored water-based magnetic fluid (red, yellow, blue and black) are obtained by mixing magnetic fluid with dye solution. Red and yellow magnetic fluid contain Mg-Zn ferrite particles, and blue and black contain Mn-Zn feriite particles. These ferrite particles are obtained by hydrothermal synthesis. These particles covered with mono-molecular adsorption layer of oleic ions is stably dispered in suitable concentration of sodium dodeccylbenzenesulfonate solution. For the purpose of using under the same magnetic field, thier magnetization intensities are adjusted to about 1.4 emu/g under the 8 k0e magnetic field, then the reflected color of each magnetic fluid painted on a white paper is close to that of dye solution. Transmitted color of each fluid becomes also very bright. Viscosity of each colored magnetic fluid mentioned above is less than 2 cp.View full abstractDownload PDF (237K) -
Yasushi Ido, Takahiko Tanahashi1989 Volume 36 Issue 6 Pages 786-789
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSConstitutive equations for conducting magnetic fluids have been studied by some researchers, but their equations cannot express the phenomena of conducting magnetic fluids perfectly because they have some defects, for example, some did not satisfy the principle of frame-indifference and not consider with viscoelastic effect. We suggest a new way of determination of constitutive equations for conducting magnetic fluids to formulate the theory that former defects are improved. That is the method which is a combination of the theory of integrity bases and the principle of maximal dissipation rate. The constitutive equations we obtain only include the terms which allowed by thermodynamics and satisfy the principle of frame-indifference. Furthermore, not only for compound process but also for complex process, we can obtain the nonlinear constitutive equations for conducting magnetic fluidsView full abstractDownload PDF (222K) -
Yasushi Ido, Yoshiatsu Oki, Takahiko Tanahashi1989 Volume 36 Issue 6 Pages 790-793
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSPower expended theorems have been used mainly for structure analysis in the field of material science. These theorems have been constracted on the standpoint of statics, so they cannot treat dissipative phenomena. In this paper, we consider dissipative effects and give a power expended theorem for conducting magnetic fluids with internal rotation for the first time. On this way, we assume that magnetic fluid is incompressible and suspended particles rotate rigidly, and we derive the theorem being based on the kinematic balance equations which we obtained in the previous reports. Developing this theorem, we will expect to obtain some useful informations about flow fields and electromagnetic fields, especially about electromagnetic pressure.View full abstractDownload PDF (179K) -
Kunio Shimada, Shinichi Kamiyama1989 Volume 36 Issue 6 Pages 794-798
Published: August 25, 1989
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe investigation of oscillatory flow of a magnetic fluid in a circular tube in a nonuniform magnetic field as a special case of the unsteady flow is made. It is one of the basic study on the development of damper or actuator using a magnetic fluid. Experimental study is made on the characteristics of pressure fluctuation to the given oscillatory flow. On the other hand, the theoretical analysis is made by using the equation of incompressible fluid. The experimental data are compared with the theoretical analysis, and the result shows that there is a large influence of the agglomerate of magnetic particles in a magnetic field on the resistance of oscillating flow of magnetic fluid.View full abstractDownload PDF (244K) -
Yoshimoto Odagawa, Katsuhiko Wakayama1989 Volume 36 Issue 6 Pages 799-802
Published: August 25, 1989
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSWith highly developed electronic instruments abounding and an avalanche of information being communicated these days, the need for sensors is increasing. Sensors are needed, among others, in the place where safety or security is prerequisite and for systems where they are needed to attain particular purposes required for each system. We developed a Tilt Switch using Magnetic Fluid. It detects an angle of tilt with high accuracy and reliability. Conventional tilt switches were mainly a mercury applied type or a mechanical type. This Tilt Switch is made possible by magnetic ally levitating using the metallic magnetic fluid developed by our own technology. The movement and tilt of the levitated metallic magnetic fluid provides a switching function.Our metallic magnetic fluid has excellent characteristics. It has high flux density resulting in strong magnetic levitation and its flux tends to be concentrated making it possible to detect tilt angle with high sensitivity and accuracy.View full abstractDownload PDF (217K) -
Hiroshige Kikura, Takahiko Tanahashi, Lee-Soo Seo1989 Volume 36 Issue 6 Pages 803-806
Published: August 25, 1989
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe present paper describes sloshing phenomena in a rectangular tank and a cylindrical tank which is horizontally oscillated under non-uniform magnetic fields. In the rectangular tank, the resonant frequency of magnetic fluids based on a potential theory are in good agreement qualitatively with that of experimental results. It is found that resonant frequency depends on the magnetic fields intensity and moves into high frequency region. In the cylindrical tank, instability of singular point of the swirling motion is discovered. Harmonic wave motion, swirling waves, flow pattern of surface waves and the region of swirling point are influenced by the intensity of the magnetic fields .View full abstractDownload PDF (248K) -
Naohiko Yamashita, Katsuto Nakatsuka1989 Volume 36 Issue 6 Pages 807-810
Published: August 25, 1989
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSIt is known that a thermomagnetic convection is caused when a temperature-sensitive magnetic fluid is heated under a non-uniform magnetic field, One of the authers reported that the efficiency of heat transfer from metal surface into the magnetic fluid was remarkably improved by applying a magnetic field.
In this study the effect of magnetic field on the cooling of temperature-sensitive magnetic fluid is examined using a double tube heat exchanger in which a high temperature magnetic fluid and cooling water are flowing in opposite direction, It is confirmed that cooling rate of the fluid increases with increasing magnetic field.View full abstractDownload PDF (202K)
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