All issues
Volume 46, Issue 6
Displaying 1-18 of 18 articles from this issue
- |<
- <
- 1
- >
- >|
-
Kei Tokumoto, Tetsunori Kitada, Hironobu Shinoaki, Shigeya Sakaguchi1999 Volume 46 Issue 6 Pages 573-578
Published: June 15, 1999
Released on J-STAGE: July 12, 2010
JOURNAL OPEN ACCESSTi-Mo-47.4vol%TiC alloys were prepared through P/M technology and their microstructures and mechanical properties were investigated as a function of the mixed amounts of Mo. Ti-(2.6vol%-16.4vol%)Mo-TiC alloys had higher relative density values than 97%. Ti-TiC alloy has TiC phase, α-Ti phase and β-Ti phase, while Ti-(2.6vol%-27.0vol%)Mo-TiC alloys have TiC phase and β-Ti phase. The contents of TiC phase in alloy were increased compared with the amounts of mixed TiC, while they were decreased with the increase of the mixed amounts of Mo. Mean diameter of TiC grains in the alloy is increased with the increase of sintering temperature, while it is decreased remarkably with the increase of mixed amounts of Mo. Hardness and transverse-rupture strength of these alloys were slightly affected by mixed amounts of Mo. Corrosion resistance of Ti-(2.6vol%-8.5vol%)Mo-TiC alloys were thought to be excellent. It was concluded that Ti-(2.6vol%-8.5vol%)Mo-47.4vol%TiC alloys have better combination of hardness, transverse-rupture strength and corrosion resistance than those of the other alloys.View full abstractDownload PDF (3379K) -
[in Japanese]1999 Volume 46 Issue 6 Pages 580
Published: June 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (99K) -
Akira Fukuno, Tomomi Yamamoto, Tetsuya Hidaka1999 Volume 46 Issue 6 Pages 581-588
Published: June 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSNano composite magnet material consisting of hard magnetic SmFe7Nx phase and soft magnetic α Fe phase were developed through a process of rapidly quenching method including heat treatment and nitrogenation. Well balanced magnetic performance were obtained for the alloys with the composition of (Sm8Zr3Fe85Co4)N15. The ranges of grain sizes are 20-40nm which are enough small to create exchange coupling interaction between soft and hard magnetic grains. The ratio of α Fe phases with higher magnetization are measured approximately 20% by TEM observation. TEM-EDX study revealed that SmFe7Nx phase have a composition of richer Sm ratio than that of 1-7stoichiometry. Magnetic properties of those powders are as follows: Br=0.97T, HcJ=752kJ/m, (BH)max=140kJ/m3. Bonded magnets have been fabricated with thermoelastic and thermoplastic resins.View full abstractDownload PDF (4584K) -
Hiroshi Yamamoto, Takeshi Okano1999 Volume 46 Issue 6 Pages 589-593
Published: June 15, 1999
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThis experiment was carried out to. investigate the magnetic properties of Sm-Fe-Co-V-Cu-Nb system nitriding compounds with SmFe7 type structure. The Sm10(Fe0.95Co0.05)81V5.0Cu1.0Nb3.0 alloy ribbons were prepared by the single roller liquid rapid-quenching method. And the effect of roller velocity, heat-treatment and nitrogenation on some properties were investigated. The optimum preparation condition and some properties are as forrows: roller velocity -50m/s; pre-heating condition -700°C×70min in high-purity Ar atmosphere; nitriding condition -500°C×5h in high-purity N2 gas at pressures of 4.9 MPa; magnetic properties -HcJ=554.6 kA/m (6970 Oe), σr=91.11×10-6 Wb⋅m/kg (72.54 emu/g), σs, =128.2×10-6 Wb⋅m/kg (102.1 emu/g), Tc=457.4°C; lattice constant -a=0.5007 nm, c=0.4316 nm, c/a=0.8620.View full abstractDownload PDF (1679K) -
Yoshiyuki Hashimasa, Masakazu Okita, Shuji Mino, Naoyuki Ishigaki1999 Volume 46 Issue 6 Pages 594-598
Published: June 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSAligning behavior of magnetically anisotropic Nd-Fe-B powder under compaction in magnetic field was studied in order to produce high energy bonded magnets composed of this powder and an epoxy resin binder. It was previously reported that applying a strong magnetic field to the powder before the compaction operation is very effective to make highly oriented bonded magnets. In this study, influence of applying a static magnetic field after charging the pulsed field was investigated with regard to the powder alignment. It was found that the degree of powder orientation is strongly dependent on the duration of the static magnetic field in the compaction process. The static field is thought to maintain the powder arrangement formed by the initial pulsed field.View full abstractDownload PDF (461K) -
Soichi Yamazaki, Toshiaki Yamagami, Kiyoshi Shiobara, Koji Akioka1999 Volume 46 Issue 6 Pages 599-603
Published: June 15, 1999
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSRare earth bonded magnets with versatility on shaping and high density, composed of isotropic Nd-Fe-B powder and thermoplastic resin (Nylon-12, PBT and PPS), were developed with warm compression molding.
