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Volume 55, Issue 11
November
Displaying 1-10 of 10 articles from this issue
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Paper
Paper
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Bin Chen, Chishiro Michioka, Yutaka Itoh, Kazuyoshi Yoshimura2008 Volume 55 Issue 11 Pages 759-763
Published: 2008
Released on J-STAGE: December 16, 2008
JOURNAL OPEN ACCESSNi3AlCx was synthesized by two methods, argon arc melting and solid state reaction methods. X-ray diffraction measurements revealed that the samples prepared by the arc-melting method are in a single phase with the Cu3Au type crystal structure. In x >0.02, all the samples do not show the ferromagnetism but show Pauli paramagnetism while the samples prepared by the solid state reaction method show a tendency of ferromagnetism at about 280 K in the temperature derivative magnetization. From the 27Al NMR measurements, we found the absence of the magnetic phase transition for the samples with x =0.1 prepared by both methods. We conclude that for the samples prepared by the solid state reaction, the enhancement of the magnetization with a tendency of the ferromagnetism is extrinsic, which may be attributed to the possible deposition of Ni-based alloy.View full abstractDownload PDF (596K) -
Kazuhiro Hasezaki, Yasutoshi Noda2008 Volume 55 Issue 11 Pages 764-769
Published: 2008
Released on J-STAGE: December 16, 2008
JOURNAL OPEN ACCESSMinimum interlayer numbers of functionally graded materials (FGMs) is studied based on the empirical analysis of thermal stress due to the differences in the thermal expansion coefficient Δα and temperature ΔT between sintering and room temperatures. It is found the maximum Δα, ΔT, ΔαΔT and the minimum interlayer number necessary to produce a NiCr/Fly ash FGM structure without cracking are 4.0×10−6 K−1, 1080 K, 0.043 and 2, respectively. The criterion, ΔαΔT < 0.043, is derived and confirmed to be valid for available FGM systems.View full abstractDownload PDF (856K) -
Toru Shimizu, Kunio Matsuzaki, Kaoru Kikuchi, Naoyuki Kanetake2008 Volume 55 Issue 11 Pages 770-775
Published: 2008
Released on J-STAGE: December 16, 2008
JOURNAL OPEN ACCESSTo produce metal foam over 95 % porosity, the process using foamed polystyrene sphere as space holder was developed. This process includes the use of low cost metal powder, and the process itself is simple and easy. In this process, slurry of metal powder and water solution of PVA were prepared. The slurry was mixed with foamed polystyrene sphere, and the metal powder was coated on the surface of the sphere. This mixture was molded, frost and kept for 24 hours. The slurry was changed to gel and the defrosted mixture preserves the molded shape. The precursor obtained by this process was desiccated and sintered. All binder and polystyrene were decomposed prior to the sintering step, and thus the high porosity metal foam was obtained. Using stainless powders, the metal foams having the porosity ranging from 90 to 97 % were produced. Pore size could be controlled by changing the size of the sphere used. Productable size of the foam was limited by powder size and the size of sphere. Using this process, the production cost of high porosity metal foam could be decreased and large size steel foam are expected to be produced with a reasonable cost.View full abstractDownload PDF (1099K) -
Mitsuhiro Karakita, Junpei Koyama, Takahiro Komatsu, Masaaki Miyamoto2008 Volume 55 Issue 11 Pages 776-780
Published: 2008
Released on J-STAGE: December 16, 2008
JOURNAL OPEN ACCESSA new simple method of preparing β-FeSi2 sintered body using hot pressing is presented Fe and Si powders were mixed by ball-milling for 1 hour in an argon atmosphere. Mixtures of Fe and Si powders were hot-pressed at 1100°C for 1 hour under 46.8 MPa and heat treated at 850°C for 9 hours in an argon atmosphere. X-ray diffraction analysis showed that as hot-pressed samples were composed mostly of α-FeSi2 phase with small amount of ε-FeSi phase and their relative densities were more than 93 %. By using the method described above, β-FeSix samples with non-stoichiometric compositions of (1.80≤x≤2.30) were prepared, and their thermolelectric properties were investigated. The electric conduction type of the samples of which x values were smaller than 2.05 showed p-type and that of others showed n-type.View full abstractDownload PDF (757K)
Special Issue: Functional Ceramics
Summarization
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Yuichi Shimakawa2008 Volume 55 Issue 11 Pages 782
Published: 2008
Released on J-STAGE: December 16, 2008
JOURNAL OPEN ACCESSDownload PDF (100K)
Memorial Lecture of JSPM Award
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Hiroshi Kishi2008 Volume 55 Issue 11 Pages 783-789
Published: 2008
Released on J-STAGE: December 16, 2008
