巻号一覧
49 巻, 7 号
選択された号の論文の14件中1～14を表示しています
- |<
- <
- 1
- >
- >|
-
Ritsuko Tsuzuki, Yasuhiro Saiki, Sho Kataoka, Eiji Yuasa2002 年 49 巻 7 号 p. 565-569
発行日: 2002/07/15
公開日: 2009/05/22
ジャーナル フリーAmorphous Al100-xNi0.6xZr0.4x(X=30, 35 and 40) alloys were prepared by double mechanical alloying, and the obtained amorphous alloy powders were consolidated at various compacting temperatures by vacuum hot pressing. Changes of thermal stability, mechanical properties and microstructure of the compacts with the compacting temperature were measured. As a result, amorphous powder double mechanically alloyed begins to crystallize at 670-730K, while the compacts consolidated by the vacuum hot pressing at same temperature range is kept amorphous state. Also both the rupture strength and maximum deflection in the bending for the compacts reach the maximum value when they are consolidated at 750-800 K. In addition, the structure of amorphous phase in the compacts partially begins to crystallize, at the same compacting temperature range, to form ultra fine grains with the composition of Al40Ni51.5Zr8.5 whose average diameter is about 20nm, dispersed through the amorphous matrix.抄録全体を表示PDF形式でダウンロード (1612K) -
Shigetoshi Muranaka, Toshihiko Shigematsu2002 年 49 巻 7 号 p. 570-575
発行日: 2002/07/15
公開日: 2009/05/22
ジャーナル フリーZn2In2O5 films were reactively deposited with assistance of rf discharge in the oxygen pressure of 3×10-2 Pa and at substrate temperatures of room temperature and 320°C. The applied rf power was varied from 0-450W. The influence of the rf power on the film structure and the physical properties was studied. At 320°C, crystallized films could be deposited at and above 100W, while at 25°C, the films were crystallized above 300W. The crystallized films deposited at 320°C and at 100-250W exhibited the highest electrical conductance with the resistivity of below 10-3Ωcm and the excellent light transmittance of averagely 85% in the visible light range. The optical band gap for the films was determined. The value was in the range of 3.42-3.58eV.抄録全体を表示PDF形式でダウンロード (2058K) -
Ken Hirota, Kazuya Iketani, Masaru Yoshinaka, Osamu Yamaguchi2002 年 49 巻 7 号 p. 576-580
発行日: 2002/07/15
公開日: 2009/05/22
ジャーナル フリーLanthanum aluminum oxide LaAlO3 is formed at low temperatures (-870°C) from an amorphous material prepared by the hydrazine method. Powder characterization has been conducted using XRD, DTAITG, TEM, and BET method; LaAlO3 powders heated at 900°-1500°Crevealed that they consisted of submicrometer-sized translucent particles. They were sintered at 1800°C for 2h in air, dense ceramics with a 96.4% of theoretical have been obtained from the powder calcined at 1200°C. They exhibit the microstructure composed of well-developed grains (-140μm) with intergranular and intragranular pores of-13 and-7μm, respectively. Electric property has been evaluated; their dielectric constant at room temperature is 36.5±1.抄録全体を表示PDF形式でダウンロード (4234K) -
鹿谷 昇, 前田 英司, 小松 将博, 渡辺 征夫2002 年 49 巻 7 号 p. 581-587
発行日: 2002/07/15
公開日: 2009/05/22
ジャーナル フリーWe have prepared 85ZnO-10TiO2-5NiO ceramics by the spark plasma sintering (SPS) method aiming at appearance of remarkable increase in positive temperature coefficient of resistivity (PTCR). The specimens are found to have microstructures composed of small grains and neck-contacts. The PTCR characteristic is obtained when the specimens are oxidized by annealing over about 33 hours at 900°C, and becomes remarkable when the characteristic is measured in a reducing atmosphere of N2 gas. Especially for annealing during about 75 hours, the resistivity in the N2 atmosphere is found to increase markedly in a temperature range over 260°C, resulting in a peak value of 1.5×102Ωcm at about 380°C large by 3.5 order of magnitude compared to about 0.04 Ωcm in a temperature range below the Curie point of 260°C. In order to study mechanisms by which such remarkable PTCR is observed, we have measured Seebeck coefficients of specimens. When the specimens are annealed, space-charge-layers are formed around the surfaces of neck-channels between grains by trapping of carrier electrons due to absorption of oxygens to ZnO and TiO2, which are N-type semiconductors. Thickness of the space-charge-layers increases with annealing time. Such growth of layers results in narrowing the parts of channels through which electrons flow, that is, in enhancing the PTCR.抄録全体を表示PDF形式でダウンロード (3669K) -
海江田 義也, 小黒 信高2002 年 49 巻 7 号 p. 588-592
発行日: 2002/07/15
公開日: 2009/05/22
