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Volume 42, Issue 1
Displaying 1-22 of 22 articles from this issue
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[in Japanese]1995 Volume 42 Issue 1 Pages 2
Published: January 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (80K) -
Ryoji Nakayama, Takuo Takeshita1995 Volume 42 Issue 1 Pages 3-10
Published: January 15, 1995
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSMagnetic properties and microstructures of Nd-Fe-B magnet powders produced by two different hydrogen treatments were studied. One of the hydrogen treatment is a selective hydrogen decrepitation (HD) process and the other is the hydrogenation decomposition desorption recombination (HDDR) process, which is a new production process for high-performance Nd-Fe-B magnet powder. The anisotropic magnet powders produced by the selective HD process possess high coercivities, but coercivities of green compacts of the powders are very low. High-coercivity Nd-Fe-B magnet powders were produced by the HDDR process. The substitution of Fe with Co and the addition of elements such as Ga, Zr, Nb, Hf and Ta was found to be very effective for enhancing magnetic anisotropy of HDDR magnet powders. Typical magnetic properties of anisotropic bonded magnet made from HDDR magnet powders are Br=9.4 kG, iHc = 13.3 kOe and BHmax = 20.1 MGOe. Magnetic properties of anisotropic HDDR magnet powders depend on the powder particle size, and the particle size for the highest magnetic properties is 45-212 μm. It was found that the powder particles of anisotropic HDDR magnet powder consist of fine Nd2(Fe, Co)14 B crystals of the size of about 0.3 μm, and boundary-layer phase is essentially absent.View full abstractDownload PDF (3449K) -
Hiroaki Nishio, Hiroshi Yamamoto1995 Volume 42 Issue 1 Pages 11-15
Published: January 15, 1995
Released on J-STAGE: July 12, 2010
JOURNAL FREE ACCESSThe magnetic field and temperature dependences of the magnetic aftereffect constant Sv were examined for the Sm2(Fe0.8Co0.2)17 N3.03 compression bonded magnet at a temperature range from 77 to 397K. Sv increases gradually with increasing the magnetic field. The temperature dependence of coercive force HCJ, for Sm2(Fe0.8Co0.2)17N3.03, Sm-Co and Nd-Fe-B magnets decrease with the increasing temperature. However, the temperature dependence of Sv for the Sm2(Fe0.8Co0.2)17N3.03 compression bonded magnet was reverse to HCJ, in contrast to Sm-Co and Nd-Fe-B magnets. The temperature variation of coercive force ΔHCJ/ΔT in these rare-earth magnets linearly decreases as the activation volume v increases. Larger v for low ΔHCJ/ΔA T values and smaller v for higher HCJ, values are necessary, so that balanced performance of HCJ, should be obtained by choosing appropriate v values.View full abstractDownload PDF (262K) -
Minoru Umemoto, Jindi Yien, Satoru Kakoo, K. Raviprasad, Isao Okane, S ...1995 Volume 42 Issue 1 Pages 16-21
Published: January 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSExchange spring magnets are a new class of permanent magnets consisting of exchange coupled hard and soft magnetic phases at nano meter scale. Such an exchange coupling helps these magnets to exhibit high coercive force as well as high saturation magnetization, resulting in a higher energy product. Recent surge in the research interest in this field has shown that the nitrides of rare earth-iron compound to exhibit good magnetic properties. Also, the application of mechanical alloying technique for the synthesis of the rare earth-iron compound is found to be more versatile. In the present study we have mechanically alloyed SmxFe100-X (X=7, 9, 11, 13). In the as milled condition α-Fe was found to co-exist with an amorphous phase. Heat treating the mechanically alloyed powder resulted in the formation of Sm2Fe17 compound (hard phase) and α-Fe (soft phase). The formation of the hard phase as a function of Sm content and heat treatment temperature is studied. The heat treated samples were nitrided for different duration and at various temperatures. The major and the minor hysterysis loops of these nitrided samples were measured and their magnetic properties were studied. Good magnetic properties were observed for alloys with 9at.% Sm. Improvements in the magnetic properties and thermal stabilities of the hard phase is studied by the substitution of Co, Cr and Si for Fe. It was found that Co substitution for Fe increases both the remanence and the coercivity, resulting in a higher energy product.View full abstractDownload PDF (1620K) -
