巻号一覧
50 巻, 11 号
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Toshihiko Shigematsu2003 年 50 巻 11 号 p. 810
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーPDF形式でダウンロード (48K) -
Ruoxin Du, Hiroshi Okamura, Ryuzo Watanabe2003 年 50 巻 11 号 p. 811-815
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーHigh energy ball milling technique is often used in synthesizing ceramic composites. In this study, in order to obtain ultrafine TiN-AlN composite powder, which can be expected to improve the sinterability, mechanical alloying was employed, using AlN, Ti powders and ammonium carbonate as starting materials. The presence of nano-sized TiN was verified by XRD and TEM.抄録全体を表示PDF形式でダウンロード (4366K) -
Hoon Chul Yang, Jong Kwang Kim, Ki Tae Kim2003 年 50 巻 11 号 p. 816-820
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーA finite element analysis for near-net-shape forming of aluminum alloy powder was performed under warm rub-ber isostatic pressing and warm die pressing. The advantages of warm compaction by rubber isostatic pressing were discussed to obtain a part with better density distributions. The shape of rubber mold was designed by determining a cavity shape that provides a desired shape of the final powder compact. To simulate densification and deformed shape of a powder compact during warm pressing, the elastoplastic constitutive equation based on yield function of Shima-Oyane was implemented into a finite element program (ABAQUS). The hyperelastic constitutive equation based on the Ogden strain energy potential was employed to analyze nonlinear elastic response of rubber. Finite element results were compared with experimental data for aluminum alloy powder compacts under warm die pressing and warm isostatic pressing.抄録全体を表示PDF形式でダウンロード (379K) -
Takeshi Yamashita, Ryuzo Watanabe2003 年 50 巻 11 号 p. 821-827
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーWhen the carbon content in the Fe phase of liquid-phase-sintered Fe-Cu alloy is graded by using solid carburization method, the microstructure of the sample has a characteristic orientated Fe and Cu phases. This microstructural orientation towards the direction of carburization and the distributed area of the oriented Fe phase depends on the diffusion distance and the carbon content. In this paper, we executed three simulation programs by using Multi-Layered Potts Model and Monte Carlo method. From the simulation result, the orientated Cu phase was observed among coalescent Fe-C particles, and also sharp dihedral angles of Fe-C particles were observed. So, these combined simulations could succeed to reproduce the microstructure characteristics of orientated Cu phase of liquid-phase-sintered Fe-Cu alloy.抄録全体を表示PDF形式でダウンロード (2418K) -
Tao Lin, Liying Zhang, Zhimeng Guo, Wenxia Li, Chengyi Wu, Qinghua Wu2003 年 50 巻 11 号 p. 828-831
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーBy means of the mercurial barometer and pore size analyzer, the effects of bridged particles on the pore volume distribution in nano-scaled cemented carbide powder and its compact were investigated. Also the apparent density, specific surface area and green density were studied before and after sedimentation separating and shear milling by BET specific surface area analyzer and SEM. The results show that there is more than one peak on pore volume distribution pattern because of the presence of bridged particles. The apparent density and green density can be greatly improved by shear milling.抄録全体を表示PDF形式でダウンロード (1840K) -
Tianjun Liu, Jeff Danaher, Linda Tremblay, Ray Guo2003 年 50 巻 11 号 p. 832-836
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーThe advantages of green machining have been well recognized, including longer cutting tool life and the ability to make complex parts with sinter-hardenable powders. The high green strength of the compacted parts also prevents green cracks and damages from handling. But, green machining is yet to be widely used since the required high green strength (in excess of about 20 MPa) cannot be readily obtained through conventional P/M techniques.
The limitation of using green machining is being removed with a newly developed high green strength (HGS) polymeric lubricant at QMP. One distinguished characteristic of this lubricant is its response to temperature. High green strength can be obtained at a compacting temperature of 55°C, which can be easily reached throughout a green part by cold compaction. Even a higher green strength up to -48MPa can be reached by a subsequent curing process for parts pressed to density of 6.8 g/cm3. This high green strength has made green machining possible for those parts fabricated through conventional P/M processes.
