巻号一覧
53 巻, 2 号
February
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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研究
受賞記念講演
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桐原 聡秀, 宮本 欽生2006 年 53 巻 2 号 p. 129-135
発行日: 2006年
公開日: 2006/08/04
ジャーナル オープンアクセスThree-dimensional photonic crystals with the periodic variations in dielectric constant were fabricated by using stereolighography of a CAD/CAM process. The millimeter order inverse diamond structures were designed to exhibit forbidden bands in a GHz frequency range. Air spheres were arranged periodically in epoxy bulks containing titania-silica particles with high dielectric constant. The attenuation of transmission amplitude of microwave was measured by using horn antennas and network analyzer. The samples exhibited a common energy gap for Γ-X <100>, Γ-K <110>, Γ-L <111> directions in the microwave band of 9.2-10.8 GHz. The obtained results fairly agreed with the theoretical simulation of the electromagnetic wave propagation through photonic crystals. This result suggests the complete band gap formation in all directions. Alumina spheres were implanted into air gaps of crystal samples as structural defects. Localized modes were formed at the resonant frequency of the dielectric defects in the band gap.抄録全体を表示PDF形式でダウンロード (1109K)
研究
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柴田 英明, 鎌倉 光利2006 年 53 巻 2 号 p. 136-142
発行日: 2006年
公開日: 2006/08/04
ジャーナル オープンアクセスThe most difficult task of fabrication of ceramics-metal functionally gradient materials (FGMs) by the powder molding method is to simultaneously sinter two materials with largely different sintering temperature. In this work, the mixed powders of Ti and C and Ti and B were laminated with gradually changing composition, and then sintered using self-propagating high-temperature synthesis (SHS). It was found that TiC/Ti and TiB2/Ti FGMs with high hardness could be fabricated from two kinds of the mixed powders at the lower sintering temperature than that of monolithic TiC and TiB2. Two kinds of FGMs were fabricated by spark plasma sintering(SPS) and pressureless sintering.抄録全体を表示PDF形式でダウンロード (1469K) -
Takashi Yoshioka, Yukio Makino, Shoji Miyake2006 年 53 巻 2 号 p. 143-148
発行日: 2006年
公開日: 2006/08/04
ジャーナル オープンアクセスAluminum nitride with oxide additive of CaO-Al2O3-Yb2O3 system was synthesized by 28GHz millimeter-wave heating method. Densification over 95%TD (TD: theoretical density) and thermal conductivity close to 150W/(m·K) were attained at a low temperature of 1500°C for 120min. The lowering of densification temperature was attributed to the predominantly heating of Yb2O3 in additive oxide, which arises from the effective absorption of millimeter-wave into Yb2O3. The successful synthesis of AlN with fairly high thermal conductivity at 1500°C is suggested to be available for an economical manufacturing of AlN.抄録全体を表示PDF形式でダウンロード (962K)
特集：硬質材料およびその応用
総報
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林 宏爾2006 年 53 巻 2 号 p. 151-153
発行日: 2006年
公開日: 2006/08/04
ジャーナル オープンアクセスA NEDO project proposed by JRCM and AIST aims at the integrated development of materials and mold processing technologies for high-precision micro-components through unified promotion of three themes: (I) Development of Novel Metals with High Formability, (II) Development of Materials and Processing Technologies for High-precision Mold, and (III) Development of High-precision Forming Technology. In this paper, the necessity of the development of finer submicro-grained WC-Co hardmetal than the present commercial ones is described.抄録全体を表示PDF形式でダウンロード (493K)
研究
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水上 正彦, 山本 良治, 浅田 信昭, 松本 明英2006 年 53 巻 2 号 p. 154-159
発行日: 2006年
公開日: 2006/08/04
ジャーナル オープンアクセスNano-sized WC powder that is expected as the raw material for nano-sized WC-Co hardmetals with high hardness and strength was developed. The reaction path and morphological change in the reaction process of WO3 with carbon powder (direct carburization) were firstly investigated by thermogravimetric analysis. The proper reaction condition examined by the thermogravimetric analysis was developed to trial production by direct carburization facilities.