ジャーナル フリーIt is revealed recently that the familiar chemical compound MgB2 is a superconducting material and the superconducting transition temperature Tc is 39 K It is not easy to produce the good MgB2 by conventional production method. The simple method to produce the MgB2 in a short time is developed by means of a combustion synthesis process with the heat of formation of elements. MgB2 is not able to be produced by a direct combustion synthesis process of Mg and B. Some main reasons are that the heat of formation of MgB2 is small, Mg tends to vaporize, and the Mg powder is very rough but B powder is very fine. On the other hand, MgB2 is able to be produced by the combustion synthesis process of Mg and B using the combustion synthesis of Ti and C proposed in the present paper. The oxidation and the vaporization of Mg are suppressed because the production is done in a very short time in a high vacuum. Moreover, the ratio of Mg and B is stabilized, so that the superconducting properties are assumed to be improved and the production process of MgB2 becomes simple.抄録全体を表示PDF形式でダウンロード (1861K) -
BiO(NO3)-KOH-H2O系西尾 友志, 雨澤 浩史, 堀部 正吉, 山本 直一2002 年 49 巻 7 号 p. 593-599
発行日: 2002/07/15
公開日: 2009/12/04
ジャーナル フリーThe formation diagram of BiO(NO3)-KOH-H2O system was studied using hydrothermal or "wet" method. New seven kinds of compounds of bismuth basic nitrate complex oxides were detected by XRD measurements. The four of new compounds were separated as single phases and the chemical compositions were determined to be Bi5(NO3)2O6(OH), Bi5(NO3)O6(OH)2, Bi6(NO3)3O7(OH) and Bi6(NO3)2O7(OH)2, respectively. The effects of the temperature and pH value on the composition of the compounds were also speculated.抄録全体を表示PDF形式でダウンロード (1776K) -
鈴木 裕之, 洪 慎思, 篠崎 賢二, 黒木 英憲2002 年 49 巻 7 号 p. 600-606
発行日: 2002/07/15
公開日: 2009/12/04
ジャーナル フリーAddition of boron and carbon in sintered steel as a promising substitute for copper was tried in order to promote recycling of used steel from scrapped cars. Atomized iron powders mixed with amorphous boron and/or graphite, or 1.5mass%Cu and 1.0mass%C were pressed into 5 mm cube under 600MPa. Most compacts were heated in vacuum in a differential dilatometer with a rate of 10K/min up to 1430 K, and held for 60 min.
Similar differential dilatometric curves were observed in Fe-0.05mass%B-1.0mass%C and Fe-1.5mass%Cu-1.Omass%C compacts. Their dimensional changes during sintering were similar too, yet the dimensional change of the former material was smaller. In 1.Omass%C compacts, Fe-B-C eutectic liquid did not appear with the boron addition of 0.05 mass%. In high boron compacts of Fe-0.5mass%B-1.Omass%C sintered at 1430 K for 60 min and cooled slowly, iron particles surrounded by the eutectic liquid were remarkably spherodized, and cores and cases of them became pearlite and ferrite, respectively.抄録全体を表示PDF形式でダウンロード (3372K) -
仙名 保2002 年 49 巻 7 号 p. 608
発行日: 2002/07/15
公開日: 2009/05/22
ジャーナル フリーPDF形式でダウンロード (101K) -
北條 純一2002 年 49 巻 7 号 p. 609-614
発行日: 2002/07/15
公開日: 2009/05/22
ジャーナル フリーMany kinds of ceramic composites have been studied to improve the mechanical properties. In order to achieve the excellent properties, it is important to finely and homogeneously disperse the second phase in the matrix. The use of composite particles is a promising approach. The fine composite powders of SiC and Si3N4 systems were prepared by vapor phase reaction methods. The sintering of them produced the nanocomposites. The fine dispersion of h-BN particles was effective to improve the thermal shock resistance of SiC and Si3N4. MoSi2-SiC composite powder was prepared by a carbothermal reduction method. High hardness and fracture toughness were achieved by fine-grained microstructure and dispersion of fine SiC particles in MoSi2. Ni-coated TiC particles were prepared by a chemical plating method. The mechanical properties of the sintered body were improved by the homogeneous distribution of TiC particles in Ni matrix. A12O3 particles were coated with fine Ni powder by an agglomeration coating method, and the porous sintered bodies were produced by sintering. Molten metals (Ni and Cu) easily infiltrated into the porous bodies, giving the homogeneous composites of A12O3-metal systems.抄録全体を表示PDF形式でダウンロード (5652K) -
隅山 兼治, 彭 棟梁, 山室 佐益, 日原 岳彦2002 年 49 巻 7 号 p. 615-619
発行日: 2002/07/15
公開日: 2009/12/04