This paper presents the results of green machining tests performed on several timing sprockets. The material used was a sinter-hardenable powder mix of QMP ATOMET 4601 and the HGS lubricant. The sprockets were pressed to a density of -6.8g/cm3 by cold compaction. Green machining (turning a groove along the middle of the teeth) was performed on as-compacted and cured parts. Results showed that the HGS lubricant provided sufficient green strength for clamping and machining operations, especially after curing. The machined surfaces appeared to be smooth and the edges remained integrated. The green-machined sprockets made of sinter-hardenable powder eliminated heat treatment, providing much longer tool life and improved size tolerances.抄録全体を表示PDF形式でダウンロード (7866K) -
Zhu Chunguang, Cao Hongbin, Bao Wenhai2003 年 50 巻 11 号 p. 837-839
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーThe planetary gear seat is a key part of electric winch, a self-help equipment, in cross-country vehicle. It features a complicated form, high running load, and definitely reliable operation. It is difficult to make the part by machining. We find P/M technology is a fairly better way but never easy one, because the structure of two steps internal involute gears is very special and height of the part is comparatively high. In this paper we will introduce you how to manufacture this part by P/M technology in our company.抄録全体を表示PDF形式でダウンロード (234K) -
Tetsuji Saito2003 年 50 巻 11 号 p. 840-843
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーCo-B powders were prepared by chemical reduction. The powders had a spherical shape with an average diameter of about 0.1μm. X-ray diffraction and differential scanning calorimetry studies confirmed that the powders were amorphous. The amorphous powders showed lower saturation magnetization than the crystalline counterparts. Heat treatment of the powders above the crystallization temperature resulted in the formation of fcc Co, hcp Co, Co2B, and Co3B phases. The saturation magnetization of the annealed powders monotonically increased as the annealing temperature increased. On the other hand, the coercivity of the annealed powders rapidly increased with increasing annealing temperature. The powders annealed at 500°C had a saturation magnetization of 92 emu/g with a high coercivity of 1670 Oe.抄録全体を表示PDF形式でダウンロード (1885K) -
Koji Shimojima, Hiroyuki Hosokawa, Mamoru Mabuchi, Masaru Kawakami, Sy ...2003 年 50 巻 11 号 p. 844-847
発行日: 2003/11/15
公開日: 2010/07/12
ジャーナル フリーBinder-free WC was fabricated at the sintering temperature of 1873 K-2023 K by pulsed current sintering (PCS) process, and the density, grain size, hardness and toughness of them were investigated. As a result, the WC sintered at 1973 K showed a very high hardness more than HV10 2700 because it was almost fully dense and no singnificant grain growth occurred during sintering process.抄録全体を表示PDF形式でダウンロード (3979K) -
Yasuo Yamada, Cui'e Wen, Mamoru Mabuchi2003 年 50 巻 11 号 p. 848-850
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーThe present paper describes processing of a lotus-structured porous Ti-Al/Ti composite by SHS with Ti powder and Al rods. Ti-Al intermetallic compound was formed in a range of 200-300μm around the pore by SHS of reaction between Ti and Al, resulting in formation of a lotus-structured porous Ti-Al/Ti composite.抄録全体を表示PDF形式でダウンロード (3069K) -
Dong Ryoul Lee, Wan Jae Lee2003 年 50 巻 11 号 p. 851-855
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーBoride cermets, especially transition metal boride base ones, are promising candidates for wear resistant applications. This study focuses on the criteria for the fabrication of W2NiB2-Ni boride cermets using W, Ni and B elemental powders. Their sintering behaviors and characteristics were examined in relation with compositions and sintering temperatures. The W2NiB2 boride particles were formed by the diffusion and reaction during sintering. It seems to be a easy way to develop the boride cermets such as W2NiB2-Ni cermets.抄録全体を表示PDF形式でダウンロード (5005K) -
Compaction and Sintering of High Speed SteelHiroyuki Y. Suzuki, Masato Fukuda, Hidenori Kuroki2003 年 50 巻 11 号 p. 856-864
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーFine (4μm) and coarse (30μm) water atomized high speed steel powders were prepared as slips and compacted by high-speed centrifugal compaction process (HCP).