The direct carburization reaction from WO3 to WC occurred through the generation of several intermediate products in the order of WO3 → WO2.72 → WO2 → W → W2C → WC. The nano-sized particles were generated at the stage from WO2.72 to WO2. We succeeded in the development of nano-sized WC powder less than 100 nm by controlling the reaction conditions for each intermediate products.抄録全体を表示PDF形式でダウンロード (1085K) -
松野 恭司, 川上 優, 寺田 修, 林 宏爾2006 年 53 巻 2 号 p. 160-165
発行日: 2006年
公開日: 2006/08/04
ジャーナル オープンアクセスThe microstructure and properties of WC-0.9mass%Cr3C2-0.5mass%VC-10mass%Co submicro-grained hardmetal sintered compacts which were prepared by hybrid sintering (a combination method of directly electrifying hot-press sintering with normal sintering, i.e., externally heating pressureless sintering) and normal sintering were investigated. It was found that the lowest sintering temperature for almost full density (≥99% of theoretical density) in hybrid sintering was lower by 30 K than that in normal sintering. The mean grain size of WC in the alloy with almost full density, however, was nearly the same of 0.16 μm for both sinterings. The hardness of the highest value was almost the same of 2170 HV for both sinterings. Thus, it was concluded that hybrid sintering has no merits as far as in grain size and hardness, compared with normal sintering.抄録全体を表示PDF形式でダウンロード (1841K) -
Masaru Kawakami, Osamu Terada, Koji Hayashi2006 年 53 巻 2 号 p. 166-171
発行日: 2006年
公開日: 2006/08/04
ジャーナル オープンアクセスHRTEM (high resolution transmission electron microscope) microstructure and the segregation amount of dopants at WC/Co interfaces were investigated on TiC and TaC mono-doped WC-10mass%Co submicro-grained hardmetals, following the previous studies on VC, Cr3C2 and VC+Cr3C2 doped hardmetals. The dopant amounts in the specimen were nearly a half of the solubility limit in Co liquid phase. At WC(0001)/Co interface, Ti segregated in a small amount and Ta hardly segregated. At WC(1010)/Co interface, both Ti and Ta hardly segregated. The order of segregation amounts (at% of metal of carbide or mol% of carbide) of dopants at WC(0001)/Co interface (TaC<TiC<Cr3C2<VC≤VC+Cr3C2) were not necessarily positively correlated with the magnitude of grain growth inhibition effect (TiC<Cr3C2<TaC<VC≤VC+Cr3C2). This suggested that the segregation layers of dopants themselves were not directly related with WC grain growth inhibition mechanism and that the layer was not generated by an equilibrium segregation mechanism during the sintering stage, but by a heterogeneous precipitation mechanism during the cooling stage of sintering.抄録全体を表示PDF形式でダウンロード (1109K) -
佐々木 章, 竹内 文浩, 川上 優, 伊藤 博郎, 寺田 修, 林 宏爾2006 年 53 巻 2 号 p. 172-176
発行日: 2006年
公開日: 2006/08/04
ジャーナル オープンアクセスThe conditions for the generation of Co rich layer on the surface of sintered compact of WC-Co submicro-grained hardmetals doped with VC and Cr3C2 were investigated. The following were found: (1) At a normal conditions (1563K-3.6ks, 0.07K/s), there were two kinds, i.e., granular and flat Co rich layers, and these layers were generated at medium sintering temperature, and at any C, VC, Cr3C2 and Co contents, and (2) the granular and flat layer were not generated at higher sintering temperature and at higher cooling rate of sintering, respectively, for all kind alloys. Namely, two kinds of Co rich layers were not generated, when the alloy compacts were sintered at high temperature and then rapidly cooled.抄録全体を表示PDF形式でダウンロード (1764K) -
佐野 勝健, 西嶋 守男, 前嶋 康宏2006 年 53 巻 2 号 p. 177-182
発行日: 2006年
公開日: 2006/08/04
ジャーナル オープンアクセスIn the fabrications of the next generation inkjet nozzle and optical fiber connector with higher precision than the present one (±0.5μm), the development of high precision mold by WC-Co submicro-grained hardmetal is strongly demanded, because the hardmetal has higher wear resistance, higher fracture strength, etc., together with high rigidity. We are trying to establish the manufacturing technology of such molds with precision of ±0.3μm (the interim goal) and ±0.1μm (the final goal) by using micro-electric discharge machining and centerless grinding.
The surface roughness of rectangular alloy body that was electric discharge machined and than lapped became finer with decreasing WC grain size from ±2.5μm to ±0.5μm.
