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Volume 46, Issue 2
Displaying 1-16 of 16 articles from this issue
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Effect of surface crack of alumina green compact on bending strength of sintered aluminaEiichi Sentoku1999 Volume 46 Issue 2 Pages 115-119
Published: February 15, 1999
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSMany ceramics have been developed for the uses for mechanical or electronic parts. The high strength ceramic with reliability is necessary for the field of industtrial material. The purpose of this paper is to study relations between the power to function on the tool edge during cutting an alumina-green compact and the strength of sintered alumina ceramic. The strength of alumina ceramic was examined by the three point bending test. The main results obtained are as follows; (1) In cutting an alumina-green compact, destructive crack propagates along the grain boundary or transgranularly. (2) The true bending strength or the fracture energy of alumina ceramic decreases by the big power cutting of the alumina-green compact.View full abstractDownload PDF (3620K) -
Hisakazu Tomino, Yoshihito Kondo, Tetsuro Tojo1999 Volume 46 Issue 2 Pages 120-124
Published: February 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSRecently, the porous cast-iron bonded (PCIB) diamond grinding wheel has been developed. Hence, it was thought that the grinding performance of the PCIB diamond grinding wheel depends on the porosity, which is the major property of a porous material. However, the influence of the porosity on the mechanical properties of the PCIB diamond grinding wheel has not been studied.
In this paper, the atomized cast-iron-diamond composite sintered bodies, which had several grain volume percentages and porosities, were made by the pulse electric current sintering method. The Young's moduli and the bending strengths of these sintered bodies were measured. The relationships between those mechanical properties and the structures of the sintered bodies were examined. The results were as follows:
(1) Both the Young's modulus and the bending strength of the composite sintered body increased as the porosity decreased.
(2) The diamond grain size did not affect the Young's modulus, and influenced the bending strength under the experimental conditions of this study.
(3) The Young's modulus depended on the diamond grain volume percentage. In the case where the atomized castiron sintered body (hereinafter referred to as the matrix) in the composite sintered body had the same porosity, the Young's modulus increased with increasing diamond grain volume percentage.
(4) The bending strength of the composite sintered body with the same porosity as in the matrix depended on the bending strength of the matrix.View full abstractDownload PDF (2122K) -
Wen-bo Du, Kiyohiko Tatsuzawa, Tatsuhiko Aizawa, Junji Kihara1999 Volume 46 Issue 2 Pages 125-130
Published: February 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe resintering behavior of swaged Al2O3 up to 98% reduction in area was investigated to discuss the intense coldworking effect in the green state. The relative density of resintered Al2O3 could be improved to be close to 99% theoretical density at 1573 K for 1 h, and negligibly small grain growth was observed when the relative density became less than 97.5%. Grain boundary diffusion was considered to be a dominant mechanism for resintering the swaged Al2O3 by calculating the activation energy.
The negligibly small grain growth was attributed to the homogeneous microstructure in the green state attained by the controlled fracture forming.View full abstractDownload PDF (419K) -
Takuya Tamura, Takahiro Kuriiwa, Hitoshi Takamura, Hazime Nakamura, Ma ...1999 Volume 46 Issue 2 Pages 131-137
Published: February 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSWhen hydrogen storage alloy is used as a negative electrode of nickel-metal hydride batteries, protium absorbing properties at a negative electrode is different from those at a gas phase because of the formation of oxide layers and a nickel-rich layer on the surface of the alloy due to charge and discharge. This paper investigates the effect of surface chemical etching on protium absorbing properties and electrochemical characteristics of LaNi5 alloys. Dilute HCI solution under 1% was used as etchants for the formation of a nickel-rich layer which works as a protection surface of the alloy against the KOH electrolyte. Protium absorbing properties of annealed LaNi5 samples which were etched shortly with 0.2N HCl or 0.02N HCl were better protium storage capacity than those of unetched annealed LaNi5 samples. Electrochemical characteristics of annealed LaNi5 samples which were etched for 60min with 0.02N HCl were better cycle stability than those of unetched annealed LaNi5 samples.View full abstractDownload PDF (2104K) -