The HCP green compacts of the both fine and coarse powders can be sintered to almost full density at 1448K to 1498K without any pressure assistance during sintering. Their sintering behavior, however, were quite different. While the compact of coarse powder needed to form a liquid phase to densify and resulted in a coarse microstructure, that of fine powders densified in solid phase so that fine microstructures were obtained. A homogeneous packing of fine several micron powder by the HCP was essential to solid state sintering of high speed steel. The HCP compact of fine powders showed a comparable hardness and strength to wrought materials.抄録全体を表示PDF形式でダウンロード (7148K) -
Hiroshi Yamamoto, Taichi Mori2003 年 50 巻 11 号 p. 865-869
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーExperiments were carried out to investigate the effect of composition, heat-treatment and nitrogenation conditions on the magnetic properties of Sm-Fe-Co-Ti-N compounds with TbCu7-type structure. The optimum preparation conditions of the compounds were as follows: composition: {Sm10(Fe0.95CO0.05)89.7Ti0.3}82.0N18.0, roller velocity: 50 m/s, heat treatment: 680°C for 60min in high-purity Ar gas, and nitrogenation condition: 420°C for 15h in high-purity N2 gas. Typical magnetic properties of the obtained compound powders were as follows: Jr=0.99 T, Hcj=736.5 kA/m, HcB=540.4 kA/m, (BH)max=140.9 kJ/m3 (17.7 MGOe), and Tc=488°C. It was found that this sample was an exchange spring magnet from recoil loops of the hysteresis curve, TEM photographs and X-ray analysis. The value of (BH)max for the compression-molding isotropic bonded magnet prepared by using from {Sm10(Fe0.95Co0.05)89.7Ti0.3}82.0N18.0 powder was 103.2 kJ/m3 (13.0 MGOe), when the density of bonded magnet was 6.04 Mg/m3. And the average reversible temperature coefficient of Jr was a(Jr)ave.=-0.04%/°C, the temperature coefficient of Hcj in the range from 25°C to 125°C obtained by a linear extrapolation was a (HcJ) =-0.44 %/°C.抄録全体を表示PDF形式でダウンロード (1713K) -
Hiroshi Yamamoto, Hiroaki Nishio, Natsuki Wakamura2003 年 50 巻 11 号 p. 870-874
発行日: 2003/11/15
公開日: 2009/12/04
ジャーナル フリーThis experiment was carried out to investigate the effect of ZnO substitution on the magnetic and physical properties of Co-Ni ferrite fine particle prepared by the chemical coprecipitation method without post-annealing process. The chemical coprecipitation compositions were chosen according to the formula (CoO)0.5(NiO)0.5-x(ZnO)x⋅n/2(Fe2O3), where x was varied between 0 and 0.5, and n between 2.0 and 3.0. The saturation magnetization σs, has a tendency to increase up to x=0.3, however decrease when x is above 0.3. On the other hand, the coercivity HcJ decreases as x increases. Optimum magnetic properties were achieved with materials of composition (CoO)0.05(NiO)0.45(ZnO)0.05⋅1.25(Fe2O3). The typical magnetic and physical properties are saturation magnetization σs=61.9×10-6 Wb⋅m/kg (49.3 emu/g), coercivity HcJ=372.5kA/m (4.68 kOe), the lattice constant a= 0.8379 run, and the average particle size = 38 nm. The rotational hysteresis integral Rh, which is related to the magnetization mechanism of these fine particles, is 1.80, and it is found that the magnetization mechanism is an incoherent rotation mode. Crystalline magnetic anisotropy constants are K11=+6.7×104 J/m3 (+6.7×105 erg /cm3) and K2=-16.8×104J/m3 (-16.8×105 erg/cm3).抄録全体を表示PDF形式でダウンロード (1759K) -
Wei Zhang, Hiroto Ohta, Kazuyoshi Yoshimura, N. V. Mushnikov, Tsuneaki ...2003 年 50 巻 11 号 p. 875-879
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーWe report experimental results of magnetic susceptibility and the high-field magnetization of Yb1-xYxInCu4 under various fixed temperatures, most of which are found to be explained by the calculation according to the modified Falicov-Kiwball model, although the observed sharp transition in substituted YbInCu4 is unexpected by this model. By proper scaling of the (Hv Tv) data extracted from the high-field magnetization measurements, we can collect all of the data from the system of Yb1-xYxInCu4 onto a universal H-T phase diagram, but it is shifted from the relationship expected by Falicov-Kimball model.抄録全体を表示PDF形式でダウンロード (379K) -
Yoshihiro Takitani, Toshirou Matuki, Jin-Feng Li, Ryuzou Watanabe2003 年 50 巻 11 号 p. 880-884
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーThe synthesis of Ti3SiC2 powder by mechanical alloying (MA) from elemental Ti, Si and C powders and evaluation of some properties of the sintered compacts of the MA powder were conducted. MA was carried out by vibratory ball milling and planetary ball milling. The influence of parameters, such as running time, ball size and rotation speed on MA powder were examined. The annealing of the MA powder was done at various temperatures and holding times. The MA powders could be sintered to dense Ti3SiC2-based ceramics which contained TiC as a secondary phase. Mechanical, thermal and electrical properties of sintered compacts were evaluated. The Ti3SiC2-based compact showed low hardness, high Young's modulus, and plastic behavior at high temperatures over 1373 K, And the compact showed high thermal expansion, high thermal conductivity, and higher electrical conductivity than other conventional ceramics.抄録全体を表示PDF形式でダウンロード (4876K) -
