巻号一覧
49 巻, 5 号
選択された号の論文の17件中1～17を表示しています
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Toshio Kawahara, Yasuhiro Ohbuchi, Akitsugu Kimura, Yoichi Okamoto, Ju ...2002 年 49 巻 5 号 p. 355-359
発行日: 2002/05/15
公開日: 2009/05/22
ジャーナル フリーPA spectra with several sintering temperatures on the Bi doped and Pr doped ZnO varistors were measured using the gas microphone method and compared, where the grain structure was observed by the laser microscope. The PA signals in the long wavelength excitaion light decreased as the sintering temperature increased, although the PA signals were large at the short wavelength region on the all samples. The PA signal intensity seems not to depend on the surface area caused by the grain structure change, but it might also relate to the quality of the sintered samples such as the deep levels or defects in the grain. The Pr doped samples need the higher sintering temperature to get the high quality samples than the Bi doped samples.抄録全体を表示PDF形式でダウンロード (2337K) -
林 千歳, 篠田 剛, 加藤 喜久2002 年 49 巻 5 号 p. 360-366
発行日: 2002/05/15
公開日: 2009/05/22
ジャーナル フリーDirected Plasma Fabrication (DPF) is a rapid tooling process that is based on controlled deposition of molten powder particles according to computer-controlled patterns. It makes fully dense, near net shape metal components without molds or dies, and without forming, pressing or forging systems.
Experimental works were carried out using conventional low current Plasma Transferred Arc Welding system, and metallic powder was stellite #21. Cylindrical shapes are successfully deposited as dimensions with 2.5-4.2 mm wall thickness.
As compared to thermal conductivity, there is considerable effect of some physical factors like arc force on the penetration depth of the molten pool, during DPF process. And, if the arc length is appropriately controlled, cross sectional area of molten pool and its penetration depth can be roughly approximated to the heat source assumed to be moving point type.抄録全体を表示PDF形式でダウンロード (3227K) -
Ritsuko Tsuzuki, Yasuhiro Saiki, Sho Kataoka, Eiji Yuasa2002 年 49 巻 5 号 p. 367-371
発行日: 2002/05/15
公開日: 2009/05/22
ジャーナル フリーIt was already reported that Al-Ni-Zr amorphous alloys powder was expected to show excellent properties in not only mechanical such as toughness and strength but also abrasion and corrosion resistance. It is also known that those alloys can be produced by Double Mechanical Alloying (DMA) method, which has taken instead of the rapid solidification method. In this study, compacts of Al-Ni-Zr amorphous were formed from amorphous powder mechanically alloyed, by Vacuum Hot Press (VHP) method for various conditions. Densities of compacts were measured and the rupture strength and the deflection were tested in order to know its mechanical properties. As a result, a relative density of the compact increases as compacting pressure increases and it becomes constant until 700-800 MPa, then the particle begins to deform over that pressure range. In this compacting pressure range, for the density is stable, the both of the rupture strength and the maximum deflection become to the maximum value. Below that pressure, consolidation is not packed enough, and above that pressure, the crack inside compact occurs due to over pressure. Therefore, that range of pressure can be thought optimum compacting pressure to form Al-Ni-Zr amorphous consolidation.抄録全体を表示PDF形式でダウンロード (5207K) -
佐藤 泰史, 吉岡 恒太郎, Petrykin Valery, 垣花 眞人, 田中 仁人, 山口 愛, 勝又 隆玄, 安岡 宏2002 年 49 巻 5 号 p. 372-376
発行日: 2002/05/15
公開日: 2009/12/04
ジャーナル フリーPolycrystalline samples of (CaxLa1-x)(Ba1.75-xLa0.25+x)Cu3O7+δ(CLBCO) tetragonal superconductor for x from 0.0 to 0.6 were studied by Raman scattering technique, which is sensitive to oxygen site symmetry in the high-Tc superconductors. On the Raman spectra, five extra modes at 200, 320, 400, 565 and 610 cm-1, which did not appear on Raman spectra of tetragonal YBa2Cu3O6, were observed. Based on the model that apical oxygen O(4) is displaced by La3+ on Ba site and the result of group theoretical analysis for this model, the 565 cm-1 mode which possessed the strongest intensity among these extra modes could be assigned to another O(4) vibration. This indicates that O(4) is strongly attracted by La3+ on Ba site, resulting in a change of local structure.抄録全体を表示PDF形式でダウンロード (408K) -
