巻号一覧
52 巻, 3 号
March
選択された号の論文の13件中1～13を表示しています
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研究
研究
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多田 吉宏, 高谷 洋之2005 年 52 巻 3 号 p. 141-145
発行日: 2005年
公開日: 2006/04/28
ジャーナル オープンアクセスIn the powder metallurgical process to produce foamed cellular zinc, applicability of two organic foaming agents, usually used for resin, bistetorazole-piperazine (BTP) and bistetorazole-sodium (BTS), have been investigated in order to utilize their excellent porosity forming ability in manufacturing of metal foams. In the differential thermal analysis, both BTP and BTS showed sharp degradation characteristics with exothermic reaction at 608 K and 725 K, respectively. In Zn-BTP, in which the decomposition of BTP occurred rapidly at temperatures below the melting point of the zinc matrix, cracks often were observed in the surfaces of the samples. Therefore, it was not possible to keep the gas in the matrix, and the porosity did not reach 40%. On the other hand, successfully expanded foams with a porosity over 55% were obtained in Zn-BTS, in which the decomposition of BTS occurred at temperatures higher than the melting point of the matrix. The cellular structures consisted of small pores of about 300 μm or less in sizes, and the applicability of BTS to the manufacturing of zinc foams was verified.抄録全体を表示PDF形式でダウンロード (950K) -
松本 章宏, 小林 慶三, 西尾 敏幸, 尾崎 公洋2005 年 52 巻 3 号 p. 146-150
発行日: 2005年
公開日: 2006/04/28
ジャーナル オープンアクセスElemental powders of iron, aluminum and tungsten carbide powders has been used as starting materials for mechanical alloying and mixed to give the desired composition of Fe-40at%Al+50, 65vol%WC. The powder mixtures were milled for 360 ks using a planetary ball mill. Milled powders have been consolidated using pulse current sintering process at 1373 K in vacuum. The compacts thus obtained consisted of FeAl and WC. The FeAl-WC has had almost the same vickers hardness as the specimen prepared using milled Fe-40at%Al powder and WC powder in the previous study. However, the transverse rupture strength of FeAl-WC prepared in this study was inferior to the latter process. This is due to the different microstructure of FeAl-WC prepared by the different process.抄録全体を表示PDF形式でダウンロード (1609K)
特集 磁性材料
総報
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阿部 正紀2005 年 52 巻 3 号 p. 152
発行日: 2005年
公開日: 2006/04/28
ジャーナル オープンアクセスPDF形式でダウンロード (134K)
総説
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久保 馨2005 年 52 巻 3 号 p. 153-157
発行日: 2005年
公開日: 2006/04/28
ジャーナル オープンアクセスEnvironmental issues are greatly affected by the automobiles. One of the solutions is to introduce Green Cars into the market. Currently, Hybrid vehicles are green cars with good environmental performance and are expected to be popularized. HVs should have motor, inverter and batteries in addition to the conventional ICE vehicle units. Therefore, being compact, light-weighted and low cost are highly required.
Specific output of PM in current HVs has improved about 3.5 times more than a DC motor in early EV.
As of motor size, if 700 MGOe from MEXT‘s prospect will be implemented, it is possible to reduce the motor size by 30 to 40% with only material change.
It is quite safe to say that HVs' revolution with overwhelming fuel economy, environmental performance and quietness is achieved by materials improvement of units such as motor.抄録全体を表示PDF形式でダウンロード (1025K)
解説
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冨澤 浩之2005 年 52 巻 3 号 p. 158-163
発行日: 2005年
公開日: 2006/04/28
ジャーナル オープンアクセスRecently, the application of Nd-Fe-B sintered magnets on automobile is getting increased. These magnets are applied for driving motors/generators of Hybrid Electric Vehicle and Electric Power Steering motors. However a few improvements of these magnets are required for use of automobile. One point is the improvement on irreversible flux loss at high temperature. Therefore, it is necessary to improve the intrinsic coercivity for application on automobile. Intrinsic coercivity of Nd-Fe-B sintered magnets are depended on anisotropy field of the main phase and metallographical structure. While heavy Rare Earth substitution or some additions increase anisotropy field, other additions such as V or Mo improve factors related with their structure. As a result, the intrinsic coercivity increases. On the other hand, remanence decreases largely by use of these techniques. Therefore, it is important to improve the techniques of increasing remanence are developed simultaneously. In the future, electrical automobile will become major. So we must continue R&D for Nd-Fe-B sintered magnets to be the most important material in it.抄録全体を表示PDF形式でダウンロード (820K)
研究
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田島 伸, 服部 毅, 近藤 幹夫, 岸本 秀史, 杉山 昌揮, 亀甲 忠義2005 年 52 巻 3 号 p. 164-170