Takashi Ishikawa, Atsushi Kawamoto, Kenji Ohmori2003 年 50 巻 11 号 p. 885-888
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーA reduction and diffusion method (R/D) is used to make a mother alloy of Sm-Fe-N anisotropic magnets. Reduction of 0.5 wt% of samarium content compared to conventional powder increases magnetization. Milling and surface treatment improve the squareness of demagnetization curve, the aging property and the heat resistance quality. Maximum energy product of 292 kJ/m3 is obtained with the powder. High coercive force is maintainable even if the powder is exposed for 300 h in 80°C and 90 %RH. The maximum energy product of 141 kJ/m3 is obtained with an injection molded anisotropic magnet. The aging property estimated by irreversible flux loss is comparable to the conventional MQP-B magnets. The heat resistance temperature (T-5%) at which the initial irreversible flux loss becomes -5% is 125-more than 150°C for Sm-Fe-N magnets and 150-170°C for hybrid magnets.抄録全体を表示PDF形式でダウンロード (312K) -
Taesuk Jang, Dae-Hoon Lee, Tae-Whan Lim, C.J. Choi, B.K. Kim2003 年 50 巻 11 号 p. 889-893
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーFabrication of Nd-Fe-B magnetic powders by R-D process using spray-dried precursors was tried. Due to stable formation of a-Fe as a primary phase as same as that in ingots, the hard magnetic Nd2Fe14B phase was not formed in the alloy powder with the composition of stoichiometric Nd2Fe14B unless excessive amount of Nd precursor or Ca was added in the process. However, this excessive addition, especially for Ca, led to abnormal grain growth of Nd2Fe14B. On the contrary, Nd2Fe14B was successfully obtained as a major phase from the alloy powder with the composition of Nd15Fe77B8 without such excessive addition. The size of spherical shape Nd2Fe14B particles mostly consisted of one or more subgrains was less than 1, um. The coercivity measured from this powder was relatively low (-3 kOe) mostly due to residual CaO and soft magnetic phases.抄録全体を表示PDF形式でダウンロード (1995K) -
Yuichi Ogawa, Hisato Tokoro, Shigeho Tanigawa2003 年 50 巻 11 号 p. 894-898
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーProduction of R-Fe-B type permanent magnets has been rapidly increased since its discovery in 1983. This type of permanent magnets is used various applications today. The application for electric motors is one of the expanding field of R-Fe-B magnets in future. We studied the improvement of particular characteristics of R-Fe-B magnets required in motor applicant. In this paper, improvement of high temperature stability, mechanical strength and magnetizability will be reported. By refinement of microstructure, R-Fe-B sintered magnets with high temperature stability comparable to Sm-Co type sintered magnets was obtained. This material also showed high mechanical strength because of its fine microstructure.抄録全体を表示PDF形式でダウンロード (1633K) -
Xuanhui Qu, Jianxiang Gao, Mingli Qin, Changming Lei2003 年 50 巻 11 号 p. 899-902
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーAn improved wax-based binder was developed for powder injection molding of WC-TiC-Co cemented carbides. The critical powder loading and the flow behavior of the feedstock were determined. I was found that the critical powder loading could achieve up to 62.5 Vol% and the feedstock exhibited a pseudo-plastic flow behavior. The injection molding, debinding and sintering processes were studied. The dimension deviation of the sintered samples could be controlled in the range of ±0.2% with the optimized processing parameters and the mechanical properties were equivalent to those of the same alloy made by conventional press-sintering process.抄録全体を表示PDF形式でダウンロード (4814K) -
Hideki Kyogoku, Shinichiro Komatsu, Masahiro Shinzawa, Takashi Matsuok ...2003 年 50 巻 11 号 p. 903-907
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーThe purpose of this study is to investigate the influence of powder characteristics on the mechanical properties, especially fatigue and impact strengths, of the austenitic stainless steel compacts made by powder injection molding. The specimens were made of water-atomized (WA) and gas-atomized powders which were blended with a polyamide binder system. The compacts were debound in air and then sintered in vacuum at various temperatures for various times. The powder characteristics influenced significantly on the density, microstructure and mechanical properties of the sintered compacts. The fatigue limits of the WA and GA powder compacts were approximately 300MPa and 310 MPa, respectively. The fatigue strength of these compacts was slightly lower than that of the wrought material. The impact value of the sintered compacts increased lineally with increasing density.抄録全体を表示PDF形式でダウンロード (6637K) -