Katsuhiko Igarashi, Taku Murase, Takeshi Nomura1995 Volume 42 Issue 1 Pages 22-26
Published: January 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDeterioration of initial permeability (μi) with frequency has been investigated with reference to chemical composition and microstructure on the MnMgZn ferrites. Gradual deterioration of μi with frequencies is serious with MnO addition on the MgZn ferrite. This is considered as a relaxation phenomenon. Relaxation time (τ) was calculated by using the relationships ω τ=1. Activation energies for MgZn and MnMgZn ferrites were 0.14eV and 0.36eV. respectively. These results indicate that the relaxation of μi for.MgZn and MnMgZn ferrites may be caused by the electron migration and cation migration, respectively.View full abstractDownload PDF (2552K) -
Osamu Kimura, Masafumi Matsumoto, Mitsuo Sakakura1995 Volume 42 Issue 1 Pages 27-33
Published: January 15, 1995
Released on J-STAGE: July 12, 2010
JOURNAL FREE ACCESSThe object of this study is to enhance the dispersion frequency of Z type Magnetoplum-bite ferrite with the composition of 2CoO⋅3BaO⋅12Fe2O3. Firstly, the substitution of of strontium ions with smaller ionic radius for some of barium ions in the formula 2CoO⋅(Ba1-xSrx)O⋅12Fe2O3 leads to the maximum value of μQ when x is 0.5. Secondly, when the iron content is shifted from stoichiometric value and hot-pressed in air or in an oxygen atmosphere in keeping x = 0.5, the sample with the composition 2CoO⋅3(Ba0.5 Sr0.5)O⋅10.8Fe2O3 revealed the best μQ value, especially for the sample hot-pressed in the oxygen atmosphere. Its resonance frequency corresponding to μ″ maximum extended to 2.5 GHz, which is sufficiently larger than the value of 1.4 GHz previously reported.View full abstractDownload PDF (366K) -
Tatsuo Fujii, Misuhiro Asano, Hiroshi Asaoka, Yoshinari Miura, Jun Tak ...1995 Volume 42 Issue 1 Pages 34-39
Published: January 15, 1995
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESS(100)- and (111)-oriented Fe3O4/CoO superlattices were prepared on MgO(100) and α-Al2O3(0001) singlecrystalline substrates, respectively, by activated reactive vapor deposition method. X-ray diffraction analysis suggests that the lattice spacing along the growth direction was contracted for the CoO layer but expanded for the Fe3O4 layer probably due to the lattice mismatch between these layers. The magnetostriction of CoO layers induced in-plane and perpendicular magnetic anisotropy in (100)- and (111)-oriented superlattices, respectively. Coercive force along the magnetic easy axis was increased with increasing the thickness of the CoO layer but decreased with increasing that of the Fe3O4 layer. Strong magnetic coupling between Fe3O4 and CoO layers made the Noel temperature of the CoO layer higher and showed the ferrimagnetic/antiferromagnetic exchange anisotropy.View full abstractDownload PDF (385K) -
Yoshihito Kawamura, Akihisa Inoue, Akinori Kojima, Tsuyoshi Masumoto1995 Volume 42 Issue 1 Pages 40-46
Published: January 15, 1995
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSFor the production of nanocrystalline soft-magnetic compacts with high saturation magnetization, we investigated the densification behavior of amorphous and nanocrystalline Fe86Zr7B6Cu1 (at.%) powders using a hot-pressing machine, and the magnetic properties of the compacts. The density of the compacts produced from the nanocrystalline powder was 90.4 %. However, nanocrystalline compacts with a high density of 99.9 % were obtained by hot pressing the amorphous powder under 1.5 GPa and 853 K. We constructed the densification map of the amorphous and nanocrystalline powders. The pressure required to produce dense compacts, which was estimated from this map, is 3.0 GPa for the production of amorphous compacts, and 4.4 GPa for the consolidation of the nanocrystalline powder into nanocrystalline compacts, and only 1.5 GPa for the direct consolidation of the amorphous powder into nanocrystalline compacts. The consolidation of the amorphous powder through the crystallization is the most appropriate method for the production of dense nanocrystalline compacts. The dense nanocrystalline compacts exhibited good soft-magnetic properties which were superior to those of Fe-based amorphous compacts, in addition to a high saturation magnetization of 1.56 T. The coercive force, effective permeability at 1 kHz and 0.8 A/m, and core loss at 10 kHz and 0.1 T were 33 A/m, 1300 and 37 W/kg, respectively.View full abstractDownload PDF (4317K) -