Tatsuya Miyazaki, Koichi Kakizaki, Nobuyuki Hiratsuka1999 Volume 46 Issue 2 Pages 141-146
Published: February 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSMnZn ferrite thin films were prepared on quartz substrate buffered by ZnO under layer by r.f. magnetron-sputtering method. ZnO under layer film was formed as preferentially (001) oriented film in any thickness. When as-deposited Mn-Zn-Fe oxide films on ZnO under layer were annealed in reduced atmosphere at 800°C for 5 hours, single phase of spinel-type ferrite was formed. The films were preferentially crystal-oriented to [111] direction normal to the film. The thinner ZnO under layer successfully induced the (111) orientation in plane because of good lattice matching between ZnO and spinel phase. The film of Mn:Zn:Fe=23:9:68 composition had the value of saturation magnetization of 410 emu/cc. The relationship between composition and magnetization of the films was similar to that of the bulks. The (111) oriented films are expected to have high permeability and prominent frequency characteristics.View full abstractDownload PDF (2211K) -
Masahide Yamasaki, Kyung-Ku Choi, Kotaro Nakano, Yohtaro Yamazaki1999 Volume 46 Issue 2 Pages 147-150
Published: February 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSWe observed the microstructure of perovskite thin films, and compared the results with their colossal magnetoresistance (CMR) properties. Epitaxial or textured films of La1-xSrxMnyO3-δwere prepared by rf sputtering on (100)SrTiO3 and (110)sapphire single crystal substrates. The films were investigated by X-ray diffraction, magnetoresistance measurement, and transmission electron microscopy (TEM). The magnetoresistance of the films deposited on SrTiO3 substrate shows similar temperature dependence to that of bulk single crystals. The temperature dependence of the magnetresistance in the films on a sapphire substrate is different from that in bulk single crystals, that is, the magnetoresistance decrease monotonously with increasing temperature. We revealed by TEM observations that the films on SrTiO3 substrate grew epitaxially with a number of defects, however, the films on sapphire substrate grew with a columnar structure and showed no epitaxy. Therefore, the difference in the MR properties is attributed to the lattice mismatch between films and substrates.View full abstractDownload PDF (3702K) -
Akira Nagatomi, Shinichi Kikkawa, Toru Hinomura, Saburo Nasu, Fumikazu ...1999 Volume 46 Issue 2 Pages 151-155
Published: February 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIron nitrides were prepared by nitrogenizing α-iron in ammonia gas at temperatures from 100°C to 700°C. In the case using iron foils as a starting material, Fe2-3N and Fe4N were formed as a main crystal phase at the temperature ranges of 450-700°C and 250-400°C, respectively. A crystal phase like to Fe16N2 was formed at 210°C, but its XRD and Mössbauer data were too insufficient to identify as Fe16N2. While bulk Fe16N2 was formed by nitrogenizing iron fine powder with the diameter of about 20nm at 110°C for 10days, but small amounts of Fe3N coexisted as a second phase with Fe16N2 at 120°C for 10days. Crystal structure of Fe16N2 was refined by Rietveld method. The average magnetic moment of three kinds of Fe atoms in Fe16N2 was evaluated to be 2.52μB on the basis of its Mossbauer data, the value of which was larger by 15% than the magnetic moment of α-Fe. The saturation magnetization of the Fe16N2 powder was also larger by about 14% than that of the α-Fe powder before nitrogenizing.View full abstractDownload PDF (490K) -
Katsushi Kusaka, Takahiro Komura, Tetsuya Kondo1999 Volume 46 Issue 2 Pages 156-162
Published: February 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe objective of this study is mainly to evaluate PM ferritic stainless steel as magnetic shielding plate, comparing with PM PB-permalloy. In this case, PM plate thickness and sintering temperature (1173-1623K) were employed as parameters to optimize DC/AC (≤10kHz) magnetic shielding effect of materials, including magnetic measuring apparatus arrangement.
