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Volume 39, Issue 11
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[in Japanese]1992 Volume 39 Issue 11 Pages 936
Published: November 15, 1992
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (76K) -
Yuji Kaneko, Atsushi Hamamura1992 Volume 39 Issue 11 Pages 937-947
Published: November 15, 1992
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSBasic investigation on mechanisms of high densification, grain growth control and high-preferred orientation of Sr-ferrite sintered compact in the production process are performed. The high performance magnet has the composition of SrO⋅5.9Fe1O3, which is slightly deviated from that of the stoichiometric Sr-ferrite.CaO and SiO2 additives play important roles in the rapid densification and the grain growth control in the sintering process of Sr-ferrite compacts. The densification of the Sr-ferrite compact containing GaO and SiO2 additives is promoted by the presence of low melting liquid phase of the CaO-SiO2-SrO⋅6Fe2O3 system in the grain boundaries. The addition of small amount of SiO2, which is added to the raw material powder before calcining, can control the grain growth of Sr-ferrite particles and increase the intrinsic coercivity (iHc).In the presence of CaO additive, the SiO2 impurity causes the liquid phase sintering during the sintering process. The Al2O3 additive increases He by forming a solid solution with Sr-ferrite. In order to obtain higher degree of orientation, an improved parallel magnetizing circuit having uniformly distributed magnetic field strength is newly developed. By the analysis of the compressing mechanism of the Sr-ferrite fine particles, it is revealed that the preferred orientation process of the particles through the pressing in parallel magnetic field are considerably influenced by the average particle size and the particle size distribution. Based on these results, the highest quality magnets in current use are manufactured with high cost performance.View full abstractDownload PDF (6445K) -
Yuji Kaneko, Kunio Kitajima, Nobuo Takusagawa1992 Volume 39 Issue 11 Pages 948-952
Published: November 15, 1992
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSTo improve coercivity of Sr-Ferrite permanent magnet produced with additives of CaO and SiO2, effects of SrO and Cr2O3 additives on sintering behaviors and magnetic properties of sintered Sr-Ferrite were investigated. SrO addition was effective on dencification of Sr-Ferrite powder. This seemes to be caused by the fact that SrO additive increased the amount of a liquid phase which totally surrounded fine particles of Sr-Ferrite. Cr2O3 addition increased coercivity of Sr-Ferrite at the initial stage of the sintering process. Probably, the Cr2O3 additive interfered grain growth and increased magnetocrystalline anisotropy of Sr-Ferrite by replacing a part of Fe with Cr. Thus, the simultaneous addition of SrO and Cr2O3 to Sr-Ferrite containing CaO and SiO2 has enabled production of the sintered Sr-Ferrite magnets having high coercivity.View full abstractDownload PDF (3494K) -
Yuji Kaneko, Kunio Kitajima, Nobuo Takusagawa1992 Volume 39 Issue 11 Pages 953-958
Published: November 15, 1992
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSEffects of CaO and Si02 additives on the sintering phenomena of SrO⋅6Fe2O3 powder were clarified through investigating dependence of density, electrical specific resistivity and microstructure on sintering temperatures. In the case of densification of SrO⋅6Fe2O3 with no additives, unfavourable grain growth occured due to the solid-phase sintering. On the other hand, rapid densification as well as inhibition of grain growth was achieved by the addition of CaO and SiO2, where the liquid phase appeared above 1373K. Electrical specific resistivity of SrO⋅6Fe2O3 spec-imens varied, corresponding to the sintering stage. Especially, the value of electrical specific resistivity decreased sensitively in accordance with temperature range for the appearance of liquid phase formed from CaO-SiO2-SrO⋅6Fe2O3 system. SiO2 add-itive content against CaO had also remarkable influences on the value of electrical specific resistivity and microstructure of sintered SrO⋅6Fe2O3.View full abstractDownload PDF (3612K) -
