巻号一覧
45 巻, 4 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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岡村 清人1998 年 45 巻 4 号 p. 292
発行日: 1998/04/15
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) -
趙 源丞, 林 宏爾1998 年 45 巻 4 号 p. 293-301
発行日: 1998/04/15
公開日: 2010/07/12
ジャーナル フリーThis manuscript is the summary of the results of our studies on the effects of the kind and amount of sintering aids, orientation of silicon carbide whisker {SiC(w)} and evaluation method on the room temperature mechanical properties of SiC(w)/Si3N4 hot-pressed composite ceramics, which was talked in the memorial presentation assigned for the winner of “JSPM Award for Research Advancement”. The main results are as follows: I. Effect of Sintering Aids;(1)The effective sintering aids and the amount for the enhancement of fracture toughness (KIC) of the composite are the ones such that needle-like Si3N4 grains with large size or large axial ratio develop during sintering, in the same way as the Si3N4 monolithic ceramics.(2)The transverse-rupture strength (TRS) was considerably affected by the size of fracture source such as SiC(w) aggregate as well as KIC, although the value of TRS of our specimens was higher than those in the other researchers' reports. (3) Er2O3 is an effective sintering aid in a similar way to Y2O3 for obtaining higher KIC and TRS. II. Effect of Arrangement of SiC(w); (1) The unidirectional arrangement of SiC(w) to the axis of the specimen sharply increases KIC from 6.0MPa⋅m1/2 to 9.4MPa⋅m1/2. (2) The enhancements of KIC by the arrangement of SiC(w) as well as the addition are not explained by the conventional theory, i.e., “crack deflection effect”, but mainly by “load transfer effect”. III. Effect of Evaluation Method; (1) The KIC measured by CSF method (the shape of pre-crack is semi-ellipse) are nearly the same for VV and PV specimens (the characteristics are shown in Fig.6 in the text). The KIC measured by SEPB method where the shape of pre-crack is rectangle, however, was higher for VV specimen; the anisotropy of KIC was detected only by SEPB method. These results are explained by the difference of three-dimensional average angle (θ3) of the intersection of the pre-crack or propagating crack to the longer axes of SiC(w) and needle-like Si3N4 grains among the kinds of specimen and method, although these can not be explained by the difference of two-dimensional angle on the tensile surface. (2) This indicates that the method for evaluating KIC should be selected, taking into consideration the value of θ3 as well as two-dimensional angle or the microstructure of the composites.抄録全体を表示PDF形式でダウンロード (6261K) -
落合 庄治郎, 北條 正樹1998 年 45 巻 4 号 p. 302-308
発行日: 1998/04/15
公開日: 2009/05/22
ジャーナル フリーMechanical behavior of fiber-composites is strongly affected by the interface between the fiber and matrix. In this paper, recent modeling study on influences of interface on strength of (A) coated fiber whose coating layer is precracked and (B) multi-filamentary composistes in which brekages of fiber, matrix and interface occur at various locations, accumulating with increasing applied stress and determine the overall strength, was reviewed. From these results, the necessary conditions to achieve high strength through interfacial control were mentioned.抄録全体を表示PDF形式でダウンロード (6261K) -
山岸 千丈, 塚本 惠三, 塩貝 達也1998 年 45 巻 4 号 p. 309-315
発行日: 1998/04/15
公開日: 2009/12/04
ジャーナル フリーEffects of microstructures and additions of secondary phases in sialon ceramics on strength, fracture toughness and fatigue properties were investigated to obtain the composites based on sialon ceramics with high reliability for both rapid fracture and delayed failure. The addition of SiC particles increased the creep resistance at elevated temperature because of decreasing the amount and the thickness of intergranular glassy phase. In-situ-toughened sialon with elongated grains have high fracture toughness and high strength. On the other hand, oxide content in the intergranular phase and grain size affected slow crack growth attributable to the stress corrosion by humidity in air, and fatigue under cyclic loading was remarkably accelerated in the material with coarse grains. SiC whisker in insitu-toughened sialon improved fatigue properties at room temperature and the creep resistance without decreasing its strength and fracture toughness.抄録全体を表示PDF形式でダウンロード (9676K) -
杉森 将宣, 李 敬鋒, 渡辺 龍三1998 年 45 巻 4 号 p. 316-320
発行日: 1998/04/15
公開日: 2009/05/22
ジャーナル フリーFine powders of SiC-A1N ceramic alloy were synthesized by direct reactions of a powder premix of Si, C and Al powders in nitrogen, i.e. Si+C+xAl+(x/2)N2=SiC:xAIN. The synthesized powders showed a good sinterability; dense compacts were fabricated by hot-isostatic pressing at relatively low temperature (2123K) without additives, or by pressureless sintering with Y2O3 as a sintering additive. The obtained SiC-A1N alloys showed better mechanical properties than the monolithic SiC and A1N; for example a two to threefold increase in fracture strength was achieved.抄録全体を表示PDF形式でダウンロード (3917K) -
