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Volume 54, Issue 6
June
Displaying 1-9 of 9 articles from this issue
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Paper
Paper
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Tadahiro Wada, Takaomi Toihara2007 Volume 54 Issue 6 Pages 405-409
Published: 2007
Released on J-STAGE: January 29, 2008
JOURNAL OPEN ACCESSIn this study, the tool wear was experimentally investigated in order to clarify the effective tool material for the turning of SCr420H. SCr420H was turned with three kinds of physical vapor deposition (PVD) coated cemented carbide tools. The coating films used were TiN, (Ti, Al)N, (Ti, W)N and (Ti, W, Si)N coating film. (Ti, W, Si)N is a new type of coating film. The main results obtained are as follows: (1) The (Ti, W, Si)N coating film has both high hardness and high critical scratch load. (2) In the turning of SCr420H, the wear progress of the (Ti, W, Si)N coated cemented carbide tool is slowest.View full abstractDownload PDF (657K)
Special Issue:The Fundamentals and Applications of Ferrites and Magnetic Composites
Summarization
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Yohtaro Yamazaki2007 Volume 54 Issue 6 Pages 412
Published: 2007
Released on J-STAGE: January 29, 2008
JOURNAL OPEN ACCESSDownload PDF (122K)
Paper
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Hiroshi Yamamoto, Hiroki Nishizaki2007 Volume 54 Issue 6 Pages 413-420
Published: 2007
Released on J-STAGE: January 29, 2008
JOURNAL OPEN ACCESSSingle phase Sr-Ca-Nd M-type ferrite fine particles were prepared by controlling the chemical coprecipitation method and subsequent heat treatment. The chemical reagents used for this experiment were SrCl2·6H2O, FeCl3·6H2O, CaCl2·2H2O and NdCl3·6H2O. The chemical coprecipitation composition were chosen according to the formula {(SrO)1-x(CaO)x·n/2(Fe2O3)}100-y(Nd2O3)y, where n was fixed at 7.0, x was varied between 0.1 and 0.5, y between 0.0 and 8.0. A water solution containing Sr2+, Fe3+, Ca2+ and Nd3+ was poured into a solution of NaOH (pH=13.0). The precipitated products were boiled at 100°C for 2h, and they were carefully washed with pure water for 24h. The washing was repeated 5 times and the products were then filtered and dried at 80°C for 12h. The obtained fine particles were heated at a temperature between 850 and 1000°C for 2h in air to get single phase Sr-Ca-Nd M-type ferrite fine particles. The most prominent magnetic properties have been observed for the sample with the preparation composition of {(SrO)0.7(CaO)0.3·3.5(Fe2O3)}97(Nd2O3)3; they are as follows: σs=84.1×10−6 Wb·m/kg (66.9 emu/g), σr=42.5×10−6 Wb·m/kg (33.8 emu/g), HcJ=505.3 kA/m (6.35 kOe), α(σr)=−0.18%/°C, α(HcJ)=0.11%/°C and Tc=453°C.View full abstractDownload PDF (861K) -
Hiroshi Yamamoto, Yoshihito Sawayama2007 Volume 54 Issue 6 Pages 421-427
Published: 2007
Released on J-STAGE: January 29, 2008
JOURNAL OPEN ACCESSAn experiment was carried out to investigate the effect of Co-Stearate as a reducing agent on the magnetic and physical properties of anisotropic BaFe2-W type ferrite magnets. It was found that the magnetic properties of BaO·8.5Fe2O3 were improved by adding 0.3 wt% of Co-Stearate, 0.5 wt% of SiO2, and 0.5 wt% of CaO together. The optimum conditions for making magnets were as follows: Chemical composition Ba0.975Ca0.129Si0.144Co0.010C0.075Fe2+2.627Fe3+15.215O27, semisintering condition 1350°C × 4.0 h in nitrogen gas atmosphere, drying condition 180°C × 2.0 h in air, sintering condition 1180°C × 1.5 h in nitrogen gas atmosphere. The magnetic and physical properties of a typical sample were Jm=0.48 T, Jr=0.44 T, HcJ=199.7 kA/m, HcB=196.2 kA/m, (BH)max=34.4 kJ/m3, Tc=497°C. The lattice constants of this compound were a=5.893 × 10−10m, c=32.86 × 10−10m, and c/a=5.577.View full abstractDownload PDF (681K) -
Yukinori Yamada, Shingo Ohashi, Takeshi Ariyoshi, Takanori Sawai, Shig ...2007 Volume 54 Issue 6 Pages 428-431
Published: 2007
Released on J-STAGE: January 29, 2008
JOURNAL OPEN ACCESSWe have investigated a motor with a stator made of SMC, soft magnetic composite material. The features of SMC are improvements in eddy current loss at the flux density changing, as SMC is made by a compaction of iron powder covered with insulated layer. Especially, downsizing of a motor core and simplification of production process of stator is expected by using the material.