Hitoshi Taguchi, Fumihiko Hirata, Taku Takeishi, Yuichi Yokoyama, Teru ...1992 Volume 39 Issue 11 Pages 959-963
Published: November 15, 1992
Released on J-STAGE: July 12, 2010
JOURNAL FREE ACCESSSubmicron sized particles of M-type Sr-ferrite were obtained from fine Fe2O3 and precipitated SrCO3. The particles with the size smaller than 1.0μm were observed by SEM, and the average size was about 0.3 μm. The magnetic properties of the powder were σs=7lemu/g and HcJ=5.5kOe. By means of dry vibrating milling, HcJ of the powder was reduced to 40% of initial value, aild the temperature dependence of Hcj (ΔHcJ/ΔT) was also reduced to less than 30%. Lattice distortion value of the milled powder was investigated by XRD. Lattice strain as well as crystallite size were calculated respectively using the method of Warren and Averbach. It was found that the strain of (206) plane is closely related to HcJ of the powder.View full abstractDownload PDF (1381K) -
Kunio Okimoto, Hiroshi Mizue, Masaru Yamaguchi, Tomio Satoh, Masayuki ...1992 Volume 39 Issue 11 Pages 964-969
Published: November 15, 1992
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSA magnetic composite material is fabricated by rolling. Anisotropic strontium ferrite powder, Zn-22Al superplastic powder and synthetic rubber are mixed with various mixing ratio and then kneaded. The kneaded compact is rolled at temparature ranging from 50°C to 120°C. It is investigated with regard to fabrication factors such as rolling reduction, rolling temperature, mixing ratio of ferromagnetic powder and Zn-22Al superplastic one, and addition of calcium stearate on characteristics of the magnetic composite material.
The magnetic comosite material imparts flexibility under load. It is found that the optimum forming conditions are a reduction of approximately 90% and a rolling temperature of 80°C Residual flux density of the magnetic composite material almost reaches the theoretical value for a given ferrite content per unit volume. This means that orientation of the ferromagnetic powder is accomplished almost completely.View full abstractDownload PDF (3249K) -
Kunio Okimoto, Masaru Yamaguchi, Tomio Satoh, Masayuki Watanabe, Nanao ...1992 Volume 39 Issue 11 Pages 970-976
Published: November 15, 1992
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSFerromagnetic strontium ferrite powders are mixed and then kneaded with pyrolytic binder which is made of ethylene vinyl acetate, acrylic polymer, paraffin wax and stearic acid for metal injection molding. The kneaded compacts are formed in a magnetic field at temperature ranging from 100°C to 165°C. After orientation of the magnetic powders by the magnetic forming, the pyrolytic binder is eliminated by heating up to 600°C and then the compacts are sintered at 1200°C. Effects of the processing factors such as magnetic field strength, forming temperature, relationship between applied direction of the magnetic field and forming direction are investigated on magnetic characteristics of the compacts. The results obtained are as follows:
(1) Residual flux density of the sintered compacts reaches 4400G., which corresponds to 94.6% of theoretical one.
(2) The forming temperature is proper above 135°C, and the effect of the pyrolytic binder is not exhibited below this temperature. This temperature corresponds approximately to flow value of 0.02m1/s in kneaded compacts.
(3) Magnetic characteristics of the sintered compacts made by pressing parallel to the magnetic field is superior to that made by pressing normal to the magnetic field.