(1) Compounds with magnet powder volume fraction of 80vol.%, composed PBT or Nylon-12, have versatility on shaping and compressibility at relatively low pressure. Coin-shaped magnets with a thickness of 0.3mm and ring magnets with a wall-thickness of 0.4mm were moldable with these compounds at the pressure of 250MPa. The properties of these bonded magnets were as follows: pore=0vol.% in substance, density =6.2Mg/m3 and (BH)max=97.9kJ/m3 (12.3MGOe).
(2) Compounds with magnet powder volume fraction of 90vol.% have higher compressibility than the compounds for compaction molding at high pressure. This is because that viscosity of resin during the molding is easy to optimize and spring-back after molding is small in warm compression molding. The properties of the magnet were as follows: density=6.7Mg/m3 and (BH)max=115kJ/m3 (14.4MGOe) at pressure of 1250MPa.
In this way, warm compression molding is applicable to extensive compounds through adjusting the molding condition.View full abstractDownload PDF (1913K) -
Yoshikazu Suzuki, Masanobu Awano, Naoki Kondo, Tatsuki Ohji1999 Volume 46 Issue 6 Pages 604-609
Published: June 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe present work focused on developping textile microstructure and improving magnetic properties of the 3Y-ZrO2/Ba-hexaferrite composite by post-plastic deformation. In summary,
A 3Y-ZrO2/Ba-hexaferrite composite has been fabricated by powder metallurgical processes. Because BaFe12O19 particles behave like "small magnets", agglomerated particles (5 to 10μm) were observed in the composite. However, they homogeneously dispersed in the TZP matrix from a macroscopic viewpoint.
The deformation mechanism of the composite at 1200-1300° was very likely associated with the dislocation motion of the relatively large hexaferrite particles. The composite had sufficient deformability at low flow stress.
Post-plastic deformation on the composite improved both saturation magnetization and coercivity, probably due to the alignment of the hexaferrite platelet particles. In order to obtain good magnetic properties for magnetic-particlesdispersed composites, the post-plastic deformation can be a new complemental technique to the conventional slurry pressing under the magnetic field.View full abstractDownload PDF (6504K) -
Ryo Ikeda, Koichi Kakizaki, Nobuyuki Hiratsuka1999 Volume 46 Issue 6 Pages 610-614
Published: June 15, 1999
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSZ-type hexagonal ferrites for ultra high frequency of gigahertz range were prepared by substitution of trivalent iron ions for various metal ions. Thereby improving a sintering process and the addition of lwt.% BaCO3 to calcined powder, single-phase Z-type ferrite was obtained even when we used the conventional ceramic techniques. Initial permeability of Z-type ferrites with composition of Ba3Co2Cux/2Six/2Fe24-xO41 (X=0) was 17.8 which was sufficiently larger than the value previously reported. Moreover, the limit of frequency was 0.635GHz which was as large as previously reported value. In spite of low bulk density (4.28g/cm3), initial permeability of Z-type ferrites with composition of Ba3Co2Cux/2Six/2Fe24-xO41 (X=1) was 9.51 and the limit of frequency was 1.5GHz which were useful and practical values as magnetic materials for ultra high frequency. When the amount of substitutional metal ions increased, initial permeability and resonance frequency were decreased. In substitution by Cu2+ ion and Nbs5+ ion, initial permeability of Z-type ferrite with composition of Ba3Co2Cu2X/3NbX/3Fe24-XO41 (X=1) was 8.1 and the limit of frequency was 1.2GHz which was less than the values of Ba3Co2CuX/2SiX/2Fe24-XO41 (X=0, 1). Quantitative and qualitative analysis indicated that various substitutions have led to the formation of two hexagonal structures.View full abstractDownload PDF (3326K) -
Koichi Kakizaki, Nobuyuki Hiratsuka1999 Volume 46 Issue 6 Pages 615-620
Published: June 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe effect of additives on low temperature preparation for barium ferrite thin films and their magnetic properties have been investigated. Bi2O3 and PbO which have low melting point were selected for additives. Barium ferrite thin films were deposited on fused quartz substrate by r.f. diode magnetron sputtering method. In order to control the composition in the deposited barium ferrite films, several sintered BaFe2O4 chips, Bi2O3 chips and PbO chips were placed on the barium ferrite target with Fe/Ba ratio of 10. The film thickness was about 2000Å. As-deposited films were post-annealed at the temperatures between 500°C and 700°C for 5 hours in air.