Takeshi Ohtsuka, Hiroshi Mabuchi, Hiroshi Tsuda, Kenji Morii1998 年 45 巻 4 号 p. 321-325
発行日: 1998/04/15
公開日: 2009/05/22
ジャーナル フリーUsing elemental powders, reactive hot-pressing was carried out to prepare Si3N4/SiC composite ceramics. Silicon and graphite powders with additives (Al2O3 and Y2O3) were reacted at 1873K in gaseous nitrogen (0. 15MPa) and hot-pressed at 2073K for 7.2ks with applied pressure of 70MPa, and finally formed a Si3N4(β-Si3N4)-SiC(β-SiC) composite with a small amount of glassy and crystalline phases from additives. The resulting composites had 12-34vol%SiC, and the SiC grains were granular with sizes of about 0.1-1μm, and homogeneously distributed and well bonded to the matrix Si3N4. On the other hand, the Si3N4 matrix grains were rod-like in shape with sizes of 0.3-3μm. It was found that the composite ceramics had a relatively higher bending strength at both ambient and elevated (at 1423K) temperatures; about 1000 and 700 MPa, respectively. Fracture toughness of 5.3 MPam1/2 was obtained by indentation fracture tests. It was evident that reactive hot-pressing was very effective process for in-situ synthesis of Si3N4/SiC composite ceramics.抄録全体を表示PDF形式でダウンロード (3727K) -
Wen-bo Du, Kiyohiko Tatsuzawa, Tatsuhiko Aizawa, Junji Kihara1998 年 45 巻 4 号 p. 326-329
発行日: 1998/04/15
公開日: 2009/05/22
ジャーナル フリーThe cold swaging over the reduction of 90% is found to be effective to improve the final relative density to that for a bulk, sintered billet and to reduce the final grain size to be half. Due to the grain size reduction and high densification, the hardness of resintered Al2O3 billet becomes equal to or larger than that of bulk, dense Al2O3.抄録全体を表示PDF形式でダウンロード (318K) -
Rajagopalan Ramaseshan, S. Krishnamoorthy Seshadri, N. Gopalakrishna N ...1998 年 45 巻 4 号 p. 330-335
発行日: 1998/04/15
公開日: 2009/05/22
ジャーナル フリーThe γ-TiAI/Ti2AlC composites with and without impurities, Ni, Cl and P, were prepared by combustion reaction from the elemental powders and homogenized after arc melting. The resulting composition is about 18 vol% Ti2AlC in the matrix of TiAl with a lamellar structure of Ti3Al (α2). In the homogenized specimens, the α2 phase transforms to the precipitated Ti2A1C particles in the place of solutionizing lamellar structure. The composite material has a high strength both at ambient and elevated temperatures; about 800 and 400 MPa, respectively, with an ambient temperature ductility of 0.7% at bending test. The fracture toughness test also proves the composite homogenized is better than the as cast and value is 17.8 MPam1/2. The crack propagation in the homogenized composite is zigzag mode and the precipitated particles are main obstacles for the crack propagation. The composite with impurities shows a marginal improvement in the oxidation resistance over the composites without impurities.抄録全体を表示PDF形式でダウンロード (6211K) -
山成 真市, 間渕 博, 津田 大, 森井 賢二1998 年 45 巻 4 号 p. 336-340
発行日: 1998/04/15
公開日: 2009/05/22
ジャーナル フリーTo improve low room-and high-temperature strength of titanium alminides, TiAI based composites reinforced with TiB2 and Ti2AIN particles were made by combustion reaction process using Ti-AI-BN powder mixtures, and arc-melted for densification. The powder compositions included Ti47.4Al44.2(BN)8.4, Ti49.0Al42.6(BN)8.4 and Ti50.5Al41.1(BN)8.4 in at%, corresponding to matrix composition of Ti48Al52, Ti50Al50 and Ti52Al48, respectively. The volume fraction of reinforced particles was about 18%. The as cast specimens had a matrix of TiAl(γ) with a lamellar structure of Ti3Al(α2). In the annealed specimens, such lamellar structures were completely or partially disappeared, while smaller particles (about 100-200nm) were observed in the matrix of all specimens. These particles were found to be MAIN and mainly formed in place of disappeared Ti3Al in the lamellae. The formation of these particles was attributed to different solubility limit for nitrogen in yand α2 and solutionizing α2 phase by heat treatment. It was found that the composite materials had a high strength at both room and elevated(1173K) temperatures; 800-1100MPa and about 600MPa, respectively. The bending and fracture toughness tests also proved that the composite annealed is better than the as cast, and values were about 0.4% in ductility and 13-15 MPam in fracture toughness.抄録全体を表示PDF形式でダウンロード (6364K) -
杉山 明, 小林 慶三, 尾崎 公洋1998 年 45 巻 4 号 p. 341-345
発行日: 1998/04/15
公開日: 2009/05/22