(4) Maximum shrinkage of the sintered compacts occurs in the direction of the application of the magnetic field and is unaffected by the pressing direction.View full abstractDownload PDF (2855K) -
Noboru Ichinose, Isao Kaneda1992 Volume 39 Issue 11 Pages 977-980
Published: November 15, 1992
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSEffects of crystallization and nitrogenation on permanent magnetic properties have been investigated in the Sm2Fe17 alloy. It has been shown that the high nitrogen gas pressure of several 100kgf/cm2 is effective for nitrogenation of Sm2Fe17 powder which has an appropriate particle size. The nitrogenated compound Sm2Fe17Nx, under condition of several 100kgf/cm2 in N2 atmosphere has a saturation magnetization of 145emu/g. This value is smaller than that of literature one (160emu/gr) because of impurities of O2 and Fe.View full abstractDownload PDF (192K) -
Tatsuo Fujii, Masakatsu Sakamoto, Mitsuhiro Asano, Tokuro Nanba, Akiyo ...1992 Volume 39 Issue 11 Pages 981-984
Published: November 15, 1992
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESS(111)- and (100)-oriented Fe3O4 films were epitaxially formed on a-A12O3(0001) and MgO(100) single-crystalline substrates, respectively, by reactive evaporation method. The formation ranges of the epitaxial Fe304 films were determined as a function of substrate temperature, oxygen partial pressure, and a deposition rate. Their crystalline qualities were examined by various methods such as X-ray diffraction, RHEED and resistivity mesurements. A lattice mismatch of about 0.3% between Fe3O4 and MgO was very small. Then the film deposited on MgO seemed to have a good crystallinity and a smooth surface. Moreover the Verwey transition was clearly detected by a resistivity mesurement at about 110K. The transition temperature was nearly consistent with that of the bulk, indicating a good stoichiornetry of the sample film.View full abstractDownload PDF (1376K) -
Masakatsu Sakamoto, Mitsuhiro Asano, Tatsuo Fujii, Tokuro Nanba, Akiyo ...1992 Volume 39 Issue 11 Pages 985-988
Published: November 15, 1992
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESS(111)- and (100)-oriented Fe3O4/MgO superlattice films were prepared on α-Al2O3 and MgO single crystalline substrates, respectively. The artificial modulation periods estimated from the satellite positions of the X-ray diffraction peaks were in good agreement with the designed ones. Magnetization curves at room-temperature could be decomposed into an easily saturated component and a linear component proportional to the applied magnetic field. With decreasing temperature the magnetization increased rapidly below 20K, just like superparamagnetizm. The saturation magnetization at 5K was nearly consistent with that of the Fe, 04 bulk. The Mossbauer spectrum at room-temperature consisted of a pair of magnetic components assigned to iron ions located on the Fe3O4 lattices. But the magnetic hyperfine fields of both components were a little suppressed, compared with those of the Fe3O4 bulk. Magnetic spins at about 20A-thick interface regions of each Fe3O4 layer seem to be thermally fluctuated at room-temperature.View full abstractDownload PDF (259K) -
Nobuyuki Hiratsuka, Tetsuo Kadoshima, Minoru Fujita, Mitsuo Sugimoto1992 Volume 39 Issue 11 Pages 989-992
Published: November 15, 1992
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSCobalt ferrite thin films were prepared at substrate temperature(Ts) ranging from room temperature to 300°C by the targets facing type of sputtering. All the as-deposited films were composed of oxides and metals. When films were sputtered at Ts=150°C or below, they were mainly composed of oxides. When films were deposited at Ts=200°C or above, they were mainly composed of metals. The magnetization(M) of the latter was twice as large as that of the former. However, and films had in-plane magnetic anisotropy, and small values of Hc.