吉田 裕史, 齊藤 高志, 山田 高広, 東 正樹, 高野 幹夫2002 年 49 巻 5 号 p. 377-381
発行日: 2002/05/15
公開日: 2009/05/22
ジャーナル フリーPressure induced phase transitions were found in spin ladder compounds SrCu2O3 and Sr2Cu3O5 by powder X-ray diffraction (XRD) experiment with diamond anvil cell (DAC) and synchrotron radiation. The structure of the HP phase of SrCu2O3 was successfully solved by Rietvelt analysis. In the orthorhombic structure (space group Pmmn) with unit-cell parameters of a=10.628Å, b=3.885Å and c=3.282Å, the Cu2O3 planes at SrCu2O3 became "fluttering" as that of CaCu2O3. Application of an external pressure induced a structural transition as a substitution of smaller cation (Ca for Sr) did.抄録全体を表示PDF形式でダウンロード (395K) -
Yuanbin Xu, Hiroyuki Nomura2002 年 49 巻 5 号 p. 382-389
発行日: 2002/05/15
公開日: 2009/05/22
ジャーナル フリーCorrosion behavior plays a decisive role for biocompatibility of titanium alloy implants. In this study, Ti-5Al-2.5Fe alloy samples were formed through metal powder injection molding (MIM) process and their potentiodynamic tests were carried out in a phosphate buffered solution with and without HCl. Experimental results showed that the slope of current potential curves increased within the passive region. In comparison to results of samples processed by vacuum arc melting followed by annealing, existence of micro pores was considered to be a main factor for observed corrosion behavior of MIM processed sample. The observations were further discussed in detail based upon a model of electrochemical reaction system and quantitative equations for quasi-passive state.抄録全体を表示PDF形式でダウンロード (3811K) -
河本 邦仁2002 年 49 巻 5 号 p. 392
発行日: 2002/05/15
公開日: 2009/05/22
ジャーナル フリーPDF形式でダウンロード (73K) -
舟橋 良次, 生田 博志, 鹿野 昌弘, 松原 一郎, 水谷 宇一郎2002 年 49 巻 5 号 p. 393-399
発行日: 2002/05/15
公開日: 2009/05/22
ジャーナル フリーThree kinds of single crystalline whiskers of Bi2Sr2CoO6 (BC-221), (Bi2Sr2O4)x(CoO2)2 (BC-222), and (Ca2CoO3)xCoO2 (Co-225) phases were grown from surfaces of precursor plates by annealing in an O2 gas flow. The phases of the whiskers can be controlled by the Co content of the precursor plates Average compositions of the whiskers are Bi2.5(Sr, Ca)3.3CoO6+δ, Bi3.0(Sr, Ca)3.1Co2.0O9+δ, and (Ca, Sr, Bi)1.9Co2.0O5+δ for the BC-221, the BC-222, and the Co-225 whiskers, respectively. Although the Co-225 whiskers are 1.2mm at the longest, the BC-221 and the BC-222 whiskers reach lengths of as much as 10mm. Because the growth points of the whiskers are their bases, the length of the whiskers depends on the microstructure of the precursor plates. Both BC-222 and Co-225 whiskers show excellent thermoelectric properties at high temperature even in air.抄録全体を表示PDF形式でダウンロード (6653K) -
藤田 顕二郎, 中村 和郎2002 年 49 巻 5 号 p. 400-405
発行日: 2002/05/15
公開日: 2009/12/04
ジャーナル フリーNaxCoO2 single crystal has an anisotropy in thermoelectric properties, in which in-plane thermoelectric performance shows an excellent dimensionless value of ZT (Z=S2⋅m-1k-1T). The high thermoelectric performance of a polycrystalline NaxCoO2, however, is not yet realizable because of its high electrical resistivity. Therefore, the highly oriented NaxCoO2 polycrystals were synthesized and their thermoelectric properties were measured. For making the highly oriented NaxCoO2, the single crystals were used as starting materials with three kinds of powders; for (a) mixed Na2CO3 and Co3O4, (b) ground NaxCoO2 polycrystal and (c) Na2CO3. Consequently, it was succeeded in the preparation of the highly oriented sample in each case. The electrical resistivity of the oriented NaxCoO2 ceramics prepared by the (a) powder was about 6.6-8.9 mΩcm. The electrical resistivity of the ceramics, which was prepared by the (b) powder, decreased to 2.5-3.9 mΩcm. The electrical resistivity of the ceramics synthesized by the (c) powder was about 2 mΩcm. The difference of their electrical resistivities was due to the effects of the orientation, the grain boundary resistivity and the content of Na. The maximum power factor was about 500μW/mK2 at 663 K.抄録全体を表示PDF形式でダウンロード (6937K) -