発行日: 2005年
公開日: 2006/04/28
ジャーナル オープンアクセスWe have developed new powder magnetic core, which was named HDMC (High Density Magnetic Composite), with high density, high magnetic flux density and high strength. However, the HDMC, which was fabricated from iron particles coated with phosphate glass insulator, has large eddy current loss under high frequency because the resistivity was small (<10 μΩm). To solve the deficiency, new type phosphate glass insulator was developed. The phosphate glass insulator with Sr2+ or Y3+ was found to have high resistivity above 50 μΩm in keeping the high magnetic flux density and strength of the HDMC. The HDMC, whose starting material was iron particles coated with strontium phosphate glass insulator, compacted at 1176 MPa with heat treatment at 673 K had properties as follows; d = 7.70 Mg/m3, μm = 610, B5k = 1.51T, B10k = 1.71T, bHc = 300 A/m, resistivity = 100 μΩm, TRS = 180 MPa, iron loss (Bmax = 1T, f = 400 Hz) = 400 kW/m3.抄録全体を表示PDF形式でダウンロード (1437K)
受賞記念講演
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森本 耕一郎2005 年 52 巻 3 号 p. 171-181
発行日: 2005年
公開日: 2006/04/28
ジャーナル オープンアクセスRecent progress in hydrogenation-decomposition-desorption-recombination (HDDR) process technologies is described with regard to the commercial production of Nd-Fe-B magnet powders. The applications of the powders to resin-bonded magnets and hot-pressed magnets are also presented. The HDDR reaction kinetics is an essential factor for improvements in magnetic properties of the Nd-Fe-B powders. Modified HDDR process, i.e., annealing the decomposed alloys under an Ar atmosphere, and then evacuating them with the correct desorption rate, can enhance magnetic anisotropy and coercivities of the powders simultaneously. Utilizing the rapidly solidified alloy flakes as a starting material of the HDDR process induces higher anisotropy in the final powders than using the conventional book-mold cast ingots. This can be ascribed to the complete elimination of α-Fe before the HDDR process. By these improved process, the following powders can be now commercially produced: high Br-type with (BH)max of 302-342 kJ/m3, high Hc-type with HcJ of 1430-1590 kA/m, and super high Br-type with (BH)max of 350-390 kJ/m3. Compression-molded resin-bonded magnets with (BH)max up to 199 kJ/m3 can be fabricated from the super high Br-type powders. Fully dense magnets produced by hot pressing the oriented high Hc-type powders exhibit excellent thermal stabilities.抄録全体を表示PDF形式でダウンロード (2657K) -
広沢 哲, 金清 裕和, 三次 敏夫2005 年 52 巻 3 号 p. 182-186
発行日: 2005年
公開日: 2006/04/28
ジャーナル オープンアクセスBasing upon studies of nanocrystallization and kinetic phase selection in Nd-Fe-B-based alloys in a composition range along the tie line between Fe3B and Nd2Fe14B with Nd concentration between approximately 6 and 9 atomic percent, a series of multicomponent Nd-Fe-B-Ti-C nanocomposite permanent magnets have been developed. The newly developed nanocomposite permanent magnets have high coercivity up to about 1 MA/m and remanence of 0.8 T when a high-throughput rapid solidification technique called “strip casting” is applied in the rapid solidification process. Together with the Fe3B/Nd2Fe14B-type, a series of the strip-castable nanocomposite permanent magnets now encompasses magnetic properties ranging from Br = 0.9 T, HcJ = 360 kA/m to Br = 0.8 T, HcJ = 1000 kA/m. Owing to the low concentration of rare earth elements in the material, powders obtained from these nanocomposite permanent magnets show excellent oxidation resistance, which makes these powders suitable for resin-bonded magnet applications. Particularly injection-molded magnets using thermoplastic resins of a high melting temperature and the high coercivity grade powders show excellent thermal stability.抄録全体を表示PDF形式でダウンロード (680K)
研究
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山元 洋, 形川 浩靖2005 年 52 巻 3 号 p. 187-193
発行日: 2005年
公開日: 2006/04/28
ジャーナル オープンアクセスExperiments were carried out to investigate the effect of composition, heat-treatment and nitrogenation conditions on the magnetic properties of Sm-Fe-Co-Cr-N compounds with TbCu7-type structure. The optimum preparation conditions of the compounds were as follows: composition: {Sm10(Fe0.9Co0.1)89.7Cr0.3}84.4N15.6, roller velocity: 50 m/s, heat treatment: 700°C for 60 min in high-purity Ar gas, and nitrogenation condition: 420°C for 10 h in high-purity N2 gas. Typical magnetic properties of the obtained compound powders were as follows: Jr = 0.99 T, HcJ = 756.5 kA/m, HcB = 541.8 kA/m, (BH)max = 141.8 kJ/m3 (17.8 MGOe), and Tc = 517°C. It was found that this sample was an exchange spring magnet from recoil loops of the hysteresis curve and X-ray diffraction patterns. The value of (BH)max for the compression-molding isotropic bonded magnet prepared by using {Sm10(Fe0.9Co0.1)89.7Cr0.3}84.4N15.6 powder was 102.6 kJ/m3 (12.9 MGOe), when the density of bonded magnet was 5.98 Mg/m3. And the average reversible temperature coefficient of Jr was α(Jr)ave. = -0.06%/°C, the temperature coefficient of HcJ in the range from 25°C to 125°C obtained by a linear extrapolation was α(HcJ) = -0.41%/°C.抄録全体を表示PDF形式でダウンロード (827K) -