The cobalt ferrite thin films, which were deposited at Ts=150°C or below, with perpendicular magnetic anisotropy were obtained by means of the annealing at 300°C in air. This was caused by the shape magnetic anisotropy with columnar structure as well as the magnetocrystalline anisotropy of CoFe2O4. The Faraday rotation of the annealed films were smaller than that of as-deposited ones, because the surface of the annealed films became rough. The film which was prepared at Ts=100°C and was annealed at 300°C had the perpendicular magnetic anisotropy, and its magnetic characteristics: M=177emu/cc, Hc =1.51kOe and Sq=0.45(corrected squareness ratio=0.71). The Faraday rotation angles of the film had the maximum value of 3.67deg./μm.View full abstractDownload PDF (1232K) -
Nobuyoshi Komachi, Tatsuru Namikawa, Yohtaro Yamazaki1992 Volume 39 Issue 11 Pages 993-995
Published: November 15, 1992
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThin films of cobalt-cobalt oxide were prepared by reactive evaporation, and their magnetic properties were measured. The perpendicular magnetic anisotropy of the films were changed by the oxygen pressure and deposition rate. When the deposition rate was kept constant, the content of cobalt oxide in the film increased and a perpendicular magnetic anisotropy appeared with increasing oxygen pressure. The deposition rate also affected the content of cobalt oxide in the films because the number of the collisions between cobalt and oxygen molecules on the substrate changed. The films deposited at high deposition rate tended to have a longitudial magnetic anisotropy in spit of the high ratio of oxide in the films.View full abstractDownload PDF (167K) -
Teruyoshi Hirano, Eiju Komuro, Hiroki Hotaka, Tatsuru Namikawa, Yohtar ...1992 Volume 39 Issue 11 Pages 996-998
Published: November 15, 1992
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIron garnet thin films containing large amount of Bi were prepared by sputtering method, and their thermal stability has been investigated. Firstly, amorphous oxide films were deposited with targets having the composition of BixY3-xFe5O12 (x=0.0, 1.0, 1.5 and 2.0), and the films were annealed to form a garnet phase at 500-1000°C for 4h in air. The MS of the Bi containing films began rising at 600-650°C, and increased with annealing temperature. Then the MS decreased above 800°C and disappeared at about 900°C. The MS of the films with x=0.0 (YIG film) proceeded up at 700°C and showed a large value over 100 emu/cm3 at 1000°C. At the annealing temperatures over 800°C, non-magnetic crystalline phases were detected with the Bi containing films, and at 900°C the garnet diffraction peaks were disappeared.View full abstractDownload PDF (165K) -
Takashi Kamiya, Atsuyuki Nakano, Takeshi Nomura1992 Volume 39 Issue 11 Pages 999-1004
Published: November 15, 1992
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSEffect of Ag-winding on the magnetic characteristics of multilayer-ferrite chip-components (MLFCs) has been studied with special reference to the residual stress. MLFCs contain internal Ag-winding which may cause the residual stress on ferrite by the difference of the thermal exp-amsion behavior. The magnetic properties are thought to vary with the residual stress. Techniques used are finite element method and XRD. It is shown that the condition of Ag-winding has a remarkable effect on the magnetic characteristics. The higher the adhesion between Ag-winding and ferrite, the higher the residual stress.View full abstractDownload PDF (4822K) -
Seizo Takahashi, Takeo Nakagawa1992 Volume 39 Issue 11 Pages 1005-1010
Published: November 15, 1992
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDeep cup shaped compact were formed by a uniaxial press from soft ferrite granule inclurding small amount of resin binder PVA (Polyvinyl Alchohol) and liquid paraffin. This granule could be automatically filled into a cylindrical die cavity and pressed by a single stepped punch. 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 (1275K) -
Yasuharu Miyoshi, Naoyuki Okamoto, Keisuke Kageyama1992 Volume 39 Issue 11 Pages 1011-1014
Published: November 15, 1992
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSPowder metallurgical studies were made on Mn-Zn ferrites having fine grains. Fine powder is needed to get a dense ferrite with fine grains. We prepared experimentaly fine powder using a media agitation mill. The ferrites with grain size of sub-micron range had a linear relationship between initial permeability and mean grain size. Initial permeability of Mn-Zn ferrite with grain size as much as 0.7 μm was 330.View full abstractDownload PDF (2193K) -
Nobuyuki Hiratsuka, Hiromi Toda, Minoru Fujita, Hidehiko Kobayashi, Ta ...1992 Volume 39 Issue 11 Pages 1015-1018
Published: November 15, 1992
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSFerromagnetic composites which contained. iron and iron zinc ferrite(ZnxFe3-xO4) were prepared by the Thermite method, and their crystal phases and magnetic properties were investigated. The mixtures of Zn/α-Fe2O3 molar ratio of 0.3-2.0 were sintered between 400°C and 800°C for 1 hr in argon gas, and then were quenched.
