巻号一覧
42 巻, 8 号
選択された号の論文の16件中1～16を表示しています
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星野 孝二, 河野 通, 森川 正樹1995 年 42 巻 8 号 p. 871-875
発行日: 1995/08/15
公開日: 2009/12/04
ジャーナル フリーPrecious Metals Plasticine (PMP), a mixture of precious metal powder and organic binder, has been developed. By using it, various shapes of precious metals can be made easily by hand forming, just as with paper clay or potter's clay. The dried PMP can be carved just as gypsum or plaster of Paris. Hollow parts can be also made from the clay using a clayey core material. PMP sheet has also been developed by changing the composition of binder, and it can be folded into figure. In this paper, the manufacturing processes and properties of PMP is described and some applications are introduced.抄録全体を表示PDF形式でダウンロード (2786K) -
寺岡 利雄1995 年 42 巻 8 号 p. 876-883
発行日: 1995/08/15
公開日: 2009/05/22
ジャーナル フリーSevere wear of pantograph contact strips are caused by electric arc between contact strips and overhead wires. Arc-resistant contact strips for conventional rolling stocks were developed. They are made of sintered copper alloys. They contain hard metal such as Cr or Fe-Mo to improve wear resistance and MoS2 or Cu2S-FeS, in place of graphite, to improve arc resistance and lubricity.
New type lubricants for contact strips were developed to suppress wear of contact stirps and the overhead wires. They are made of wax containing graphite to improve eletcric conductivity.
New type contact strips made of carbon for conventional rolling stocks were developed to suppress wear of overhead wires. They contain metal to improve electric conductivity and mechanical properties. They are going to use widely in JR lines.
Wear of contact strips of the Shinkansen was investigated and it became evident that wear can be expressed by the function of velocity of the rolling stocks, collected current and material constants. It also became clear that electrical wear is more severe than mechanical wear.
New contact strips made of sintered iron alloys for the Shinkansen were developed. They contain hard metal such as Cr, Fe-W or Fe-Mo to improve wear resistance and MoS2 or impregnated low melting point metal to improve lubricity of them.抄録全体を表示PDF形式でダウンロード (469K) -
浅香 一夫1995 年 42 巻 8 号 p. 884-890
発行日: 1995/08/15
公開日: 2009/05/22
ジャーナル フリーThis report indicates the technical key-points of diffusion bonding method of ironbased green compacts during sintering comparing with the sinter-fit bonding method and some applications.
The key-points are the material selections for assembled compacts which should be based on the difference of thermal expansion curves of both materials during sintering, the additive elements selections which should be based on the diffusion coefficient into iron, the fit clearance which should be maintained in the region of press fitting, the shape of iron powders and densities of green compacts.
Most of applications of this technique are complex shaped parts of copy machines. And recently, the production of automotive engine parts is also started using this technique.抄録全体を表示PDF形式でダウンロード (6455K) -
小野田 岑夫1995 年 42 巻 8 号 p. 891-899
発行日: 1995/08/15
公開日: 2009/05/22
ジャーナル フリーStarting with the analysis of Japanese P/M industries in the automobile market and other metal forming technology, the author argues that competitiveness of P/M parts comes mainly from its powder compacting process which can form complicated profiles of parts at better precision. In order to develop P/M parts market, new metal compacting methods of complicated profiles which could be machined only by end-milling are emphasized in this paper and the developments of special gear pump rotor and multi-step powder compaction which have enabled the innovation of mechanics design of automobile, are introduced as typical examples of this development strategy.