The results obtained in these conditions were summarized as follows:
(1) DC magnetic field is allowed to attenuate to a saturate level by using PM plate with 4mm thick which is sintered at 1273K at the lowest, while the saturate value decreases with the distance (r) from a magnetic source.
(2) AC magnetic field also is allowed to attenuate to a saturate level by using PM plate with 4mm thick which is sintered at 1373K at the lowest, although the saturate value differentiates between the frequencies of 1 and 10 kHz.
(3) Magnetic attenuation (dB) is fairly enhanced when a covering of the high-μ permalloy sheet is put on the periphery of PM plate in DC and 1 kHz range, although it is not effective in higher frequency range.
(4) Bend strength of PM plate shows a higher value by being sintered at higher temperature (ex.-200MPa at 1373K), untouched by the direct influence of material itself.
(5) PM ferritic stainless steel proved to have almost the same magnetic shielding effect as PM PB-permalloy, when sintered at 1373K or higher, and consequently, to be used as porous, corrosion-resistant magnetic shielding alloy.View full abstractDownload PDF (2170K) -
Kunio Matsuzaki, Akihisa Inoue1999 Volume 46 Issue 2 Pages 163-166
Published: February 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe La0.85Sr0.15Mn oxides with a perovskite structure and a negative magnetoresistance were easily prepared by oxidation of melt-quenched alloy tapes in air. The perovskite structure was obtained by oxidation at over 1073K. The magmetoresistance ratio at room temperature increase with oxidation temperature and reached 5% at 1373K. The annealing in O2 atomsphere enhanced the magnetoresistance ratio to 10%. Therefore, the oxidation process of the melt-quenched alloy is useful for the preparation of perovsky type La0.85Sr0.15Mn oxide with a negative magnetoresistance.View full abstractDownload PDF (1521K) -
Toshihiko Sato, Shinichiro Ishibashi, Takayuki Kimizuka, Koichi Haneda ...1999 Volume 46 Issue 2 Pages 167-171
Published: February 15, 1999
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSIn order to study the effect of ultrafine ferrite particles on the suppression of the growth of turfgrass mold, some ferrite characteristics hava been studied and the trial experiments on the suppressive effects by the ferrites have been studied. Several kinds of ultrafine ferrite particles were prepared by coprecipitation. The lattice constants of these ferrite were almost the same as those of the bulk ferrites. The average crystal sizes of these ferrite particles were less than 30nm which was coincident with the values obtained by TEM observation. Values of the saturation magnetization, σ5 of the ferrites prepared by coprecipitation were less than those of the bulk ferrites. This is attributed to the existence of magnetic inactive surface layer on the ferrite particles. The coecive force, IHc, of these ferrites was relevant to the magnetic anisotropy constant, K1, of the bulk ferrites. For MnFe2O4 and ZnFe2O4, the suppression of the growth of turfgrass mold could be observed at 10°C but not so clearly observed at 25°C. For Ni0.5Zn0.5Fe2O4, the suppression of the growth of turfgrass mold was observed at both 10°C and 25°C, especially at 25°C, about 40% suppression was observed.View full abstractDownload PDF (3647K) -
[in Japanese]1999 Volume 46 Issue 2 Pages 174
Published: February 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (100K) -
Takayuki Shimizu, Kyota Uheda, Hirotsugu Takizawa, Tadashi Endo, Masah ...1999 Volume 46 Issue 2 Pages 175-179
Published: February 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSTi4+ activated zirconia (ZrO2) has been known as a phosphor, which has a broad emission band peaking at 490nm and an afterglow lasting for several minutes. The visually detectable emission due to afterglow would be much improved by means of increasing a fluorescent intensity or forming traps that have suitable depth below a conduction band of ZrO2. We first examined the dependence of the luminescent intensity on coordination number for luminescent centers in three phases and temperature prepared phosphors. 0.1% Ti4+ activated monoclinic ZrO2 has the highest emission intensity as compared to SrZrO3:0.1%Ti and tetragonal ZrO2:20%Y2O3, 0.1%Ti. The coordination number of Ti4+ in a monoclinic ZrO2 is 7. Above the calcination temperature of 1200°C, luminescent intensity of the monoclinic ZrO2 phosphor sharply increased through phase transition. It was also observed that the persistence of afterglow depended upon the concentration of the traps created at high temperature. The traps were investigated by measuring thermoluminescence spectra. We discuss a mechanism of afterglow for the monoclinic ZrO2 phosphor. On the basis of these results, we tried to synthesize Ti4+ activated hafnia (HfO2), and measured luminescent properties.View full abstractDownload PDF (467K) -