The samples that were sintered between 450°C and 500°C had a large amount of a spinel phase(ZnxFe3-xO4). When the samples were sintered between 550°C and 700°C, the spinel phase was decreased by the thermal decomposition: non magnetic oxides, FeO and ZnO were formed. Iron powders were formed by the sintering at 800°C or above. The spinel phase was formed when Zn/α-Fe2O3 with molar ratio less than 1 was sintered at 500°C for 1hr in argon gas. The sample whose molar ratio of 0.35 had the magnetization of 85 emu/g and the coercive force of 0.11 kOe. The synthesized fine particles were sperical in shape and their diameters were in the range of 0.3 to 0.6μm. The future work is to make ferromagnetic materials which coexist irons and spinel ferrites without non magnetic oxides.View full abstractDownload PDF (1331K) -
Masaru Yokota, Masaaki Naka1992 Volume 39 Issue 11 Pages 1019-1022
Published: November 15, 1992
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSAmorphous titanium hydroxide with spherical shape was obtained from precipitation from homogeneous solution (PFHS) method using titanyl sulfate and urea as precipitant. Two stages of weight loss for the as-prepared particles were measured on heating process in air. First stage at lower temperature and second stage at higher temperature of weight loss correspond to the dissociation of hydrate and sulfate radical respectively. In particular, crystallization of as-prepared particles to anataze type titanium(IV) oxide proceed noticiably at about 600°C on heating. Existence of sulfate radical may play a role in stabilization of the amorphous state for titanium (IV) hydroxide.View full abstractDownload PDF (1795K) -
Mitsuo Ueki, Satoshi Kinoshita, Hisashi Suzuki1992 Volume 39 Issue 11 Pages 1025-1027
Published: November 15, 1992
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIt was suggested, in our previous results, that the superior creep resistance of nitrogen contained cermets was attributed to the skeleton formation of carbonitrides. Then, the creep resistance of TiC-Mo2C-Ni system alloy was studied as a function of the amount of addition TiO2 (or oxygen content of the alloy), because oxygen in the alloy would result in the inferior wettability of binder to hard phases. It was found that the resistance increased with increasing the amount of addition TiO2, being caused by the skeleton formation of carbides, as expected. It was concluded that the creep resistance of such cermets must naturally increase, as the wettability of nickel binder became inferior compared with the usual case.View full abstractDownload PDF (1457K) -
Toshiyuki Takahashi, Yuji Katsumura, Hirotaka Kiso, Hisashi Suzuki1992 Volume 39 Issue 11 Pages 1028-1032
Published: November 15, 1992
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe cutting performance under the high cutting speed (300-600m/min) by use of Al2O3-(10-50)mass%TiC ceramics tools was studied for gray cast iron (FC35) and carbon steel (S48C), comparing with that of Al2O3-15mass %ZrO2 ceramics tool. It was found that the flank wear of Al2O3-TiC ceramics tools in turning tests for FC35 increased with increasing titanium carbide content and decreased with increasing cutting speed; on the other hand, the wear in the tests for carbon steel increased with increasing titanium carbide content and with cutting speed. It was also found that the wear of Al2O3-ZrO2 ceramics tool was nearly the same as that of Al2O3-10%TiC ceramics tool. The above interesting phenomena were discussed.View full abstractDownload PDF (7137K) -
Hideyuki Masaki, Naoyoshi Watanabe, Shigetaka Wada1992 Volume 39 Issue 11 Pages 1033-1037
Published: November 15, 1992
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIn the process of milling α-Si3N4 raw powder with sintering additives using balls and mill made of β-Si3N4, the increment of the specific surface area of the powder and the wear of the balls and mill were measured.
The wear rate to the increment of the specific surface area depended on the filling ratio of balls, powder and liquid into the mill. Under the condtion that the volume of slurry was the same as that between balls, which is recognized as the effctive milling condition, the specific surface area increased from 6.1 to 22.4 m2/g after milling for 72h. The amount of Si3N4 contaminated from the balls and mill under the above milling condition, was accounted for 5.8 wt% of the raw powder.View full abstractDownload PDF (279K)
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