The prospect to the possible subjects which might be the key technologies which could open new market is also discussed based on the trend of P/M Darts.抄録全体を表示PDF形式でダウンロード (5860K) -
高橋 俊行, 勝村 祐次, 鈴木 寿1995 年 42 巻 8 号 p. 900-904
発行日: 1995/08/15
公開日: 2009/12/04
ジャーナル フリーThe A1203 ceramics having additional MgO of 50-5000 mass ppm (grain size of starting powder, 0.2 μm) was prepared by sintering at 1523-1623K and then HIP treatment at 1473K. The microstructure and transverse-rupture strength at room temperature were mainly studied as a function of MgO content. It was found that the strength of ceramics having MgO of 100-500ppm reached to about 1.3GPa at maximum, with the uniform grain size of 0.8-0.9 μm, and that the strength of ceramics having higher MgO content sharply decreased in spite of the same grain size, probably because of the spinel formation. The creep strength of Al2O3 ceramics lowered with increasing room temperature strength. It was suggested that the grain size of A1203 ceramics was necessary to be minutely controlled according to the application temperatures.抄録全体を表示PDF形式でダウンロード (5395K) -
池田 保之, 高木 節雄1995 年 42 巻 8 号 p. 905-910
発行日: 1995/08/15
公開日: 2009/12/04
ジャーナル フリーCrashed metallic Cr, atomized Ti and HDt1 Ti powders were mixed to the composition of Ti-4mass%Cr with varying the powder ratio of (HDH Ti/atomized Ti), and the strength of green compacts produced by the die-compaction method were evaluated, The sintering properties of green compacts were also discussed as a function of the volume fraction of HDH Ti powder.
The green compacts without HDH Ti powder are sufficiently densified because the atomized Ti powder used has a wide distribution in the powder particle size. However, the bending strength of green compacts is very low, because the powder/powder interface is flat. The densification of compacts by sintering is little due to the large particle size, while there is a benefit that the shrinkage during sintering is very small (about 1%). The strength of green compacts is greatly enlarged with increasing the volume fraction of HDH Ti powder, because HDH Ti particles tangle each other. The size of HDH Ti powder is much lower than that of atomized Ti powder, therefore, the densification by sintering is also promoted with the increased volume fraction of HDH Ti powder. Since the shrinkage of compacts during sintering becomes larger by addition of HDH Ti powder, the adequate volume fraction of HDH Ti powder should be determined by taking the compactibility, sintering property, shrinkage of products besides mechanical properties into consideration.抄録全体を表示PDF形式でダウンロード (3195K) -
池田 保之, 高木 節雄1995 年 42 巻 8 号 p. 911-917
発行日: 1995/08/15
公開日: 2009/12/04
ジャーナル フリーCompacts of Ti-4mass%Cr alloy with various porosity and oxygen content were produced from the mixture of crashed metallic Cr, atomized Ti and HDH Ti powders, and then sintered at 1473K for 3.6ks. Effects of pores and oxygen content on mechanical properties were examined in the sintered Ti-4mass%Cr alloy by means of optical microscopy, analysis of oxygen content, measurement of porosity and tensile tests.
The tensile strength of sintered compacts increases with increasing the volume fraction of HDH Ti powder, because the porosity of sintered compacts is decreased and the shape of pores becomes spherical due to the excellent sintering property of HDH powder. The oxygen content of sintered compacts also increases with increasing the volume fraction of HDH powder, owing to the higher oxygen content in HDH Ti powder than atomized Ti powder. Microstructures of sintered materials are of (a+β) two-phase characterized by fine platelet a phase. The phase ratio a/β and the microstructure of sintered materials don't depend on the volume fraction of HDH Ti powder in spite of having different oxygen content. Consequently, the strength of a sintered Ti-4mass%Cr alloy is greatly influenced by the solid solution of oxygen and by the shape and volume fraction of pores. Especially, when the shape of pores is angular, stress concentration at the corner of pores results in a significant decrease in the tensile strength and elongation.抄録全体を表示PDF形式でダウンロード (3405K) -
Than Min Kyaw, Yasunori Okamoto, Kunio Hayashi1995 年 42 巻 8 号 p. 918-925
発行日: 1995/08/15
公開日: 2009/05/22