Both Bi added barium ferrite films with Bi/Ba ratio between 2.0 and 2.3 and Pb added barium ferrite films with Pb/ Ba ratio of 3.2 or above were well crystallized by the post-annealing at 550°C for 5 hours in air. Especially, Pb added barium ferrite films with Pb/Ba ratio of 0.55 showed excellent magnetic properties, and its grains were small and uniform.View full abstractDownload PDF (3794K) -
Makoto Terasawa, Koichi Kakizaki, Nobuyuki Hiratsuka, Oh-Heung Kwon1999 Volume 46 Issue 6 Pages 621-625
Published: June 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSCrystal oriented manganese zinc ferrites were made from acicular α-FeOOH, Mn(C5H7O2)3 and Zn(C5H7O2)2 as raw materials. The materials were mixed and calcined at 800°C for 4 hours in nitrogen atmosphere. The calcined acicular manganese zinc ferrite fine particles were formed into a thin troidal cores, consist of multi-layered. The green bodies were sintered at the range of 1100 to 1250°C for 4 to 8 hours in air, thereafter cooled in nitrogen atmosphere.
The crystals of sintered manganese zinc ferrites were strongly oriented to the direction of {111} plane of the spinel, which was all formed along the upper plane of troidal cores. The behavior of crystal growth was similar to that of manganese zinc ferrite single crystal. The initial permeability of crystal oriented manganese zinc ferrites was 1380 at 0.1MHz and it was not allowed to decay up to 2.2 MHz at the operating condition of the 3dB decrease of the initial permeability. The high crystal orientation and suitable grain size has greatly contributed to the improvement of magnetic properties.View full abstractDownload PDF (3450K) -
Tadayoshi Nishihama, Koichi Kakizaki, Nobuyuki Hiratsuka, Oh-Heung Kwo ...1999 Volume 46 Issue 6 Pages 626-630
Published: June 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIn general, the core loss of manganese zinc ferrites is affected by their grain sizes, resistivity and that spinet phase is ideally perfect or not. The homogeneity of microstructure is particularly influenced by starting raw manganese oxides. Therefore, manganese zinc ferrite samples were made from MnO2, Mn2O3 and Mn3O4, respectively, to and investigate their magnetic properties and homogeneity of spinel structure.
The sample made of Mn3O4 indicated an excellent frequency dependency for initial permeability and core loss. Moreover the homogeneity of cation configuration in the spinel structure was confirmed by X-ray diffraction analysis. The result of homogercity of rile spinet structural coincided with the arlalytical results of temperature dependence of magnetization.
Furthermore, the influence of manganese oxide as starting material, on homogeneity of spinel structure was examined by using thermogravimetry - differential thermal analysis.