Takahiko Sakaue, Katsuhiko Yoshimaru2003 年 50 巻 11 号 p. 908-911
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーConventional copper powder used to form terminations of MLCC generally contains large flakes with high aspect ratios and large agglomerate spherical particles. The use of agglomerate powder and large flakes results in low dry film density, and thus a thicker film. In our research, we focused on highly dispersed, uniform, and fine flakes and powder that did not contain coarse particles, and examined the paste characteristics and their effect on firing conditions. We found that a smaller particle size would increase the thixotropic value and result in an earlier start to firing. We also discovered that the agglomerate condition of powder had a significant influence on the rheology of the paste. A higher degree of agglomeration would result in higher viscosity and a higher thixotropic value, but would not have a major effect on the firing condition.抄録全体を表示PDF形式でダウンロード (4574K) -
Liying Zhang, Yuxin Tan, Tao Lin, Zhimeng Guo, Chengyi Wu, Qinghua Wu2003 年 50 巻 11 号 p. 912-915
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーThe characteristics of shrinkage kinetics curve of compacts of W-(Ni-Fe)10% with particle size less than 200 nm sintered in hydrogen atmosphere was researched by high temperature dilatometer. And the influence of the particle size of W and green density on commence shrinkage temperature, sharp shrinkage temperature and shrinkage rate were also investigated. It shows that the commence shrinkage temperature and sharp shrinkage temperature of the compact with ultrafine grain are 970°C and 1240°C respectively. The maximum shrinkage rate is 0.11%/°C. The shrinkage ratio decreases with the increase of green density and increases with the increase of sintering temperature.抄録全体を表示PDF形式でダウンロード (272K) -
Takashi Yoshioka, Yukio Makino, Shoji Miyake2003 年 50 巻 11 号 p. 916-920
発行日: 2003/11/15
公開日: 2009/12/04
ジャーナル フリーThe relationship between thermal conductivity and intergranular oxide phase variation in AlN sintered by millimeter-wave heating was investigated. The thermal conductivity was increased with the decrease of a ratio of Al2O3 to Yb203+Al2O3 in the intergranular phase. When a high thermal conductivity of 210 W/(m⋅K) was obtained at 1973 K for 3 hrs under a mixed gas atmosphere of N2 with 3 vol% H2, Yb2O3 phase was observed as an intergranular phase, unlike conventional sintering.抄録全体を表示PDF形式でダウンロード (2264K) -
Koki Kanno, Yoshinobu Takeda, Ricardo Canto Leyton2003 年 50 巻 11 号 p. 921-926
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーAt present, most stainless steel materials are sintered at high temperatures to achieve the desired mechanical, corrosion and high-temperature properties through densification. Although this method of processing achieves the desired properties, the resulting dimensional change can be difficult to control. A potential alternative to reduce the amount of densification required would be stainless steel powders with higher compressibility, which can reach higher green densities at reasonable compaction pressures. The purpose of this paper will be to compare different techniques to attain the desired sintered properties. The mechanical properties and green and sintered densities reached with these techniques will also be discussed.抄録全体を表示PDF形式でダウンロード (2072K) -
Takahiro Inoue, Isao Shimazoe, Izumi Sato2003 年 50 巻 11 号 p. 927-930
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーThe machining of green compacts can lead to manufacturing cost reductions through longer tool life, equipment downsizing, decreased processing times etc. Cost benefits can be gained in particular with materials that are hard to cut, such as sinter hardening materials. We have succeeded in changing product processes for sintered parts with drilled holes, by optimizing processing conditions and tools for improvements in cut surface finish and dimensional accuracy.抄録全体を表示PDF形式でダウンロード (4564K) -
Jun-ichi Yamamoto, Yasuo Shimizu, Hajime Ohtani, Keisuke Shiozaki, Kaz ...2003 年 50 巻 11 号 p. 931-936
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーP-type and n-type β-FeSi2 was produced by utilizing the process of mechanical alloying(MA)and spark plasma sintering(SPS)technique. Raw powders of pure iron, silicon, manganese and cobalt were mixed and mechanically alloyed for 72ks using planetary ball mill. The mixing fractions of the powders were in accordance with the mole fractions of the Fe0.92Mn0.08Si2 (p-type) and Fe0.98Co0.02Si2 (n-type), respectively. The SPS temperature for producing p-type β-FeSi2 was 1073-1153 K and n-type β-FeSi2 was 1073-1173 K, and the holding time was 0.3ks. When the sintering temperature was over these temperatures, α-FeSi2 was produced and thermoelectric properties were reduced. The density of p-type β-FeSi2 sintered at 1153 K was 4.64g/cm3(the relative density was 94.1%), and the maximum power factor was 0.30mW/mK2 at 850 K. The density of n-type β-FeSi2 sintered at 1173K was 4.71 g/cm3(the relative density was 95.5%), and the maximum power factor was 0.058 mW/mK2 at 650K.抄録全体を表示PDF形式でダウンロード (4292K) -