Shinichiro Ishibashi, Toshihiko Sato, Koichi Haneda, Masahiro Seki1995 Volume 42 Issue 1 Pages 47-52
Published: January 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe boiler as a steam generater is used in various field from heating for buildings to thermal power stations. In these boilers and solution in piping facility, scale or sludge is produced. Researches on the composition of these substances have been carried out, however, a detailed analysis of properties of iron compounds is not yet available. So, in this research, we looked especially at ferromagnetic substances. One particularly interesting finding was that these substances contain as much as approx. 20-25% of ferromagnetic particulates (ferrite) such as magnetite (Fe3O4). Average particle size of this ferrite is ultrafine particulate of 17-27nm. And value of saturation magnetization is 65-85emu/g by correcting the contented of calcite mixed and non-magnetic layer part on particle surface. And this value is nearly equal to Fe3O4 of bulk.View full abstractDownload PDF (1753K) -
[in Japanese]1995 Volume 42 Issue 1 Pages 54
Published: January 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (81K) -
Katsuhisa Tanaka, Kenichi Kashima, Koichi Kajihara, Kazuyuki Hirao, Na ...1995 Volume 42 Issue 1 Pages 55-60
Published: January 15, 1995
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSGlass transition temperature of ZnO-BaO-TeO2 glasses, which show optical second harmonic generation after the electrical poling, has been measured in order to discuss the relationship between second harmonic intensity and glass structure. The glass transition temperature decreases with a replacement of BaO by ZnO, indicating that the flexibility of glass structure increases with an increase in the content of ZnO. Hence, an orientation of ensemble of electric dipoles due to TeO4 trigonal bipyramid and TeO3 trigonal pyramid can take place more readily in the tellurite glass with high concentration of ZnO, leading to the high optical second harmonic intensity and large second-order nonlinear coefficient in the glasses with ZnO-rich composition. Furthermore, it is thought that preferential occurrence of electron polarization of Ba2+ hinders the orientation of tellurite structural units when the external electric field is applied. The very low second harmonic intensity of poled 15PbO⋅85TeO2 glass supports this speculation.View full abstractDownload PDF (348K) -
Tadashi Endo, Kuniharu Tanaka, Hirotsugu Takizawa, Masahiko Shimada1995 Volume 42 Issue 1 Pages 61-66
Published: January 15, 1995
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSTernary tellurite glasses were prepared by a conventional quenching method in the system TeO2-LiO0.5-YO1.5⋅IR spectra reveal that the glasses contain the following polyhedra: deformed TeO6 groups, TeO4-trigonal bipyramids, TeO3-trigonal pyramids, or combinations of these polyhedra. The highly addition of glass-network modifiers, especially Li+ ion, leads to a collapse of polyhedra networks. The intense emission peak, due to the transition 4S3/2-4I15/2' was found at 546 nm in tellurite glasses doped with Er3+ under 378 nm and 973 nm excitations at the room temperature. Upon excitation at 973nm, the emission shows a typical upconversion characteristic, indicating the quadratic profiles of the emission intensities against the exciting powers. The emission intensities tend to be dependent upon 378nm excitation, but independent of Er3+ concentration upon 973 nm excitation. The excitation and emission involve two photons process through the 4I11/2 level of Er3+ ion. Up conversion fluorescence is, also, enhanced at 547nm by the supplementary doping with Yb3+ ion.View full abstractDownload PDF (320K) -
Kazuo Suzuki, Naohiro Soga, Setsuhisa Tanabe, Teiichi Hanada1995 Volume 42 Issue 1 Pages 67-71
Published: January 15, 1995
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSUpconversion characteristics of Tm3+-Er3+ codoped tellurite glasses were investigated and the snsitization of Tm3+:1G4→3H6(480nm) luminescence and quenching of Tm3+:1D2→3F4(450nm) were observed by the 650nm pumping. The change of upconversion luminescence specta by Tm3+-Er3+ codoping was investigated as a function of rare-earth ions concentration. It is found that the intensity of Tm3+:480nm blue upconversion luminescence was largest in the case of Er3+/Tm3+=1-2. These results were discussed by considering the energy transfer efficiency between Tm3+:3H4→Er3+:4I9/2 and Er3+:4I13/2→Tm3+:3F4.View full abstractDownload PDF (296K) -