In the jogging processing by centerless grinding machining of core pin with three-stepped diameters of φ250, 125 and 80μm, the accuracy of ±0.15μm exceeding the interim goal was achieved for submaicro-grained hardmetal with ±0.5μm.抄録全体を表示PDF形式でダウンロード (1118K) -
高尾 佳宏, 金井 巨光2006 年 53 巻 2 号 p. 183-186
発行日: 2006年
公開日: 2006/08/04
ジャーナル オープンアクセスThis paper reports the results on the V shape ditch processing that is expected to be applied to a die for light parts, where submicro-grinded hardmetal was used as the material for the die.抄録全体を表示PDF形式でダウンロード (647K) -
細川 裕之, 中嶋 剛, 下島 康嗣2006 年 53 巻 2 号 p. 187-191
発行日: 2006年
公開日: 2006/08/04
ジャーナル オープンアクセスWC-Co alloys with WC grain sizes from 0.4 to 4.5 μm and the Co contents of 10 and 15 mass% were machined by focused ion beam (FIB) of 30 keV Ga+ and their surface roughness was investigated, where beam diameters are 100 nm and 300 nm, the beam overlap is 50 %, the pixel dwell times are 100 and 227μs and beam incident angles are from 0° to 50° degrees. Experimental results from the viewpoint of effect of microstructure showed that the surface roughness depended on width of Co phase. Moreover, it was revealed on the effect of machining conditions that small surface irregularities was obtained under the condition of larger beam diameter, shorter dwell time and higher beam incident angle in this work.抄録全体を表示PDF形式でダウンロード (1102K) -
波形 英樹, 北村 哲弥, 青木 彦治, 伊藤 敦, 中本 光2006 年 53 巻 2 号 p. 192-196
発行日: 2006年
公開日: 2006/08/04
ジャーナル オープンアクセスMicro press dies coated with DLC that has excellent performance for wear and friction have been expected for press processes. However, improvement of the adhesion of DLC coating is especially to apply to strong plasticity processing. There is the weak point that the adhesion of DLC coating is low, because high compression stress remains in the DLC coating inside. Therefore, we examined possibility to improve the adhesion of DLC coating by optimization of the DLC coating condition. In addition, we suggested that we made micro size dimples on DLC coating surface and examined possibility to improve tribology characteristics by maintaining lubricant in the dimples.抄録全体を表示PDF形式でダウンロード (467K) -
仲 恭宏, 繁松 孝, 東藤 慎平2006 年 53 巻 2 号 p. 197-201
発行日: 2006年
公開日: 2006/08/04
ジャーナル オープンアクセスSimulation technology was developed for high precision molding of optical fiber connectors. Two simulation models regarding resign flow performance in the mold cavity were constructed and calculated. One is the calculation on resign flow performance around micro pins arrayed in the mold cavity. Prediction of the force to pins and their bending trend was made possible. Flow rate and cure extent of resign are affecting factors, and optimum flow rate is expected. Another is the calculation on resign flow performance including filler particles. Prediction of the particle distribution around micro pins was made possible. Larger particles are not tend to run behind micro pins, and non-uniform transcription properties is predicted.抄録全体を表示PDF形式でダウンロード (929K)
受賞記念講演
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阪上 楠彦, 山本 勉2006 年 53 巻 2 号 p. 202-207
発行日: 2006年
公開日: 2006/08/04
ジャーナル オープンアクセスBending and compressive fatigue characteristics of WC-Co alloys were mainly investigated and discussed relating to structural defects, surface residual stress or coercive force in the alloy. The bending fatigue was influenced by the structural defects such as pore, WC and Co pool acting as a fatigue fracture origin. Especially, the fracture origin of Co pool with a step shaped form peculiar to the bending fatigue was often observed in HIP-treated alloys. Therefore, the fatigue life in micro-grain alloy was improved with the decrease of Co pool size. As to the effect of surface condition, the fatigue life was remarkably influenced by compressive residual stress of the ground surface rather than surface roughness, while the decrease of the fatigue life by coating treatment could be explained by residual stress of the coated layer and base alloy or adhesion between them. On the other hand, the compressive fatigue was not influenced by the structural defects, but it showed a positive correlation with the variation of the coercive force influenced by fatigue hardening in Co phase. Namely, the coercive force of the medium-grain alloy increased with increasing applied stress and repeated cycle, and it became much larger in the repeated compressive fatigue test than static compressive test.抄録全体を表示PDF形式でダウンロード (704K)
研究
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Kusuhiko Sakagami, Shinichi Kouno, Tsutomu Yamamoto, Kazuhiko Majima2006 年 53 巻 2 号 p. 208-213
発行日: 2006年
公開日: 2006/08/04
ジャーナル オープンアクセスWC-βt-Co alloys have been widely applied to cutting tools because they are superior to WC-Co alloys in oxidation, plastic deformation and adhesion resistances. In this study, the effects of HIP treatment, WC grain size and content of βt phase on bending fatigue characteristics were investigated for fine and coarse-grained WC-6.7mass%βt-10.4mass%Co alloys (6.7βt(F) and 6.7βt(C) alloys) and fine-grained WC-20mass%βt-11.3mass%Co alloy (20βt(F) alloy) by comparing with the case of fine-grained WC-10mass%Co alloy(10Co(F) alloy) without βt phase.