Hiroaki Suzuki, Hiroshi Okamura, Ryuzo Watanabe2003 年 50 巻 11 号 p. 937-943
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーThe (Zn0.98Al0.02)O ceramic is known to show high dimensionless figure of merit(ZT)at high temperature among the n-type oxide materials. But it has problem of the large lattice thermal conductivity compared with other thermoelectric materials. However the lattice thermal conductivity can be decreased by grain refining, and further improvement in the ZT value is possible. Thus we have tried to synthesize homogeneous (Zn0.98Al0.02)O powders with fine particles size by mechanical alloying(MA), and make the fine grained and dense (Zn0.98Al0.02)O ceramic under several sintering conditions, expeceting the increase of ZT value due to the decrease in lattice thermal conductivity. We found an optimum MA condition for grain refinement, but homogeneous (Zn0.98Al0.02)O powders could not be obtained under present MA conditions. The fine grained and dense (Zn0.98Al0.02)O ceramic obtained by MA/HP process shows the decrease in lattice thermal conductivity. Hot pressing was found to decrease the absolute value of Seebeck coefficient and increase the electrical conductivity as compared with the normal sintering (NS). MA/HP process will increase the amount of the substituted Al for Zn. The ZT value became the maximum by the MA/NS; ZT=0.13 at 1073K.抄録全体を表示PDF形式でダウンロード (3672K) -
Shigeru Katsuyama, Yoshiki Takagi, Mikio Ito, Shigeta Hara2003 年 50 巻 11 号 p. 944-947
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーWe have synthesized ZnO ceramics added with Ag or Y by the polymerized complex method. The microscopic structure and the thermoelectric properties such as Seebeck coefficient, electrical resistivity and thermal conductivity of the materials are much affected by the added elements. Ag metal or Y2O3 oxide was observed as a second phase in the sintered Ag-or Y-added samples, respectively. The crystal grain size of the Ag-or Y-added samples is much smaller than that of the non-added samples. The absolute values of the Seebeck coefficient and electrical resistivity for the Y-added samples increase with an increase of the Y content, while those for the Ag-added samples are almost constant independent of the Ag content. More reduction in the thermal conductivity was observed in the Y-added samples. These behaviors are ascribed to the physical properties of the precipitated second phases.抄録全体を表示PDF形式でダウンロード (2365K) -
Hiroshi Okamura, Ryuzo Watanabe2003 年 50 巻 11 号 p. 948-951
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーSynthesis of AgSbTe2/Ag2Te composite by mechanical alloying from elemental powders is described. Mechanical alloying was done by vibratory ball milling with a ball-to-powder ratio of 100:1. The studied composition range was Sb2Te3-xmol%Ag2Te (x=43-70); the (β+Ag2Te) region in the Sb2Te3-Ag2Te phase diagram. XRD analysis showed that after sufficient milling β compound AgSbTe2 was found to be formed for x=43. The composites of various compositions were formed depending on the initial mixing ratios. The sintered compacts of the mechanically alloyed powders had homogeneous composite microstructures and exhibited the increase in the connectivity of the second phase Ag2Te in the AgSbTe2 matrix with increase in the Ag2Te content.抄録全体を表示PDF形式でダウンロード (5042K) -
Mikio Ito, Yoshimitsu Oda, Shigeta Hara2003 年 50 巻 11 号 p. 952-957
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーThe citric acid complex (CAC) process and subsequent pressureless sintering were explored towards the synthesis of a c-axis oriented NaxCo2O4 thermoelectric polycrystal. The effects of the CAC process on the shape of powder precursor, crystallographic anisotropy of a sintered compact and its thermoelectric properties were investigated. The CAC process provided a plate-like powder precursor composed of the γ-NaxCo2O4 phase, reflecting its layered crystal structure. During compacting and sintering of this powder, the plate-like grains were well aligned along the pressed plane because of their specific shape, resulting in the sintered body with large crystallographic anisotropy. The CAC method was also effective for synthesizing the sample with compositional homogeneity and fine microstructure. The electrical resistivity of the CAC sample was almost the same as that of the sample prepared by the conventional solid state reaction method in spite of the fine microstructure, because of its high degree of c-axis orientation. The Seebeck coefficient was significantly improved by adopting the CAC method, resulting in the large enhancement of the power factor.抄録全体を表示PDF形式でダウンロード (1996K) -