It may be concluded that the reaction between Mn3O4 and Fe-Zn oxide mixture proceeds at first in all combination of manganese oxide and oxide mixture, and then Mn-Zn-Fe spinel was formed.View full abstractDownload PDF (367K) -
Takuya Aoki, Naoyoshi Sato, Takeshi Nomura1999 Volume 46 Issue 6 Pages 631-635
Published: June 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSFerric oxide which is a principal raw material for ferrite production usually contains small amount of anion as impurities. Because ferric oxide has been generally produced from iron chloride or iron sulfate solutions obtained from pickled liquor, in this paper, we have investigated the effect of chloride ions on the formation of Mg, Zn, Cu and Mn ferrites. Mg ferrite and Zn ferrite are shown that the spinel phase is formed at lower temperature in the case of iron oxide containing a small amount of chloride ions compared with that case of sulfate ions. On the other hand, Cu ferrite and Mn ferrite are shown that the spinel phase is formed at same temperature in the case of iron oxide containing chloride ions. The reason of the low temperature formation of Mg and Zn ferrites may be due to the formation of an active magnesium chloride of some kind of zinc chloric acid in the course of calcination.View full abstractDownload PDF (332K) -
Isao Kanada, Takuya Aoki, Taku Murase, Takeshi Nomura1999 Volume 46 Issue 6 Pages 636-642
Published: June 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe effects of substitution of Mn2O3 for Fe2O3 Or CuO for MgO in MgZn ferrite have been studied in order to achieve low core loss, focusing on the microstructure, the initial permeability and the resistivity of MnZn, MnMgZn, and MnMgCuZn ferrites.
Initial permeability and resistivity of both MnMgZn and MnMgCuZn ferrites are higher than those of MgZn ferrite. Intragrain pores were observed in all of these ferrites. The pore density increases with grain growth.
The core loss of these ferrites consists of hysteresis loss and eddy current loss at frequencies lower than 120kHz. Hysteresis loss clearly depends on initial permeability because of magnetic anisotropy, grain size and pore density. It has been found that eddy current loss is related to the microstructure and not to the resistivity. It is suggested that the decrease in the amount of pores inside the grains is effective to lower hysteresis and eddy current losses.
Substitution of Cu enables MgZn ferrite to be sintered at lower temperatures, and it leads to the reduction of the core loss because of the formation of fine microstructure having small grain and low pore density. The lowest core loss (320kW/m3 at 100°C, 100mT and 100kHz) was achieved in the case of 11mol% CuO material sintered at 1120°C.View full abstractDownload PDF (4636K) -
Tatsuo Fujii, Kenji Ayama, Makoto Nakanishi, Jun Takada1999 Volume 46 Issue 6 Pages 643-647
Published: June 15, 1999
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSFeTiO3-a-F2O3 solid solution films were epitaxially formed on an a-Al2O3 (001) single crystalline substrate by activated reactive evaporation method. The films prepared at low substrate temperature of 500°C had the corundum structure where Fe and Ti ions occupied the cation sites randomly. While the Fe2-xTixO3 films with x≥0.4 prepared at 700°C had the ilmenite structure where Fe and Ti ions were arranged in order. Only the films with the ordered Fe and Ti ions had large ferrimagnetic moments, though the observed spontaneous magnetization was less than a half of the ideal value expected from the fully ordered ions. Moreover the resistivity of the solid solution films dropped to 10-1Ωcm due to the formation of the mixed valence states between Fe2+ and Fe3+. We revealed this system was one of the candidates for new oxide magnetic semiconductor films.View full abstractDownload PDF (372K) -
Akira Sugiyama, Keizo Kobayashi, Kimihiro Ozaki, Akihiro Matsumoto, To ...1999 Volume 46 Issue 6 Pages 648-652
Published: June 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe formation process of Th-Dy-Fe giant magnetostrictive alloy made by the mechanical alloying (MA) and the spark plasma sintering (SPS) was investigated. The MA was performed in a planetary ball mill using three elemental powders. The powders were prepared by the mixing of (TbxDy1-x)Fey (x=0-1.0, y=1.6, 1.8, 2.0). The MA powders were consolidated by SPS method. From the result of X-ray analysis, the structure of the MA powder was close to amorphous after milling for 360ks. During SPS, the structure of sample heated below 773K was not change from that of room temperature. On the other hand, the structure of sample heated above 773K was change to intermetallic compounds such as TbFe2, DyFe2 and Dy6Fe23. From the result of X-ray analysis, the amount of Dy6Fe23 phase, which is not useful for magnetostrictive effect, was smallest after SPS by using the composition of (Tb0.5Dy0.5)Fe1.8 powders. The relative density of sample after SPS at 1073K was about 98%. It was found that the composition of (Tb0.5Dy0.5)Fe1.8 and sintering temperature of 1073K were the best condition for making magnetostrictive alloy by using MA and SPS.View full abstractDownload PDF (2304K) -