ジャーナル フリーThe tetragonal to monoclinic (t-to-m) phase transformation of 2 mol% yttria-stabilized zirconia appeared during cooling when it was incorporated in mullite matrix phase. This transformation was significantly enhanced with increase in zirconia volume fraction and length of exposure at the high temperatures (>1600°C). High internal stresses of a tensile nature which develop in the zirconia grain owing to the large difference in thermal expansion coefficients of mullite and zirconia, the lack of yttria in solid solution in zirconia due possibly to some yttria that reacted with alumina and/or silica from mullite during sintering, and the zirconia grain coarsening were believed to be responsible for the enhanced phase transformation. An analytical model showing thermal stress configurations and empirical correlations pertaining to the existence of grain boundary glass phase were presented. The t-to-m phase transformation of zirconia in composites occurred at temperatures between 610°and 700°C during cooling which could be identified in the dilatation curves. The temperature for start of the martensitic phase transformation (M5) gradually shifted to higher temperatures with increase in ZrO2 volume fraction and, for a given composition, increase in number of cycles.抄録全体を表示PDF形式でダウンロード (4982K) -
韓 剛, 多田 充伸, 黒木 英憲, 篠崎 賢二1995 年 42 巻 8 号 p. 926-932
発行日: 1995/08/15
公開日: 2009/05/22
ジャーナル フリーThe sintering of stainless steel powder (-100 mesh water-atomized SUS316L powder ) compacts by use of fluxing has been tried. As a result, it was found that the sintering was activated noticeably by the addition of a small amount of flux. A sintered density of 94.5% was achieved with a 2mass% of Na2B4O7 as the flux for a compact having a green density of 77.2% by sintering it at 1620K for 60min in vacuum. Without the flux, a compact sintered in the same conditions had a density of 85.4%. We think the enhancement of the sintering is associated with the removal of oxide from the surface of the steel particle and the liquid phase sintering following the formation of a Fe-Cr-B eutectic liquid. The flux became a slag including SiO2, MnO and Na2O in the spherical pores during sintering.抄録全体を表示PDF形式でダウンロード (3279K) -
宮本 欽生, 栗 振思, 康 燕生, 谷畑 公昭1995 年 42 巻 8 号 p. 933-938
発行日: 1995/08/15
公開日: 2009/12/04
ジャーナル フリーHyperfunctional Al2O3 ceramics with symmetrically graded structures of the A12O3/TiC/ Ni/TiC/Al2O3 and Al2O3/Cr3C2/Ni/Cr3C2/Al2O3 were fabricated by SHS/HIP. The SHS/HIP is both a new sintering process of such heterogeneous materials with different sintering tempreratures and a recycling process using a chemical oven of Si waste in zinc smelting. Strong residual compressive stress of 200-800 MPa were produced in the outer Al2O3 layers mainly due to the thermal expansion mismatch between the outer Al2O3 and inner cermet layers. The compressive stress acted to enhance intrinsic toughness and hardness of Al2O3. Moreover, the local stress change produced by the surface damage reached to the opposite side through disturbance of the internal stress balance of compression/tension/ compression designed in these materials. This effect is potentially available to give a damage detectable function.抄録全体を表示PDF形式でダウンロード (3334K) -
上平 一茂, 眞岩 幸治, 後藤 建次郎, 本多 均一, 藤井 忠行1995 年 42 巻 8 号 p. 939-943
発行日: 1995/08/15
公開日: 2009/05/22
ジャーナル フリーUsing metallic ingots of Y-Cu and Cu-Ba alloys made by both an electron beam- and/or arcmelting, refined alloy oxide powders of various purity grades for the ceramic superconductors YBCO(123) were prepared by the conventional grinding and firing techniques. Bulk specimens of YBa2Cu30x, which were fabricated by both sintering and melt-growth methods using these refined alloy oxide powders as starting materials, were characterized by the measurements of Tc and Jc. It is noted that these specimens showed a tendency to have higher Jc values, as compared with the specimens prepared from chemical reagents of Y203, BaC03 and CuO. Such results are interpreted in terms of the commercial and physical variations and changes in microstructures of specimens induced by the use of different starting materials, refined alloy oxide powders or commercial oxide reagents.抄録全体を表示PDF形式でダウンロード (1751K) -
山本 剛久, 片村 淳二, 秦 西平, 佐久間 健人1995 年 42 巻 8 号 p. 944-947
発行日: 1995/08/15
公開日: 2009/05/22
ジャーナル フリーMechanical alloying (MA) of ZrO2-8mol%ZrN system is exmained. XRD peaks from the mixed powders in ZrO2-8mol%ZrN consist of m-ZrO2 and ZrN with NaCl strucrure. After MA for 80h of the powders, the peak intensity from m-ZrO2 and ZrN was reduced and new peaks appeared. The new peaks can be indexed to be cubic fluorite structure or pseudofluorite structure. Nitrogen must be in solution during mechanical alloying, and a high-temperature form of ZrO2 is stabilized.抄録全体を表示PDF形式でダウンロード (241K) -
津田 大, 間渕 博, 中山 豊1995 年 42 巻 8 号 p. 948-953
発行日: 1995/08/15
公開日: 2009/05/22
ジャーナル フリーThe Cu-based composites are excellent candidates for applications that require a high strength and a good electrical conductivity. Recently, combustion synthesis or self propagating, high-temperature synthesis (SHS) using powder compacts has been developed to produce intermetallics or ceramics. It is also possible to form metal-intermetal li c or metal-ceramic composites from combustion reactions between corresponding elemental constituents. It has the advantage of an in-situ forming technique compared with conventional artificial comosite production approaches.