JOURNAL OPEN ACCESSRecent progress on multilayer ceramic capacitors (MLCCs) with Ni electrodes is reviewed from the viewpoint of non-reducible dielectric materials. Using intermediate ionic size rare-earth ions (Dy, Ho, Er, Y) doped BaTiO3 (BT) based dielectrics, highly reliable Ni-MLCCs with very thin layer about 1 μm have been developed. The effect of site occupancy of rare-earth ions in BT on the electrical properties and microstructure was studied systematically. It appears that the intermediate ionic size rare-earth ions occupy both A- and B-site in BT lattice and effectively control the donor/acceptor dopant ratio and microstructural evolution. The effect of raw BT powder characteristics, such as particle size and crystallinity on the microstructure as well as the electrical properties of MLCC with ultra thin active layers was also investigated. The dielectric constant at room temperature drastically decreased for the grain size of less than 200 nm. The MLCC samples using raw BT with high tetragonality (c/a) showed high dielectric constant and stable temperature characteristics. The synthesis of fine-grained and high crystalline BT particles by solid state process is also presented.View full abstractDownload PDF (1337K)
Paper
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Satoshi Kishida, Dong-Ying Ju2008 Volume 55 Issue 11 Pages 790-794
Published: 2008
Released on J-STAGE: December 16, 2008
JOURNAL OPEN ACCESSγ-Al2O3 coatings were prepared on aluminum-free SUS304 stainless steel by an electrophoretic deposition method. Both TG-DTA and Scanning Electron microscopy are used to study the adhesion property and morphological features of coatings. The results indicate that the thickness of coatings on SUS304 top reaches 3-5 μm without any exfoliation, which is prepared at optimize conditions. Catalytic properties of coated samples for NOx were highly enhanced as compared with the samples prepared by the dip coating method.View full abstractDownload PDF (1038K) -
Masateru Nose, Tokimasa Kawabata, Shouhei Ueda, Takekazu Nagae, Atsush ...2008 Volume 55 Issue 11 Pages 795-800
Published: 2008
Released on J-STAGE: December 16, 2008
JOURNAL OPEN ACCESSThe influence of sputtering conditions on the microstructure and mechanical properties of Al-O-N films was investigated using XRD, TEM and nano-indentation. The targets of sintered Al2O3 plate were sputtered in a mixture of argon and nitrogen using an r.f. sputtering apparatus of facing target-type sputtering. Nitrogen gas flow rate was controlled from 0 to 40 sccm under the fixed Ar gas flow rate (10 sccm). The substrate was heated up to ∼300°C. The highest hardness of 27 GPa was obtained for the Al-O-N film deposited at 300°C under 30 sccm of the nitrogen gas flow rate, which value is almost twice that of Al-O films.
XRD and SAED analysis of Al-O-N films suggested the existence of some phases; hcp-AlN, AlON and ι-Al2O3 phase may presented in the film. The dark-field TEM images of the Al-O-N films revealed that the film consists of very fine grains of ∼6 nm in diameter.
The Al-O-N film having the highest hardness has higher transparency of visible light than that of Al-O films. Even if the Al-O-N films was annealed up to 800°C for 1 hour in the air, mechanical properties were not changed, but decreased drastically after the annealing at 900°C.View full abstractDownload PDF (901K) -
Katsuhiro Nishiyama, Shigenori Utsumi, Keiko Itoh, Takanobu Nakamura, ...2008 Volume 55 Issue 11 Pages 801-806
Published: 2008
Released on J-STAGE: December 16, 2008
JOURNAL OPEN ACCESSSintered Fergusonites NdNbO4 and YNbO4 were prepared by the hot-press method and their density, bending strength, elastic properties, micro-Vickers hardness, fracture toughness, and damping properties were measured. The damping capacities of NdNbO4 and YNbO4 were 6-7 % at 1×10−3 of the maximum surface shear strain. They increased with the maximum surface shear strain and reached 17-20 %. The damping capacities of NdNbO4 and YNbO4 exhibited the maximum at room temperature, and decreased with increasing temperature. These values of damping capacities were higher than those of other representative ceramics. The microplastic strain of NdNbO4 and YNbO4 was caused at 10−5 MPa of stress. High damping behaviors of NdNbO4 and YNbO4 were caused by internal friction due to the movement of dislocations and twins which were observed by transmission electron microscopy.View full abstractDownload PDF (808K)
Errata (Vol.55, No.8)
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Kenji Metoki, Hiroki Koike, Toshiyuki Takahashi, Koji Hayashi2008 Volume 55 Issue 11 Pages 809
Published: 2008
Released on J-STAGE: December 16, 2008
JOURNAL OPEN ACCESSAbout the paper by Kenji Metoki et al. published in the August 2008 issue of the Journal, the authors requested that some errors of the original paper should be corrected.View full abstractDownload PDF (22K)
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