Masami Ueda, Osamu Yamashita, Yoshihisa Kishimoto, Ken Makita1999 Volume 46 Issue 6 Pages 653-658
Published: June 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe iron-silicon-aluminum alloys (especially Sendust) have been widely used for the application requiring high saturation flux density, low coercive force and high electric resistivity. For this reason they have been appreciated for magnetic thin film heads. However, they are too hard and brittle to be made into thin film by rolling or to prepare three dimensional complex-shaped products by mechanical work or conventional powder metallurgy process. The reduction in the size and weight of apparatus that can be accomplished by its use should have an important effect on technical developments. Previous study showed that the powder metallurgy process with spray drying method using gas atomized Sendust powders was an excellent process for producing near-net-shape parts with high performance and high precision in dimension after sintering. The high price of gas atomized powders, however, makes us consider to use low price powders. In this report the combined powders of carbonyl iron powder, iron-silicon powder crushed and iron-aluminum powder crushed can promise to reduce the cost and maintain the high performance.View full abstractDownload PDF (4339K) -
Katsushi Kusaka, Daisuke Kimura1999 Volume 46 Issue 6 Pages 659-665
Published: June 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe objective of this study is firstly to elucidate the effect of geometrical defect (artificial semi/full slit) on magnetic properties and secondly to evaluate the magnetic restoration by ferromagnetic paste filling to slit for the 4-types of soft magnetic materials. In this case, ferromagnetic pastes consist of the mixture of water-atomized powder of almost the same type (as specimen) and binding agent.
The results obtained were summarized as follows:
(1) DC magnetic properties are more or less degraded by semi/full slit, where magnetic induction (B) are less degraded in comparison with maximum permeability (μm), especially for high-μ permalloy.
(2) AC magnetic properties, especially, specific permeability (μa) are degraded nearly in the same way as DC ones in low frequency range and less degraded at higher frequency (degradation ratio Δμa/μa<0.1, 100kHz).
(3) As for DC magnetic properties, magnetic induction (B) tends to be more restored than maximum permeability (μm) by ferromagnetic paste filling to slit, although fairly plot-scattered.
(4) AC magnetic properties at 60Hz also are enhanced upto restoration ratio Δμa'/Δμa-1/2 roughly by ferromagnetic paste filling to full slit, almost irrespectively of material type and slit width.
(5) This ferromagnetic paste method is more effective in DC or low frequency range due to the result that Δμa/μa is fixed small for semi slit and linearly decreases for full slit with rise of applied frequency.View full abstractDownload PDF (2992K) -
Katsushi Kusaka, Tohru Takesita, Tetsuya Kondo1999 Volume 46 Issue 6 Pages 666-672
Published: June 15, 1999
Released on J-STAGE: July 12, 2010
JOURNAL OPEN ACCESSThe objective of this study is mainly to elucidate the effect of stress/strain on DC/AC magnetic properties for the 4-types of soft-magnetic materials with residual pores and without. Experimentally, DC/AC magnetic measurement of PM and C/W (Cast & Wrought) ring-shape specimens were carried out in radially loaded, unloaded and annealed states in consideration of elastic and plastic strain.
The result obtained were summarized as follows:
(1) DC magnetic properties, especially maximum permeability (μm) is more sensitive to stress/strain, where degradation ratio Δμm/μm is roughly 0.4 and 0.7-0.8 (strain ε=0.005) for pure iron and magnetic alloys, respectively.
(2) In this case, PM (porous) specimens tend to be more magnetically degraded than C/W (solid) ones, presumably due to localized microstrain arised by stress concentration effect around residual pores.
(3) As for AC magnetic properties, specific permeability (μa) is degraded in almost the same way as maximum permeability (μm) and also, core loss (Pcv) is apparently reduced by stress/strain, although depending on frequency (60Hz-100kHz).
(4) DC/AC magnetic properties (μm, μa) are partially restored in the range 0.1-0.2 of degradation ratio by stress relief (unloading) at higher strain (ε=0.02), including C/W specimens.
(5) Through strain relief annealing, DC/AC magnetic properties are restored to the original value at 873K for pure iron but are not always restored to the original ones even at 1073K for magnetic alloys.View full abstractDownload PDF (548K)
- |<
- <
- 1
- >
- >|