Xinrong Wang, Hiroshi Masumoto, Yoshihiro Someno, Toshio Hirai1999 Volume 46 Issue 2 Pages 180-184
Published: February 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSAlternating TiO2/SiO2 multilayer optical films were fabricated on BK7 glass and Si (100) substrates by helicon plasma sputtering at room temperature. Optical and structural characterization of monolayers of TiO2 and SiO2 films, and their multilayers have been performed. The results of structural analysis show that the TiO2 and SiO2 films have a homogeneous and amorphous microstructure. Auger electron spectroscopy (AES) and transmission electron microscopy (TEM) observations reveal that TiO2/SiO2 multilayer films have well-defined interface. Five layers of alternating TiO2 and SiO2 exhibit maximum reflectance of 87% around the central wavelength of 800 nm which agrees well with the theoretical result.View full abstractDownload PDF (3153K) -
Daisuke Nagai, Minoru Osada, Masato Kakihana1999 Volume 46 Issue 2 Pages 185-188
Published: February 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSPowders of CuMO2 (M=Fe, Al, Y, Ga) with delafossite structure were synthesized by a gel technology using citric acid (CA) as a complexant. Heating of a mixed solution of CA, H2O and the constituent metals at 130°C gave a brown transparent gel. The gel was preheated at 350°C to give a powder precursor which was subsequently converted to oxides by heat-treating it at 700°C-1050°C for 12h either in N2 or in air. X-Ray diffraction and Raman scattering analyses showed that all the samples are virtually of single-phase without any indication of secondary phases. Pure CuMO2 was successfully synthesized by the CA-based gel technology at lower temperature and with shorter sintering time when compared with those for the conventional solid-state reaction technique.View full abstractDownload PDF (251K) -
Shinichi Kikkawa, Hiroshi Kanasaki, Masao Takahashi, Adhikary Kalyan, ...1999 Volume 46 Issue 2 Pages 189-193
Published: February 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSFormation of both (Zn1-xInx)O1+x/2 solid solution and (ZnO)mIn2O3 compound was investigated by firing the precipitates through mixed aqueous solution of Zn and In nitrates. The solid solution range was enlarged to 15% by its gel formation adding citric acid. The homologous (ZnO)mIn2O3 compound (m>12) with very long interlayer distance precipitated around 650°C by heating the homogenous solid solution. It gradually decomposed to the compounds with m<12 and finally crystallized as a compound with the corresponding starting m-composition. Its thin film was prepared by dip coating method using diethylene glycol as a solvent. The film fired at 600°C was transparent in a wavelength range longer than 400nm. Its electrical resistivity gradually decreased to ca. 0.01Ωcm with the amount of doped In.View full abstractDownload PDF (422K) -
Toshiya Watanabe, Kazuhito Hashimoto1999 Volume 46 Issue 2 Pages 194-202
Published: February 15, 1999
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSWe report photo-generation of highly hydrophilic surface of titanium dioxide. The photo-induced hydrophilicizing is achieved by photo-generation of Ti4+ to Ti3+ at definite sites on the surface, resulting in preferential adsorption of hydroxyl groups on corresponding oxygen vacant sites. We also report the photo-generation of titanium dioxide amphiphilic surface on definite photo illumination condition. The unique character of this surface is ascribed to the microstructure of hydrophilic and oreophilic domain. The hydrophilic or amphiphilic titanium dioxide coating can be applied for antifogging mirror or glass and also self-cleaning paint for various industrial materials. Several commercial applications including antifogging automobile side-view mirror or self-cleaning exterior ceramic tile has been starting to hit the market.View full abstractDownload PDF (5446K)
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