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Volume 45, Issue 1
Displaying 1-18 of 18 articles from this issue
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[in Japanese]1998 Volume 45 Issue 1 Pages 2
Published: January 15, 1998
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (103K) -
Masahiro Nawa, Keiichi Yamazaki, Tohru Sekino, Koichi Niihara1998 Volume 45 Issue 1 Pages 3-12
Published: January 15, 1998
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSTo develop a new attractive ceramic material in which both high strength and high toughness might be achieved, we have established the new concept of an interpenetrated intragranular nanostructure based on the general design of the nanocomposites. The composite system designed according to the above concept possesses a novel microstructural feature. That is, for the composite composing of A and B phases, either nanometer sized A particles or equivalent sized B particles locate within the micron sized B grains or A grains, respectively. By applying the above material design, we succeeded to achieve a simultaneous improvements in strength and toughness for both Y-TZP and Ce-TZP based composite systems. This progress breaks through the strength-toughness tradeoff relation essentially existing in transformation toughened zirconia and its composite materials. In this paper, realized interpenetrated intragranular nanostructure along with forming process and mechanical properties will be described.View full abstractDownload PDF (12012K) -
Shinichi Kikkawa1998 Volume 45 Issue 1 Pages 13-19
Published: January 15, 1998
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSMaterial interaction is very important to find out new materials and interesting properties. Inorganic layered materials are very useful in this respect. Intercalation is one of the important properties of layered compounds. Preparation and properties are reviewed on various kinds of intercalation compounds. Further developments can be expected by controlling its microstructure in various applications such as lithium rechargeable battery. Mechanical interaction also apparently appeared on layered compounds such as high Tc cuprate oxide superconductors and misfit layered sulfides. The interaction induces oxygen or sulfur defects in their layered sublattices to reduce their mechanical stress. New compounds were also prepared applying high pressure synthesis on these layered compounds. Sputter deposited multilayered thin film is also expected to be very interesting as a functional inorganic layered material. A possibility was found out for a giant magnetization at the interface of Fe/AIN multilayer.View full abstractDownload PDF (573K) -
Takashi Goto, Takashi Ono, Toshio Hirai1998 Volume 45 Issue 1 Pages 20-24
Published: January 15, 1998
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSIridium-carbon composite films were prepared by metalloorganic chemical vapor deposition (MOCVD) on yttria stabilized zirconia (YSZ) substrates using an iridium acetylacetonate precursor. The films prepared without oxygen gas addition were black-colored and contained 35 to 70vol% carbon. The carbon was amorphous surrounding iridium grains of 1 to 3 nm in diameter. The Ir-C films showed excellent electrical and catalytic properties for YSZ as a reversible electrode at less than 800K. The impedance associated with the YSZ/Ir-C interface was about 1/3 to 1/5 smaller than that of sputtered Pt electrodes at 773K. By adding a small amount of oxygen gas in the source gases, the carbon content in the films decreased significantly accompanying grain growth of Ir and degradation of electrical performance. The output current using the Ir films containing a trace of carbon (about lmass%C) as electrodes was still four times greater than that using the Pt electrodes at 773K.View full abstractDownload PDF (5069K) -
Junichi Hojo, Koji Eto, Motohiro Umezu, Kazushi Kishi, Seiki Umebayash ...1998 Volume 45 Issue 1 Pages 25-30
Published: January 15, 1998
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSFine Si3N4 powder and Si3N4-TiN composite powder were prepared by vapor phase reaction method, and hot-pressed to investigate the effects of sintering condition and TiN inclusion on the microstructure and mechanical properties of sintered bodies. The prepared powders were fine with the size below 0.05μm. Hot-pressing was conducted at 1800-1850°C in N2 (1 atm) with 6wt% Y2O3 and 2wt% Al2O3 as sintering aid. When fine Si3N4 powder was sintered at 1800°C, the sintered body had a fine-grained microstructure. By increase in temperature to 1850°C, rod-like grains grew in the fine matrix, resulting in an increase in fracture toughness. Fine TiN particles were dispersed in Si3N4 matrix by sintering of Si3N4-TiN composite powder, indicating the formation of nanocomposite. In the composite system, the growth of rod-like grains was observed even at 1800°C. This suggests the acceleration of Si3N4 grain growth by TiN inclusion. The composite had a high fracture toughness.View full abstractDownload PDF (4372K) -