ジャーナル フリーCluster-assembling is superior in nano-scale-structure control, where we have to make clusters regular in size to draw out the size-dependent characteristics. Using a plasma-gas-condensation type cluster deposition apparatus, we have succeeded in preparing monodispersed transition metal clusters with the mean sizes d=5 to 15nm. We carried out measurement of a transmission electron microscopy and electrical resistivity for clusters randomly deposited on a substrate. The cluster assembling process is interpreted in terms of the percolation theory. The critical percolation thickness, tc, increases with increasing d, while the critical coverage rate estimated from tc is 0.63, being independent of d. tc also increases with increasing the substrate temperature owing to the surface migration of clusters on the substrate. The electrical resistivity and transmission electron microscope image demonstrate the cluster-cluster coalescence above 500K.抄録全体を表示PDF形式でダウンロード (4717K) -
村瀬 琢, 佐々木 智恵子, 梅田 秀信, 榎戸 靖, 野村 武史2002 年 49 巻 7 号 p. 620-625
発行日: 2002/07/15
公開日: 2009/05/22
ジャーナル フリーThe properties of ferrite granules are influenced by the characteristics of their precursors; powders and slurries. The properties of granules have a marked effect on the compaction behaviors and microstructures. The plastic viscosity and Bingham yield point of the slurry mixed with dry-milled powders were higher than that with wet-milled powders. The granules produced by dry-milled powders contained large pores, but the granule density was high. The density of the green body produced by dry-milled powders increases at lower compacting pressures. The sintered body produced by dry-milled powders showed lower density because numerous large defects retained.抄録全体を表示PDF形式でダウンロード (3035K) -
伊東 純一, 朴 大出, 大橋 直樹, 坂口 勲, 八島 勇, 羽田 肇, 田中 順三2002 年 49 巻 7 号 p. 626-632
発行日: 2002/07/15
公開日: 2009/12/04
ジャーナル フリーIn order to improve the understanding of the role of rare-earth dopant in BaTiO3, the effect of microstructure and oxygen defect have been investigated on the electrical properties of polycrystalline La- and Ho-doped BaTiO3. The BaTiO3 doped with Ho 2at.% had the core-shell structure in each grain, while La-doped BaTiO3 did not have the core-shell. The core-shell structure in Ho-doped BaTiO3 consists of a ferroelectric core and a nonferroelectric shell. However, the dielectric properties of Ho-doped BaTiO3 with core-shell structure exhibited no temperature-stability as La-doped BaTiO3. Furthermore, the oxygen diffusion related to dielectric properties was also studied from the viewpoint of defect chemistry. The oxygen diffusion coefficients for BaTiO3 specimens were determined by secondary ion mass spectrometry. The oxygen diffusion coefficient for La-doped BaTiO3 was highly influenced by the amount of La-doping, while that for Ho-doped BaTiO3 was independent of the amounts of Ho-doping.抄録全体を表示PDF形式でダウンロード (1940K) -
兼子 正生, 今村 正人, 全 敏榮, 柳沢 章2002 年 49 巻 7 号 p. 633-637
発行日: 2002/07/15
公開日: 2009/05/22
ジャーナル フリーElectrical resistance characteristics of sintered material made by stainless steel fiber has heat-resistance, and corrosion-resistance, and are therefore often used for polymer filter, automobile exhaust filters, and other filters.
In this study, 20Cr-5Al stainless fibers are.sintered for the first time by the hot water soluble resin coated coilshaving methods and electrical resistance characteristics as sintered material were studied. Though the fiber heatresistance of this stainless steel fibers has been verified, there are almost no studies on the sintering characteristics, purposes, etc. of metal fibers.
The electrical resistance characteristics of fiber sintered materials were investigated for the use in heaters, and the results showed that the specific gravity changes in the sintering, compression of rolling processes, and the specific resistance decreases as the porosity becomes decrease, indicating that the specific resistance of sintered material can be controlled.抄録全体を表示PDF形式でダウンロード (1673K) -
Keijiro Terashita, Takehiko Nishimura, Susumu Natsuyama, Munetake Sato ...2002 年 49 巻 7 号 p. 638-645
発行日: 2002/07/15
公開日: 2009/05/22
ジャーナル フリーA high-shear mixer was used to mix a two-component system different only in the density, which was subjected to DEM (Discrete Element Method) simulation. In the first place, the kinetic motion of particles in an agitating vessel was visualized to obtain the information on how particles different in granular density were mixed and segregated. Then, segregation index was defined to clarify the relationship of segregation index and density ratio with operational conditions. The conditions were also clarified for obtaining favorable mixing conditions while segregation was prevented. In other words, it has been pointed out that DEM simulation could be not only employed to readily understand the mixing and segregation conditions of particles in a mixer but also effective in determining optimal operational conditions for obtaining favorable mixing conditions even when the density ratio is different.抄録全体を表示PDF形式でダウンロード (619K)
- |<
- <
- 1
- >
- >|