Yong Ding, Yoshinari Miura, Akiyoshi Osaka, Hisayoshi Toratoni, Yoshih ...1995 Volume 42 Issue 1 Pages 72-77
Published: January 15, 1995
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSLiNbO3 was crystallized with orientation along c-axis on the surface of a glass of the composition 35Li2O⋅0Nb2O5⋅35SiO2 (in mol%). The dense surface layers were composed of fibrous-grain crystallites, and the thicknesses were controllable by changing heating temperature and time. Kinetic analysis indicated that crystallization of LiNbO3 was diffusion controlled.View full abstractDownload PDF (1628K) -
Hiroyuki Nasu, Jun Matsuoka, Kanichi Kamiya1995 Volume 42 Issue 1 Pages 78-83
Published: January 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSSiO2 glass thin films doped with semiconductor microcrystals such as CdSe, CdTe and GaAs were prepared by the rf-sputtering technique. The concentration and mean diameter of the microcrystals were dependent on the relative surface area of the semiconductor chips on SiO2 glass target plate, and the size distribution was strongly influenced by the sputtering condition. The suitable condition for each semiconductor has to be individually determined. The quantum size effect was found from the blue shift of the optical absorption edge. The shift for CdSe-doped SiO2 glass thin films clearly deviated from the simple theoretical predictions based on the confined effects. Thus, introduction of Coulomb interaction and the influence of the dielectric constant of matrix were found to be necessary to interpret the experimental data.View full abstractDownload PDF (329K) -
Takafumi Atarashi, Akira Kishimoto, Katsuto Nakatsuka1995 Volume 42 Issue 1 Pages 84-89
Published: January 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMulti-layer thin mirrors were obtained easily by repeating dip coating followed by heat treetment. The condition of the heat treetment was 500°C, 10 minutes.
The mirror is composed of alternative seven layers of the titania and the silica on a quartz-glass substrate.
The phases of the titania and silica were amorphous. The refractive index was 2.1, and 1.45 for titania and silica respectively.
The muximum reflection of incident light of this layered film was 83% and was just the same as its theoretical value. The optical transmission data was in agreement with the spectra simulated by using above indicies.
The wave length of the maximum reflection of the film can be controlled by the thickness of each oxide layer, though controlling the alcoxide concentration of the coating solution at the stage of dip coating.View full abstractDownload PDF (316K) -
Takafumi Atarashi1995 Volume 42 Issue 1 Pages 90-94
Published: January 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSBlack powder, such as magnetite or metallic iron powder, absorbs incident visible light. But metallic silver-coated black powder reflects incident visible fight. The silver-coated powder was obtained by using electroless plating.
The silver layer on the black powder was composed of silver particles and the size of the silver particle was ranged from 5 nm to 80 nm.
When the amount of the metalized silver was small, silver perticles deposited like islands on the black powder. On the other hand, the large amount of silver particles deposited on the powder lead to formation of silver layer.
The color of the most bright silver-coated powder is pale yellow.
When the silver layer becomes thicker than the thickness in which the coated layer is opaque for incident visible light, the the brightness of the powder becomes almost same the constant value, and the color and the brightness of the powder were close to those of the silver powder.View full abstractDownload PDF (3500K) -
Ritsu Miura, Yasuo Endo, Rtuichi Sakamoto, Hirokazu Madarame1995 Volume 42 Issue 1 Pages 97-102
Published: January 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSPrevention of the deformation during debinding and sintering is a key issue to produce highly complex parts in acceptable dimensional accuracy by metal injection molding(MIM), since three-dimensionally complex compacts are very sensitive to such deformation.