In the present study, combustion reaction was carried out to form Cu-based composites in the Cu-Ti-BN system. The compacts of Cu and Ti powders with BN powder reacted exothermically, and formed a mixture product which had a fine distribution of the TiB2 and TiN particles in the Cu matrix. The processing technique, therefore, is of interest as a combustion reaction synthesis to make in-situ metal-based composite materials.抄録全体を表示PDF形式でダウンロード (5428K) -
落合 鍾一1995 年 42 巻 8 号 p. 954-959
発行日: 1995/08/15
公開日: 2009/05/22
ジャーナル フリーNiAl-Y2O3 composites with 0, 5, 15 and 20vol%Y2O3 were fabricated by mechanical alloying (MA)-mechanofusion (MF)-hot press (HP) process. Starting powders were pure Ni, pure Al and Y2O3 powders. Morphological change of powders during (MA+MF) process was studied. In addition, the microstructures and the mechanical properties of sintered specimens were investigated. Fine MAed powders with diameter of less than 10μm were able to be spheroidized by MF process. The formation of NiAl phase during MA was definitely confirmed. Sintered composites basically consist of NiAl matrix and uniformly dispersed Y2O3 particulates, though the small amount of other phase was found for high volume Y2O3 alloys. Vickers hardness and 0.2% flow stress increased with increasing volume fraction of Y2O3, suggesting the dispersion strengthening. Fracture stress, markedly larger than the flow stress, also increased with volume fraction of Y2O3 and monotonously decreased with temperature. All specimens fractured with compressive plastic strain of 5-10% at from room to intermediate temperature. At over 800K, the fracture strain increased remarkably.抄録全体を表示PDF形式でダウンロード (3200K) -
朝日 信夫, 野口 晴司1995 年 42 巻 8 号 p. 960-963
発行日: 1995/08/15
公開日: 2009/05/22
ジャーナル フリーAl75Cu15V10 powder mixture was mechanically alloyed in a conventional planetary ball mill under an Ar atmosphere. The alloying process and the structure change induced by additional heating were investigated using X-ray diffractometry and differential scanning calorimetry. An amorphous alloy was obtained directly in the powder milled for 15 to 30h. The amorphous alloy obtained after 20h of mechanical alloying showed that by subsequent heating the amorphous to Mackay type icosahedral phase transition occurred in the region between 720 and 740K. The interatomic distances and coordination numbers of nearest neighbors in the amorphous and the Mackay type icosahedral alloys were determined from the principal peak of the radial distribution functions. It was found that atomic structures of these alloys were very similar to those of the same composition prepared by liquid quenching.抄録全体を表示PDF形式でダウンロード (217K) -
Yutaka Hiraoka, Tetsuji Hoshika, Myoung Ki Yoo, Choi Ju1995 年 42 巻 8 号 p. 964-968
発行日: 1995/08/15
公開日: 2009/05/22
ジャーナル フリーIn order to investigate the effect of specimen size on the strength and the ductility of molybdenum, bend angles at temperatures between liquid nitrogen temperature and room temperature were carried out for the recrystallized sheet of molybdenum doped with pottasium-silicate. In this study the low-temperature fracture strength and ductility of the material were represented by critical stress and critical temperature, respectively.
The results are summarized as follows.
(1) As the specimen width decreased from 4mm to 1mm with the specimen thickness being 1mm, the critical stress tended to increase whilst the yield strength was almost unchanged.
(2) Increase of the critical stress with decreasing the specimen width was related with the crack generation and propagation characteristics. The size of the crack generation site tended to be smaller, as the specimen width decreased.
(3) The critical temperature tended to decrease as the specimen width decreased. This result was attributed mainly to the increase of the critical stress.抄録全体を表示PDF形式でダウンロード (1494K)
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