Kyota Uheda, Masayuki Takahashi, Hirotsugu Takizawa, Tadashi Endo, Mas ...1998 Volume 45 Issue 1 Pages 31-35
Published: January 15, 1998
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSWe newly synthesized AlN using urea and aluminium chloride as the starting materials. By directly introducing aluminium chloride into a melted urea at 135°C, urea-precursor was formed under a non-aqueous condition and then no γ-Al2O3 was observed in any calcination steps. As a result, well-crystalline AlN powder was obtained by the pyrolysis of urea-precursor above 900°C under a stream of N2 gas for lhour, In this process the urea-precursor decomposed above 350°C, and the formation of AlN skeleton with a layer structure occurred above 800°C. The total yield of AlN powder based on the Al atom was only 80% due to production of volatile Al(NH3)6AlH4C12 as a by-product. The AlN powder was characterized by X-ray diffraction, infrared spectroscopy and scanning electron microscopy (SEM). Morphological observation of the AlN powder by mean of SEM revealed large particles of about 30-μm diameter, which consisted of ultrafine particles of less than 1-μm diameter. In our report we also discuss the preparation and decomposition processes of urea-precursor for the synthesis of AlN.View full abstractDownload PDF (1777K) -
Masanori Kikuchi, Sung-Baek Cho, Junzo Tanaka, Yoshihisa Koyama, Takay ...1998 Volume 45 Issue 1 Pages 36-40
Published: January 15, 1998
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThermoplastic composites of β-tricalcium phosphate (TCP)/copolymerized poly-L-lactide (CPLA) were prepared by a heat kneading method and evaluated by XRD, FT-IR, three-point bending strength test and SEM. The composites were white and no structural changes were detected in TCP powder mixed with CPLA by XRD. Their compacts had a three-point bending strength of 51.26±6.34 MPa, a fracture strength of 52.64±2.975 MPa and a Young's modulus of 5.18±1.11 GPa. From SEM observation, TCP and CPLA adhered well, and mechanical fracture took place in both CPLA transgranular and TCP-CPLA intergranular regions. The IR absorption band of the polyester C=O double bond gradually shifted to lower wave numbers with increasing TCP content in the composites. This result suggested the formation of a Ca-O(=C) bond between TCP and CPLA which preserved the mechanical strength of the composite, almost independent of that of CPLA.View full abstractDownload PDF (4186K) -
[in Japanese]1998 Volume 45 Issue 1 Pages 42
Published: January 15, 1998
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (84K) -
Nobuyuki Hiratsuka1998 Volume 45 Issue 1 Pages 43-52
Published: January 15, 1998
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSAcicular barium ferrite, cobalt ferrite and crystal oriented manganese zinc ferrite particles were prepared using the acicular α-FeOOH as the starting material. The crystal structure and magnetic characteristics of these fine particles were investigated in detail. Acicular barium ferrite fine particles doped with Co2+ ions and Ti4+ ions were fabricated by a conventional sintering method. The BaCoxTixFe12-2xO19 particles consisted of some grains and their c-axis were aligned along the short axis of the acicular particles. The output waveform of the acicular barium ferrite magnetic tape signified that it had perpendicular magnetic anisotropy. Acicular cobalt ferrite fine particles were prepared from acicular α-FeOOH and C10H14O4Co⋅2H2O. The particles had coercivity of 1 kOe (80kA/m) and magnetization values of 67 emu/g (0.45Wb/m2). The output of the magnetic tape made of the acicular particles, with long axis of 0.4μm was greatlly enhanced in the high density recording. The acicular Mn-Zn ferrite fine particles composed of 65.6mol. %Fe, 21.9mol. %Mn and 12.5mol. %Zn were made by conventional sintering method. The fine particle was made up of several crystallites with long axis of 0.2-1.0μm. These fine particles were pressed in an applied magnetic field and then sintered at 1250°C for 4hrs in air. The oriented Mn-Zn ferrite exhibited strong crystal orientation similar to the single crystal of it.View full abstractDownload PDF (10757K) -
Yuetsu Ikeda, Motoi Kumagai1998 Volume 45 Issue 1 Pages 53-57
Published: January 15, 1998