In this paper, the deformation behavior of the injection molded thin-wall metal compact with complex geometry during debinding and sintering has been investigated in various placement of the specimens. Based on the results obtained, the factors influencing these deformation have been considered.
Debinding deformation occurs through the release of residual stresses generated in the compact during molding as well as through the viscous creep by gravity. The amount of deformation associated with the residual stress depends on the holding pressure at molding, while that due to the viscous creep depends on the rate of binder removal.
As one of the factors influencing the sintering deformation, a time lag of sintering shrinkage within the compact due to the temperature difference caused by the contact with the ceramic substrate has been cited. It has been also considered that the compact geometry, especially the presence of discontinuity or intersection, the creep by self-weight and the friction between the compact and the substrate cause the sintering deformation.View full abstractDownload PDF (3126K) -
Keizo Kobayashi, Kenji Miwa1995 Volume 42 Issue 1 Pages 103-107
Published: January 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSTi5Si3 powder was synthesized by mechanical alloying (MA) of Ti powder and Si powder using a vibrational ball milling under 35kPa Ar. When stainless steel was used as a vessel and balls for MA, the obtained MA powder was amorphous and included a considerable amount of Fe because of adhesive wear of MA balls.
ZrO2 ball forms coating layer on the surface of a ball in MA process, so that the contamination from MA ball to MA powder can be reduced. The Ti5Si3 powder milled for 720ksec with ZrO2 balls was not amorphous and contained Ti and Si crystal phase. WSi2 powder and MoSi2 powder were not synthesized by MA of W powder and Si powder or Mo powder and Si powder for 720ksec with ZrO2 balls.View full abstractDownload PDF (2297K) -
Yutaka Hiraoka, Tetsuji Hoshika1995 Volume 42 Issue 1 Pages 108-112
Published: January 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIn order to investigate the effects of specimen size on the ductile-to-brittle transition characteristics, three-point bend tests at temperatures from liquid nitrogen temperature to room temperature were carried out for recrystallized sheets of pure molybdenum with different specimen width and thickness. In this study the ductile-to-brittle transition characteristics of the material are represented by two parameters, critical stress and critical temperature.
The results are summarized as follows.
(1) In the case of specimen thickness being 1.0mm, the effects of specimen width ranging 4-1mm on the critical stress and critical temperature were almost negligible.
(2) In the case of specimen width being 4mm, critical stress and critical temperature of the specimens with specimen thickness ranging 1.0-0.5mm were almost the same. However critical temperature of the specimen with specimen thickness of 0.3mm was lowered, though critical stress was only slightly decreased.View full abstractDownload PDF (284K) -
Takashi Tokuhiro, Kazuo Ichii, Masao Yakushiji1995 Volume 42 Issue 1 Pages 113-117
Published: January 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe pitting potentials of amorphous NixZ100-x powders formed by mechanical alloying of crystalline powder of the component elements which have different electrochemical properties were measured in 3.5% NaCl solutions in accordance with JIS G 0577.
From the results obtained it was found that the pitting potentials of the amorphous powders were more noble than the potential at which Ni dissolves actively, and less noble than the pitting potential of Zr. It was also concluded that the measurement of pitting potentials could be a useful method to follow the mechanism of the amorphous formation in mechanically-alloyed powders.View full abstractDownload PDF (3754K) -
Takahiro Kaneyoshi, Teruo Takahashi, Yukinobu Hayashi, Muneyuki Motoya ...1995 Volume 42 Issue 1 Pages 118-121
Published: January 15, 1995
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSNb, Al, Ti, C and B powders were mechanically alloyed(MA) in an Ar gas atmosphere. The results of X-ray diffraction indicated that for the starting composition of Nb3Al, Nb solid solution was obtained in the early stage of MA process, thereafter it became to be amorphous. Nb3Al compound was obtained by vacuum heating of 72.0ks MA powders. Nb3Al and TiC were obtained in the system of the composition of Nb3Al-30vol%TiC by vacuum heating of 72.0ks MA powders. Furthermore, fine TiC particle dispersed Nb3Al composite was obtained by HIP processing of MA powders. TEM observation of the HIPed compacts revealed that TiC, which was more less than 0.1μm, precipitated on fine grained Nb3Al matrix.View full abstractDownload PDF (2894K)
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