The material has a disadvantage in efficiency of motor driving as the iron loss is worse than that of conventional laminated core, but we found that the driving efficiency will be close to the laminated core. We expect also the improvement of further efficiency with the optimization of a 3-dimensional magnetic circuit.View full abstractDownload PDF (663K) -
Satoshi Sunada, Masakazu Ii, Koichiro Morimoto, Kazuhiko Majima2007 Volume 54 Issue 6 Pages 432-438
Published: 2007
Released on J-STAGE: January 29, 2008
JOURNAL OPEN ACCESSSoft magnetic composites (SMC) have attracted a growing interest since they have the positive points in isotropic magnetic properties and high electric resistivity. They also have the advantage in fabricating complex shape products easily. In this experiment, water atomized iron powder with phosphate insulator coating around its surface was mixed with binder and three kinds of SMC specimens were prepared. The first one is prepared without binder (Sample A), the second one is prepared by using silicon resin as binder (Sample C), and the third one by using thermosetting polyimide (Sample D). In addition, the water atomized iron powder with MgO insulator coating (Sample B) was used, where the silicon resin and Bi-B system glass with low-temperature melting point were used as binder. Using these four kinds of samples, their corrosion behavior were investigated by electrochemical method. In the active zone, Sample D indicated the highest corrosion resistance due to the prevention of anodic reaction. It is because the added thermosetting polyimide prevents the penetration of corrosion solution into the sample. On the other hand, in the passive zone, Sample B showed the highest corrosion resistance due to the formation of uniform passive state film with good quality. It is because the added Bi-B system glass prevents both grain separation and exposure of newly-formed surface to corrosion solution.View full abstractDownload PDF (1372K) -
Akira Fujii, Yoshihisa Mori, Kenji Kawano, Shinya Kusumi, Hiroshi Kish ...2007 Volume 54 Issue 6 Pages 439-443
Published: 2007
Released on J-STAGE: January 29, 2008
JOURNAL OPEN ACCESSThe lattice constant of the NiZnCu ferrite was evaluated by X-ray diffraction using the synchrotron radiation source. In the experiment of the powder X-ray diffraction under pressure, the lattice constant shows the different values between the increment process and the decrement process. The behavior is similar to the change of the inductance under pressure. On the other hand, in the experiment of the mapping on the simplified multilayer chip inductor, the lattice constant depends on the sintering temperature and the location in the device. Moreover, Ag particles diffused from the Ag-conductor are found on the sample sintered at 920°C by Electron Probe Micro-Analysis. These results suggest that the lattice distortion of the NiZnCu ferrite caused by the stress from Ag-conductor and Ag-diffusion affects the magnetic permeability.View full abstractDownload PDF (972K) -
Kunio Okimoto2007 Volume 54 Issue 6 Pages 444-450
Published: 2007
Released on J-STAGE: January 29, 2008
JOURNAL OPEN ACCESSThe anisotropies of mechanical strength and sound velocities in sintered Sr-ferrite compacted under a magnetic field were investigated by a bending test and an ultrasonic pulse method, respectively. The aim of this study was to clarify the effect of the orientation forming on the mechanical strength and the elastic modulus of the compact. The direction of the applied magnetic field was parallel to that of the compacting pressure. The magnetic field strength was 675 kA·m−1, while the green compact was 32 mm long, 7 mm wide and approximately 7 mm high. Compacting pressures of 50 MPa and 100 MPa were used and three different sintering temperatures were employed, namely 1200°C, 1225°C and 1250°C. The two directions of the applied sound waves were parallel to the direction of the magnetic field and the compacting pressure (Face A), and perpendicular to these directions (Face B). The directions of the applied bending load were same conditions to the sound waves.
The flexural strength of the orientated sintered compact was smaller than that of non-orientated one. The anisotropy of the longitudinal sound velocities was greatest in the orientated sintered compact; the maximum difference between the two velocities was about 8% for such samples. In addition, some anisotropy in the longitudinal sound velocities in the non-orientated sintered compact was detected. This is due to the fact that mechanical alignment of the magnetic particles occurred during the compacting process.View full abstractDownload PDF (713K) -
Takashi Ikenoya, Kenji Kamishima, Koichi Kakizaki, Nobuyuki Hiratsuka2007 Volume 54 Issue 6 Pages 451-454
Published: 2007
Released on J-STAGE: January 29, 2008
JOURNAL OPEN ACCESSSiO2-coated Fe3O4 samples were prepared by the sol-gel processing with several reaction time conditions. The samples were sintered in vacuum at 1000°C for 2 hours. MR ratio became the maximum of 3.6% for 12.9 vol.% SiO2 sample. This value is large compared with that of Fe3O4 reported before. The magnetization and magnetoresistance are saturated at the same magnetic field of about 4 kOe, which suggests that the MR effect is caused by magnetic scattering.View full abstractDownload PDF (571K)
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