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe sensitivity of the magnetic property to the external stress in NiCuZn ferrite was examined from the relationship between stress and permeability. In the production process of inductors, external stress is applied to the NiCuZn ferrite core by molding the resin, which is a protection against humidity or shock. As the permeability of NiCuZn ferrites are very sensitive against the external stress, the inductance of inductors changes very easily by the applied stress. This change has been recognized as the barrier to produce the inductors with a narrow inductance tolerance. We found the best way to control the stress-sensitivity of permeability in NiCuZn ferrite by the addition of oxide such as SiO2, and the inductance change can be completely explained from the residual stress caused by the difference of coefficients of linear thermal expansion between spinet phase (magnetic) and second phase (non-magnetic). By this new process, we succeeded in developing "Stress-insensitive Ferrite", and the mass production of the inductors with a narrow inductance tolerance.View full abstractDownload PDF (1881K) -
Tatsuo Fujii, Hiroshi Asaoka, Makoto Nakanishi, Jun Takada1998 Volume 45 Issue 1 Pages 58-62
Published: January 15, 1998
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe structural, electric and magnetic properties of (100)-oriented Fe3O4/NiO and Fe3O4/CoO superlattices on MgO(100) have been studied. The films were prepared by an activated reactive evaporation method. The lattice constants of each layers were a little changed from the bulk values due to a lattice mismatch with the substrate. The Fe 2p XPS of both Fe3O4/NiO and Fe3O4/CoO interfaces suggested the formation of stoichiometric Fe3O4. The saturation magnetizations (Ms) of Fe3O4/MO superlattices were compared with that of a Fe3O4 thin film as a function of the thickness of MO layers. The reduction in Ms of Fe3O4/NiO could be linked with the large exchange coupling with NiO. While the increase in Ms of Fe3O4/CoO was probably caused by the ferromagnetic coupling of the CoO interface with the Fe3O4 layer.View full abstractDownload PDF (433K) -
Shinichi Kikkawa, Hideyuki Sugiyama, Masao Takahashi1998 Volume 45 Issue 1 Pages 63-67
Published: January 15, 1998
Released on J-STAGE: July 12, 2010
JOURNAL FREE ACCESSAmorphous Si-Fe-N thin films were prepared by reaction cosputtering of variable numbers of Si chips on a Fe target with nitrogen sputter gas. They were homogeneous amorphous having both local structures similar to zinc blende type γ′′′-FeN0.91 around Fe atoms and also to Si3N4 around Si atoms. Fine particles of α-Fe were precipitated to show ferromagnetism by thermal decomposition of γ′′′-FeN0.91 like local structure above 400°C in hydrogen atmosphere. Weaker ferromagnetic component such as Fe3Si was formed above 600°C. Thermal instability of iron nitride was slightly improved by forming the Si-Fe-N amorphous material.View full abstractDownload PDF (372K) -
Hidehiko Kobayashi, Hikaru Minowa, Yoshinori Yamamoto, Koichi Kakizaki ...1998 Volume 45 Issue 1 Pages 68-72
Published: January 15, 1998
Released on J-STAGE: July 12, 2010
JOURNAL FREE ACCESSThe most suitable producing conditions and degree of densification of sendust (Fe-Si-Al alloy) coated with magnetite powders were investigated from the standpoint of the thermal decomposition. Ferrous formate powders obtained by the precipitation method were used for the coating material of commercial sendust powders. Sendust powders coated with magnetite powders were successfully prepared by pyrolyzing the mixture of fine ferrous formate powders and sendust powders with weight ratio of 1 at 400-1000°C for 1h. The thermal stability of the coated sendust powders under a continued heating at 700-1000°C in a CO2 gas flow was significantly high. The degree of densification of the compacts composed of the coated powders and an additive of excess magnetite was higher than those of the compacts with only coated powder, when fired at 1000°C for 5h.View full abstractDownload PDF (6209K) -
Shinichiro Ishibashi, Toshihiko Sato, Koichi Haneda, Masaru Yokoyama, ...1998 Volume 45 Issue 1 Pages 73-76
Published: January 15, 1998
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSBoilers are used to generate steam in many field such as building and thermal power generation. Substances precipitated from the circulating water through boilers and their piping during the course of evaporation such as sludge take place the obstruction to the flow and the lowering of the thermal efficiency of steam. New method of the removal and recovery of substances adhered to the pipe walls is described in this study in which the Lorentz force generated by equipping a magnet at the outer side of piping and controlling magnetic field is given. From fluorescent X-ray spectrographic analysis, X-ray diffraction, and magnetic measurement, the major component of the substances adhered to the pipe walls was identified as containing a mixed the magnetic Fe3O4 compounds of Zn, Cu and Si. Experimental results show that the sludge is more easily removed in the case of the magnet being equipped than in the other case. Total amount of removed scales by the magnet after two months has resulted in four times in weight compared with the case without the magnet.View full abstractDownload PDF (1730K) -