Shoko Kikuchi, Kenta Takagi, Jing-Feng Li, Ryuzo Watanabe2003 年 50 巻 11 号 p. 958-962
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーLanthanum-modified lead zirconate titanate (PLZT) ceramics possess photostrictive effect that is applicable to photo-driven and wireless actuators. The photo-induced strain is expressed in a product of piezoelectric constant and anomalous photovoltage, and it is theoretically explained that grain size reduction enhances photovoltage. Finegrained PLZT ceramics that have mean grain sizes of 2.0-0.2μm were prepared through the mechanical alloying (MA) synthesis and normal or hot-press sintering process. Their piezoelectric constant, dielectric constant and electric resistivity up to a grain size of 0.5μm were not dependent on grain size and agreed with the conventional one. The photovoltage significantly increased with a decrease in grain size. These results suggested that a lowering of grain size by MA leads to a remarkable improvement of the photo-induced strain value without a decline in strain response. However, the photo-induced strain value within grain size less than 0.5μm extremely declined due to a little remnant polarization. The photo-induced strain with illumination of 15mWcm-2 intense was maximally estimated to be 1×10-4.抄録全体を表示PDF形式でダウンロード (1996K) -
Tomio Satoh, Hua-Nan Liu, Michiru Sakamoto, Yuji Kawakami, Keisaku Ogi2003 年 50 巻 11 号 p. 963-967
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーThe MA-SPS (mechanical alloying followed by spark plasma sintering) process was adopted to further improve the high temperature properties of a newly developed 36Cr white cast iron (a eutectic Fe-36Cr-9Ni-5Mo-0.45Si-2.2C alloy). α-Al2O3 powder with a mean diameter of 0.4μm was used as reinforcement for the MA material, and the volume fractions of Al2O3 in the composites were 10% and 30%. The results show that the microstructures of the MA materials were greatly refined compared to those of the conventionally solidified ingot and that their high temperature hardness and high temperature abrasive resistance were considerably improved. Also found was that the increase in the volume fraction of the Al2O3 powder increased both the hardness and the abrasive resistance of the composite materials.抄録全体を表示PDF形式でダウンロード (3545K) -
Hirotaka Kato, Masahiro Takama, Kazuo Washida, Yoshinori Sasaki, Setsu ...2003 年 50 巻 11 号 p. 968-972
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーMechanical properties and sliding wear characteristics of Cu-10mass%Sn composites containing graphite or molybdenum disulfide (MoS2) produced by powder metallurgy techniques were investigated in order to develop a suitable self-lubricating and anti-wear material for use under dry sliding conditions. Graphite and MoS2 powders were coated with copper for the purpose of promoting the bonding between a copper particle and the lubricant particle during the sintering process. The hardness, microstructure, bending strength, wear and coefficient of friction of the sintered specimens were examined. It was found that the mechanical properties of the composites decreased with increase of the amount of addition of graphite or MoS2. However, the use of the copper-coated lubricant powders improved the strength. Graphite addition was very effective in reducing the wear and friction. Moreover the wear rate of the copper-coated graphite specimens was much smaller than that of the uncoated graphite specimens. By contrast, the wear rates of the MoS2 composites increased considerably with the amount of MoS2 addition. This behavior is thought to be due to the absence of MoS2 and the presence of brittle CuMo2S3 compounds in the sintered composites.抄録全体を表示PDF形式でダウンロード (1713K) -
Kiyoshi Nomura2003 年 50 巻 11 号 p. 973-975
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーPerovskite related oxides such as (Ba, Ca)(Fe, Co)O3-δ, (Sr, Ca)(Fe, Co)O3-δ and (Ba, Ca)(Fe, Mg)O3-δ have been developed as safety materials for quick solidification of CO2 at high temperatures. The CO2 solidification properties and microstructures were investigated. Perovskite oxides (ABO3) become active for CO2 accommodation due to the lattice distortion produced by mixing different alkaline earth ions in site A and the mixed valence states by substitution of Fe ions by Cc and Mg ions in site B. The mechanism of rapid CO2 accommodation was taken into consideration.抄録全体を表示PDF形式でダウンロード (281K) -
Nurul Taufiqu Rochman, Hidekazu Sueyoshi2003 年 50 巻 11 号 p. 976-980