津守 不二夫, 平田 正道, 島 進2005 年 52 巻 3 号 p. 194-198
発行日: 2005年
公開日: 2006/04/28
ジャーナル オープンアクセスA new computational system is proposed and developed to simulate magnetic powder behavior under applied magnetic field. It is well-known fact that magnetic powder builds up a chain or column structure in an applied magnetic field, but it is difficult to simulate accurately by conventional modeling. In the present paper, a Distinct Element Method (DEM) is developed and coupled with a magnetic FEM. Magnetic flux in the assembly of particles can be calculated by the FEM, thereby the force exerted to each particle can be obtained. The force is then use to simulate the movement of the particles by the DEM. A simple analysis of two magnetic particles in applied magnetic field shows a difference from that by the conventional simulation system. Further, the present simulation shows that the structures consist of not only simple chains of one particle wide but also columnar structure of two or more particles wide.抄録全体を表示PDF形式でダウンロード (1722K)
受賞記念講演
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村瀬 琢, 青木 卓也, 梅田 秀信2005 年 52 巻 3 号 p. 199-206
発行日: 2005年
公開日: 2006/04/28
ジャーナル オープンアクセスOur purposes are to produce a fine and uniform microstructure and to achieve high quality products from the MgZn ferrites including some impurities. The discontinuous grain growth contributed with the impurities is prevented by sintering under low oxygen partial pressure or Fe2O3-deficient MgZn ferrites. On those conditions, the second phase, (Mg,Zn,Fe)O, is formed and strongly affects core loss in MgZn ferrites. Substitution of CuO enables MgZn ferrites to be sintered at low temperatures, and it leads to the reduction of the core loss because of the formation of fine microstructure. The calcium sulfate is formed from impurities contained in the raw materials for MgZn ferrites during calcinations. When ferrite powders are not treated by water, the calcium sulfate remains within grains and the core loss increase. The relaxation phenomena of MgCuZn ferrites are interesting. From the analysis of frequency dispersion, the natural resonance frequency does not agree with the one calculated from Snoek's limit and the initial permeability measured in the MgCuZn ferrites.抄録全体を表示PDF形式でダウンロード (2133K)
研究
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高川 建弥, 福地 英一郎, 村瀬 琢2005 年 52 巻 3 号 p. 207-211
発行日: 2005年
公開日: 2006/04/28
ジャーナル オープンアクセスMagnetic properties of manganese zinc ferrites with high saturation magnetic flux density (Bs) were investigated. Bs of more than 500 mT at 100°C was obtained with the composition where Fe2O3 is approximately 64 mol% or more. In Fe-rich compositions, an increased number of cation vacancies were generally observed. This causes changes in magnetic properties as time elapses. The cation vacancies also causes the deterioration of core loss (Pcv) and initial magnetic permeability. By sintering under low oxygen partial pressure (Po2), the number of cation vacancies decreased, however, Pcv increased. One cause of this is the decrease of electrical resistivity. The total electrical resistivity is dominated by that at grain boundary. We also studied the cooling rate, which controls the resistivity at grain boundary.抄録全体を表示PDF形式でダウンロード (756K) -
鈴木 裕宣, 酒井 武明2005 年 52 巻 3 号 p. 212-216
発行日: 2005年
公開日: 2006/04/28
ジャーナル オープンアクセスNewly Fe-1.5mass%Sn-0.14mass%P-1.5mass%Mo sintered alloy has been developed for soft magnetic parts. Brittleness of Fe-1.5mass%Sn-0.14mass%P sintered alloy was improved by the addition of molybdenum more than 1.0 mass%. The alloy was produced by highly productive 1P1S process, which means one time pressing and one time sintering, in condition of compacting pressure 600 MPa and sintering temperature 1473 K. The alloy shows magnetic induction (B1k) of 1.5 T at magnetic field 1 kA/m, coercive force (Hc) of 67 A/m, maximum permeability (μm) of 5.7 mH/m. These values are superior to those of a pure iron produced by costly 2P2S process composed of re-pressing and re-sintering in addition to compacting and sintering. The Fe-Sn-P-Mo sintered alloy has been applied for the magnetic yoke of a voice coil motor because of its good magnetic properties and high productivity.抄録全体を表示PDF形式でダウンロード (1092K)
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