Seiichi Hosokawa, Sachio Toyota, Osamu Yamashita, Kunio Okimoto1998 Volume 45 Issue 1 Pages 77-81
Published: January 15, 1998
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSInfluences of pulverized particle size (0.67, 0.95, 1.14 and 1.39, μm) and magnetic field (0, 239, 478, 716 and 915kA/m) during compacting on the degree of alignment of Sr-ferrite were investigated using X-ray pole figure. Degrees of alignment of the compacted green bodies with average particle sizes of 0.95, 1.14 and 1.39 μm are saturated in a magnetic field of 239kA/m parallel to the compacting direction. To the contrary, applying the magnetic field perpendicular to the compacting direction, they are saturated in a magnetic field of 478kA/m. In the magnetic field lower than 478kA/m, degrees of alignment of the parallel configuration are higher than those of the perpendicular configuration, which is independent of particle size. In particular, at a small particle size of 0.67 μm, degree of alignment of the parallel configuration tends to be higher than that of the perpendicular configuration under any applied field.View full abstractDownload PDF (4239K) -
Koichi Kakizaki, Eiichiro Niizuma, Nobuyuki Hiratsuka1998 Volume 45 Issue 1 Pages 82-85
Published: January 15, 1998
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSBarium ferrite films were prepared by r.f. diode sputtering on AlN underlayers, and their crystal orientation and magnetic properties were investigated. The AlN underlayers, well oriented in c-axis, with the thickness of around 3000-5000Å were deposited at room temperature. On that AlN underlayer with the thickness of 5000Å, the barium ferrite films were deposited. As the deposited barium ferrite films were not crystallized, they were post-annealed at the temperatures between 600°C and 900°C for 18 ks in air. When the film was annealed at 650°C or more, the hexagonal crystalline of barium ferrite was improved and its [001] axis slightly lying perpendicular to the film surface was recognized. The superior orientation of [001] axis may be presumed to be caused by the effect of AlN underlayer. However, its orientation was not perfectly uniaxial, because of the use of incomplete crystalline AlN underlayers. On the other hand, perpendicular magnetic anisotropy of the barium ferrite films deposited on the AlN underlayers was enhanced, owing to the effect of the underlayers.View full abstractDownload PDF (324K) -
Nobuyuki Hiratsuka, Makoto Yamamoto, Koichi Kakizaki1998 Volume 45 Issue 1 Pages 86-90
Published: January 15, 1998
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSCrystal oriented manganese zinc ferrites were made from acicular manganese zinc ferrite fine particles. The acicular manganese zinc ferrite fine particles were prepared by a conventional sintering method. The acicular fine particles had the size of the long axis of about 4μm and the aspect ratio of about 16, respectively. To orient the acicular particles magnetically, they were pressed and formed to a shape under the magnetic field of 955kA/m by wet method. The green compact was sintered at 1250°C for 14.4ks in air, then cooled in nitrogen atmosphere. The crystal orientation of the sintered body was as strong as that of the single crystal manganese zinc ferrite. Moreover, crystal oriented manganese zinc ferrite troidal cores added with SiO2 and CaO were prepared, and then the frequency dependence of initial permeability of them were measured. The troidal core with the addition of 0.25wt%: SiO2 and 2.95wt%: CaO had the initial permeability of 1200 at 2MHz. The high value of the initial permeability may be caused by uniaxial crystal orientation and high resistivity phase formed by the additives.View full abstractDownload PDF (3021K) -
Shigetoshi Muranaka, Toshihiko Shigematsu1998 Volume 45 Issue 1 Pages 93-97
Published: January 15, 1998
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIndium oxide films were reactively deposited on the indium oxide substrates at 25-100°C. The influence of the substrate on the film structure and the physical properties was studied. The structure of the films was greatly dependent of the freshness of the substrate surface. Crystallized films could be deposited even at room temperature on the fresh substrates. On the air-exposed substrates, films were amorphous at room temperature, and partially crystallized at the higher substrate temperatures. The influence of the substrate on the electrical resistivity and optical transmission of the films was described. The effect of the heat-treatment of the air-exposed substrates on the film structure was also studied. Further, the contamination of the substrate surface was investigated by X-ray photoelectron spectroscopy. The results suggested that the surface of the substrates was refreshed by heating in vacuum at and above 300°C.View full abstractDownload PDF (335K)
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