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーFe-C system alloys were prepared by mechanical alloying and powder metallurgy (MA-PM). Elemental powders of iron and graphite with various carbon concentrations were mechanically alloyed (MAed) by using a planetary ball mill in argon atmosphere. The MAed powders were then characterized by X-ray diffraction (XRD), differential thermal analysis (DTA) and scanning electron microscopy (SEM). During MA, the particle refinement, formation of super-saturated solid solution and Fe/C amorphous occur and their degrees are influenced by carbon concentration in the mixed powders. The MAed powders with 4-10 mass% carbon concentration were hot isostatic pressed (HIPed) and with 0.4-2 mass% were hot pressed (HPed) at both lower and higher temperatures than the eutectoid transformation point A1. The sintered compacts were characterized by Vickers hardness test, tensile test and scanning electron microscopy (SEM). Both the HIPed and HPed compacts obtained in the present study have very fine microstructures in which very fine cementite dispersed in very fine ferrite matrix. Mechanical properties of the HPed compacts of Fe-C system with hypo-eutectoid composition are comparable with those of standard steels. Thus, MA and PM is a new technique of near net-shape to gain steels with excellent mechanical properties without thermal refining and alloying elements.抄録全体を表示PDF形式でダウンロード (1978K) -
David L. Bourell, Joseph J. Beaman2003 年 50 巻 11 号 p. 981-991
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーFreeform fabrication as a technology is 25 years old, although its antecedents date back over 100 years. A brief historical context for freeform fabrication will be presented. Included is an introduction to current techniques and overview of the processes. The presentation will close with a review of current applications and future possibilities.抄録全体を表示PDF形式でダウンロード (7839K) -
Kenji Doi, Kazuki Hanami, Tsuneo Teraoka, Syuntaro Terauchi, Takashi S ...2003 年 50 巻 11 号 p. 992-995
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーHigh cycle fatigue properties of Metal Injection Molded (MIM) cold work tool steel and wrought steel (JIS SKD11) were investigated via ultrasonic fatigue test. The wrought steel specimens were tempered at 423 K for 1 hour. On the other hand, the MIM steel specimens were tempered at various temperatures in order to evaluate effect of tempering temperature on fatigue property. The ultrasonic fatigue tests were performed in the fatigue life range of N=103-108. Fatigue strength of the MIM steel specimens was equivalent to that of the wrought steel specimens. Fatigue strength of the MIM specimens declined with increasing tempering temperature. The results of microstructure observation showed that the diameter and shape of carbide of the MIM specimens were more uniform than those of the wrought steel specimens.抄録全体を表示PDF形式でダウンロード (3395K) -
Xuanhui Qu, Xinbo He2003 年 50 巻 11 号 p. 996-1000
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーUniversity of Science and Technology Beijing (USTB) is one of the key universities that are directly under the guidance of China Ministry of Education. Powder metallurgy activities have been carried out at USTB for about 50 years. Beijing Key Laboratory for Advanced Powder Metallurgy and Particulate Materials, which was founded on the base of Department of Powder Metallurgy at USTB, is a comprehensive base for PM education, research and development in China. In this paper, some of the current research activities and achievements in this laboratory are introduced, including ultra-fine grained cemented carbides made from nanometer powders, W-Cu and Mo-Cu alloys for electronic packages, SHS process and its applications, warm compaction, and powder injection molding.抄録全体を表示PDF形式でダウンロード (5175K) -
Yang Cao2003 年 50 巻 11 号 p. 1001-1003
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーNingbo Tongmuo New Materials Co., Ltd. (NBTM), which specializes in manufacturing PM components, has been enjoying rapid growth since 1995. This article gives a brief introduction of NBTM, as one of the largest manufacturers of sintered metal structural components in China.抄録全体を表示PDF形式でダウンロード (5012K) -
Kuan-Hong Lin, Chen-Sheng Hsu, Shun-Tian Lin2003 年 50 巻 11 号 p. 1004-1008
発行日: 2003/11/15
公開日: 2009/05/22
ジャーナル フリーAlloying Mo into W-Ni-Fe heavy alloys results in solid solution strengthening of the matrix phase and yields smaller tungsten grains. However, a high alloying concentration of Ma causes a high concentration of Mo in the matrix phase at the final stage of liquid phase sintering. When the concentration of Mo in the liquid phase exceeds a critical value, a MoNi type intermetallic phase heterogeneously nucleates and grows on the surface of W-Mo grains during cooling, which imparts brittleness to the alloys. This article summarizes the recent studies regarding the effect of Mo on the microstructural evolution and mechanical properties of tungsten heavy alloy. In addition, the mechanism behind the formation of the intermetallic phase is emphasized.抄録全体を表示PDF形式でダウンロード (5482K)
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