ジャーナル フリーThe formation of ultra fine TiC dispersed alloy by mechanical alloying (MA) and spark plasma sintering (SPS) has been investigated. The composition of TixC100-x (x=50-80)-20mass%Ni(called cermet) and that of Ti50Nix C50-x (x=20-45) (called NiTi alloy) alloy powder have been synthesized by MA of three kinds of elemental powders. During MA, TiC-Ni consolidation was formed in the vessel for the composition of less than 65at.%Ti mixture. In the case of cermet, after MA, for the composition of more than 70at.% Ti mixture, C and Ni powders were added to MA powder in order to make the total composition of Ti50C50-20mass%Ni cermet. The powder mixture of cermet and NiTi alloy was consolidated by SPS method at 1073K. The size of sintered body was φ15×3mm. This sintered body consisted of TiC, Ni, and Ni-Ti alloy. It was found that the ultra fine TiC (<1000nm) had been formed during SPS process by using Ti75C25-20mass%Ni+C+Ni powder. This ultra fine TiC was dispersed homogeneously in the cermet. In the case of NiTi alloy, the fine TiC was not observed in the sintered sample. And the sample of Ti50NixC50-x alloy was very brittle.抄録全体を表示PDF形式でダウンロード (5378K) -
井上 明久1998 年 45 巻 4 号 p. 349-355
発行日: 1998/04/15
公開日: 2009/05/22
ジャーナル フリーRecent progress and present situation of high specific-sterngth Al-based alloys by the use of nonperiodic structure such as amorphous and quasicrystalline phases have been reviewed. Amorphous alloys with high tensile strength (σf) above 1000 MPa were obtained in Al-Ln-TM and Al-ETM-LTM (Ln=lanthanide metal, ETM= IV to VI group transition metal, LTM= VII and VIII group transition metal) systems by melt spinning and gas atomization. The warm extrusion of atomized amorphous powders caused the formation of bulk nanostructure (NS) alloys consisting of compounds (Al11Ln3 and Al3Ni) with a size of 50 nm embedded in fcc-Al phase with a grain size of 100 to 200 nm and the NS alloys exhibit high σf of 700 to 1000 MPa, elongation of 1 to 8 %, high fatigue strength of 300 to 350 MPa and high elevated-temperature strength of 300 MPa at 573 K. The Al-based NS alloys have been used in some application fields which require high specific strength. Bisides, bulk nanoquasicrystalline (NQ) alloys consisting of nanoscale icosahedral particles with a size of 20 to 70 nm surrounded by fcc-Al phase with a spacing of about 10 nm were produced by warm extrusion of atomized powder in Al-Mn-Ce, Al-Cr-Ce-TM, Al-Mn-TM and Al-Cr-TM systems. The NQ alloys also exhibited good combined mechanical properties, i. e., high σf of 500 to 800 MPa, large elongations of 5 to 35 %, high impact fracture energies reaching 180 kJ/m2 and high elevated temperature strength of 260 MPa at 573 K. These properties are much superior to those for conventional Al-based alloys and hence the NQ alloys are also expected to develop as a new type of high specific-strength material.抄録全体を表示PDF形式でダウンロード (6294K) -
平岡 裕, 平櫛 敬資1998 年 45 巻 4 号 p. 356-361
発行日: 1998/04/15
公開日: 2009/05/22
ジャーナル フリーDevelopment of a markedly excellent heat-resisting material may be possible by the combination of refractory metals and high-temperature ceramics. In this study joining between single-crystalline molybdenum and carbon-ceramics whose chemical composition and/or microstructure had been controlled was carried out by using precious metals (palladium, platinum) or active metal (zirconium). Fracture strength of the brazed joint was evaluated by the three-point bend tests at room temperature. Then the relation between the joint strength and the microstructure and/or chemical composition in and near the brazed layer was discussed.抄録全体を表示PDF形式でダウンロード (6044K) -
岩崎 智宏, 柳田 剛, 佐藤 宗武1998 年 45 巻 4 号 p. 362-367
発行日: 1998/04/15
公開日: 2009/05/22
ジャーナル フリーIn this paper, a compounding process in which fine WC powder was dispersed in particulate Ag-Ni alloy using a high-speed elliptical-rotor-type mill was investigated. In the process, the growth of the composite particle was observed as the processing time proceeds. A model for the growth phenomenon of the particle was constructed by means of theory of powder grinding using ball mill and dynamics of the plastic deformation of metal particle. In the model, the probability that the composite particle grew was adopted. It was expressed as the product of the probability that the particle was caught between a pair of media (zirconia beads), that it occurred the plastic deformation and the number of the rotor caught them, which included the experimental conditions as parameters. Temporal change in size distribution of the composite particles has been calculated using this method. Comparing calculated value with experimental data of particle median diameter, they were in good agreement. Consequently, it has been indicated that the model is valid and accurate estimation and control of particle size were possible.抄録全体を表示PDF形式でダウンロード (404K) -
川瀬 欣也, 柳川 弘毅, 森本 耕一郎1998 年 45 巻 4 号 p. 368-372
発行日: 1998/04/15
公開日: 2009/05/22
ジャーナル フリーEffects of high temperature sintering on mechanical properties of sintered low alloy steels were investigated using several commercial alloy powders. In order to evaluate the test data quantitatively, principal component analysis was employed.