The results obtained were as follows: (1) The bending fatigue life of HIP-ed 6.7βt(F) alloy was longer than that of normally sintered 6.7βt(F) alloy. The S-N curve of HIP-ed alloy showed a small gradient in a high stress range and a large gradient in a low stress range. (2) The fatigue life of HIP-ed 6.7βt(F) alloy remarkably decreased in the high stress range, but slightly decreased in the low stress range, compared with that of 10Co(F) alloy. (3) The fatigue life of HIP-ed 6.7βt(C) alloy was superior in all the stress range, compared with that of HIP-ed 6.7βt(F) alloy. (4) The fatigue life of HIP-ed 20βt(F) alloy was shorter than that of 6.7βt(F) alloy in all the stress range. The above-mentioned results were mainly discussed relating to the fatigue fracture origins such as pore, Co pool, aggregate of βt grains, etc.抄録全体を表示PDF形式でダウンロード (2299K) -
岩永 健吾, 平田 浩郎, 山崎 裕司, 井上 勝, 高木 研一2006 年 53 巻 2 号 p. 214-220
発行日: 2006年
公開日: 2006/08/04
ジャーナル オープンアクセスTo apply to plastic injection molding parts, the effects of Cr and Mo contents on mechanical properties and corrosion resistance in a molten fluoropolymer were studied in two series of Mo2NiB2 base cermets with the composition of Ni-5.0mass%B-Xmass%Cr-51.0mass%Mo (X: 12.5∼20.0) and Ni-5.0mass%B-15.0mass%Cr-Ymass%Mo (Y: 46.6∼55.4 (Mo/B atomic ratio: 1.05∼1.25)).
In Ni-5.0mass%B-Xmass%Cr-51.0mass%Mo cermets, transverse rupture strength (TRS) increased with increasing Cr content and showed a maximum value of 2.2GPa at 17.5mass%Cr, and then decreased at 20.0mass%Cr. Hardness increased monotonically with increasing Cr content and showed a maximum value of 86.5HRA at 20.0mass%Cr. In Ni-5.0mass%B-15.0mass%Cr-Ymass%Mo cermets, TRS increased with increasing Mo content and showed a maximum value of 2.3GPa at 53.2mass%Mo (Mo/B atomic ratio: 1.20), and then decreased at 55.4mass%Mo (Mo/B atomic ratio: 1.25). Hardness increased monotonically with increasing Mo content and showed a maximum value of 87.5HRA at 55.4mass%Mo. In both series of cermets, improvements of TRS and hardness were mainly attributed to refinement of tetragonal M3B2 (M: Mo, Ni, Cr) complex boride particles. Lowering of TRS seems to be due to embrittlement caused by aggregation of tetragonal M3B2 complex boride particles and precipitation of tetragonal M5B3 complex boride particles.
The excellent corrosion resistance equivalent to Hastelloy C in a molten fluoropolymer was obtained in Ni-5.0mass%B-15.0∼17.5mass%Cr-51.0mass%Mo and Ni-5.0mass%B-15.0mass%Cr-48.8∼53.2mass%Mo (Mo/B atomic ratio: 1.10∼1.20) cermets.抄録全体を表示PDF形式でダウンロード (1188K)
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