Mikio Ito, Tomoya Nagira, Yoshitsugu Tsuchiya, Shigeru Katsuyama, Kazu ...2002 年 49 巻 5 号 p. 406-411
発行日: 2002/05/15
公開日: 2009/05/22
ジャーナル フリーThe synthesis of the NaxCo2O4 thermoelectric oxide was tried by mechanical grinding (MG) and spark plasma sintering (SPS). The effects of the synthesis process on its microstructure and thermoelectric properties were investigated. The sample prepared by MG for 72 ks and SPS under 40 MPa at 773 K for 0.9 ks in air was composed of the Co3O4 and CoO phases, and NaxCo2O4 phase formation did not occur. In the case that the MG powder was calcined at 1183 K for 3.6ks in air and then subjected to SPS at 1073 K in vacuum, the sample was mostly composed of the NaxCo2O4 phase with several Co oxides. These Co oxides remained present even after subsequent annealing at 1083 K for 72 ks in air. On the other hand, in the case of SPS at 773 K for 0.9 ks in air and subsequent annealing, the sample was composed of the NaxCo2O4 phase without any other impurity phases. Besides that, a significant fine microstructure as compared to that of the pressurelessly sintered sample, could be obtained for this sample. However, the thermal conductivity of the sample was higher than that of the sample prepared by the conventional solid state reaction, i.e., calcination and subsequent pressureless sintering. This is considered to be associated with a degree of the crystallographic orientation of the compacts.抄録全体を表示PDF形式でダウンロード (3903K) -
日下部 竜太, 山口 晃生, 小林 慶三, 松本 章宏2002 年 49 巻 5 号 p. 412-416
発行日: 2002/05/15
公開日: 2009/05/22
ジャーナル フリーA p-type thermoelectric film of (Bi2Te3)0.25(Sb2Te3)0.75 was fabricated by radio frequency sputtering. The target for the sputtering was prepared by mechanical alloying (MA) and pulsed current sintering (PCS) process. The single phase of Bi0.5Sb1.5Te3 was obtained by planetary ball milling Bi powder, Te powder and Sb powder for 36ks. The obtained powder was consolidated by PCS into the cylindrical target of 50 mm in diameter and 4mm in thickness at 643 K under a pressure of 13 MPa. The sintered body consisted of Bi0.5Sb1.5Te3 without cracks. The sintered Bi0.5Sb1.5Te3 was joined to Cu backing plate with In for an insertion by PCS process. The thin film of (Bi2Te3)0.25(Sb2Te3)0.75 was fabricated on a polyimide substrate by RF sputtering. The thickness of this thin film was about 15-20μm. This film was amorphous state and crystallized at about 520 K. The performance of this p-type thermoelectric film after the crystallization were 2.0mV in voltage and 2.9μA in current at 20 K of the difference between heating side temperature 353 K and cooling side temperature 333 K.抄録全体を表示PDF形式でダウンロード (3120K) -
藤木 章2002 年 49 巻 5 号 p. 418
発行日: 2002/05/15
公開日: 2009/05/22
ジャーナル フリーPDF形式でダウンロード (74K) -
山本 将史, 深澤 恒典, 山末 英嗣, 石原 慶一2002 年 49 巻 5 号 p. 419-425
発行日: 2002/05/15
公開日: 2009/05/22
ジャーナル フリーThe fuel economies for various kinds of automobiles have been investigated. According to the fuel economy based upon the department of transportation standard, the fuel economies in 2000 improved 9-23% compared to those in 1990 for each class of the curb weight. However, the total fuel economy in Japan, which were estimated from the both data of the total amount of fuel consumption and total killometrage in Japan from 1965 to 2000, show about 9 km/liter, and in the recent decade it became rather worse. The reason for this inconsistency is that the large size automobile became popular because of the inclination of user, anti-regulation of automobile tax, price down of fuel and so on. In order to improve the total fuel economy aiming the reduction of CO2 emission, two problems, which are "improvement of the fuel economy for the respective automobile" and "suppression of the over sizing of automobile", are examined.抄録全体を表示PDF形式でダウンロード (578K) -
鈴木 正実2002 年 49 巻 5 号 p. 426-429
発行日: 2002/05/15
公開日: 2009/05/22