With regard to sintering temperature dependence of mechanical properties, as-sintered steels were classified into two groups. Strength of Fe-4%Ni-1.5%Cu-0.5%Mo-(0.3-0.8)%C steels and ductility of Fe-(0.5-2)%Ni-(0-1.5)%Cu-l%Mo-0.5%C steels were improved by raising sintering temperature, while sintering temperature did not strongly affect ductility of the former steels and strength of the latter steels. It is considered that the influence of sintering temperature on mechanical properties varies depending on the Ni content of the steels.
On the other hand, when these steels were heat treated after sintering, both strength and ductility of the steels obtained by high temperature sintering were superior to those of the steels of a conventional sintering process.抄録全体を表示PDF形式でダウンロード (1933K) -
岸本 芳久, 山下 治1998 年 45 巻 4 号 p. 373-378
発行日: 1998/04/15
公開日: 2009/12/04
ジャーナル フリーNd-Fe-B alloy powder was granulated by a spray drying method using an organic binder in order to improve the powder flowability during feeding and compacting. In this experiment, the organic binder consisted of poly(methyl methacrylate) (PMMA) and di-n-butyl phthalate, and 1, 4-dioxane as a solvent was used in granulating process, to suppress the residual moisture content in granulated powders and the reaction of alloy powders with its moisture, which result in marked degradation in powder characteristics and magnetic characteristics, respectively. By increasing the additional polymer content, powder characteristics were improved. However in comparison with the case of aqueous binder consisted of poly(vinyl alcohol) (PVA) and plasticizer, powder characteristics lowered slightly because of lower tensile strength of PMMA than PVA. In the case of PMMA the residual moisture contents in granulated powders were much smaller than those of PVA, independently of additional polymer content. The residual oxygen contents of green bodies after debinding were also smaller than those obtained using PVA. By using PMMA the magnetic characteristics (remanences and maximum energy product) of sintered magnets were improved remarkably, as compared with those of PVA. These facts mean that the high magnetic characteristics would be caused by both using low tensile strength polymer and restraining oxidation reaction of alloy powders.抄録全体を表示PDF形式でダウンロード (2120K) -
沈 宝龍, 山崎 徹, 勝部 政弘, 荻野 喜清1998 年 45 巻 4 号 p. 379-384
発行日: 1998/04/15
公開日: 2009/12/04
ジャーナル フリーCu-15.6vol. % Ti(C, N) and Cu-3.1vol. % Ti(C, N) nanocrystalline powders were prepared by ball-milling Cu-l0at. % Ti and Cu-2at. % Ti powder mixtures containing small amounts of stearic acid in nitrogen gas for 200 h. During milling of the Cu-Ti powder mixtures, fcc-Cu phase was refined progressively to average grain sizes of about 20nm in diameter and formation of Ti(C, N) phase was detected by using X-ray diffraction, TEM and ESCA analysis. The milled powders were consolidated by using a HIP process under a pressure of 203 MPa at 1073 K for 2 h. By HIP-consolidating these MA powders, dence nanocrystalline materials of 98.1 and 98.3 % of theoretical bulk densities with average grain sizes of 55nm and 67nm were obtained for Cu-1 5.6vol. % Ti(C, N) and Cu-3.1 vol. % Ti(C, N) materials, respectively. After HIP-processing, the Cu-3. lvol. % Ti(C, N) materials were hot-rolled and subsequently annealed at several temperatures. The density of this material was increased to about 99.7 % by hot-rolling at 873 K, and the nanocrystalline structure having grain sizes between 50 and 100nm with the finely dispersed Ti(C, N). particals and some amounts of graphite particals was observed by HR-TEM. Such a nanocrystalline structure was stable up to the annealing temperature of 1273 K for 5 h.抄録全体を表示PDF形式でダウンロード (2166K)
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