ジャーナル フリーAutomotive industry is devoting a vast amount of R&D resources to addressing environmental issues, such as global and conservation. Consequently, automotive materials and parts are required to "Green". Powder metallurgy (PM) has the advantage of potentially being environmentally friendly by being able to tackling the above issues. Therefore, future expansion in PM usage for automotive applications is expected. In this paper, key issues for expansion of PM usage are discussed. These issues include: 1) designers misperception of PM's advantages, 2) increase in technical difficulty. In addition, the following recommendations are provided: a) expanding cooperation between supplies and OEMs, b) strengthening problem solving capabilities, and c) educating system design engineers.抄録全体を表示PDF形式でダウンロード (6443K) -
草加 勝司, 伊藤 孝至, 鰐部 吉基2002 年 49 巻 5 号 p. 430-437
発行日: 2002/05/15
公開日: 2009/05/22
ジャーナル フリーThe objective of this study is to elucidate the relation between magnetic properties and residual pores in various PM magnetic alloys typical of car parts, mainly from authors'experimental results. In practice, magnetic properties was discussed and evaluated from the three points of view: porosity and pore size/shape control, acceptable limit of residual pore for practical use, and pore reduction by sintering technique.
The results obtained were summarized as follows:
(1) Soft magnetic properties were more or less affected by pore morphologies (size/shape) as well as porosity and consequently, expressed with linear equation of these parameters, based on the size-shape dispersion diagram.
(2) Pore dependence of magnetic degradation caused by material defects (faults), deformation, heat-treatment, corrosion attack etc. was quantitatively evaluated together with magnetically-restoring methods.
(3) Several approaches to poreless magnetic alloys were tried by means of pertinent sintering technique such as powder refining-, liquid phase-, spark plasma-sintering and further, micro/macroscopic composite ones are expected as being characteristic of powder metallurgy.抄録全体を表示PDF形式でダウンロード (6267K) -
藤木 章, 前川 幸広, 馬渕 豊, 渡部 貴也, 菅谷 好美, 岩切 誠, 芝野 隆2002 年 49 巻 5 号 p. 438-443
発行日: 2002/05/15
公開日: 2009/05/22
ジャーナル フリーThe authors have previously reported on the warm compacted and normal temperature (1140°C) sintered P/M sprockets of the roller chain system of non-DIG (normal MPI gasoline) engines. In this new development, the mechanical properties of several warm-compacted and high-temperature sintered P/M steels were investigated. A wear test was also conducted to examine the anti-wear characteristics of these material using dummy engines. Finally, sprockets of silent chain system of DIG engines were developed that can endure sever wear conditions. The base powder used was a hybrid material (Distaloy DC1). It was 2mass% Ni (nickel) and was diffusion bonded to pre-alloy Fe-1.5mass%Mo (molybdenum) powder. The warm compaction was conducted with the powder, die and tools at 130°C. The sintering temperature was 1190°C and heat treatment was also applied to the sprockets.抄録全体を表示PDF形式でダウンロード (5201K) -
菅野 光輝, 武田 義信, Lindqvist Björn2002 年 49 巻 5 号 p. 444-449
発行日: 2002/05/15
公開日: 2009/05/22
ジャーナル フリーThe dominating part of mass produced PM-steels today are sintered in continuous furnaces operating at maximum 1150°C. The alloying elements Cu, Ni, Mo and C are normally used to obtain good material properties. However, environmental concerns and cost might restrict the use of especially Cu and Ni, as additives to PM-steels, in the future. Since many years, Cr-alloyed PM-steels are available as complement to the existing Cu/Ni-alloyed materials. This family of materials has many advantages and the most important are cost, the ability to be recycled and hardened. However, still PM part production of Cr-steels is mainly limited to top performance applications sintered at high temperature. In the present paper focus is put on processing Cr-alloyed PM-steels in furnaces operating at maximum 1150°C. It shows necessary precautions to betaken for the successful sintering of PM-steels alloyed with Cr.抄録全体を表示PDF形式でダウンロード (3973K)
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