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72 巻, 7 号
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北田 正弘, 張 大石2008 年 72 巻 7 号 p. 483-490
発行日: 2008年
公開日: 2008/07/01
ジャーナル フリーThe microstructures and impurities of cobalt blue enamel used in the first Imari porcelain made in the early 17th century have been investigated. The fine structures are observed using a transmission electron microscope. The elements in the enamel are analyzed by EDX. A fine acicular crystal and a nanometer-sized circular precipitate are observed in the blue enamel. The acicular crystal contains 76 mol% Si, 16 mol% Al, 4.8 mol% Ca and small amounts of Na and K. The sizes of the crystals are 0.2-0.5 μm width and 0.5-5 μm length. The circular precipitates are 20-80 nm in diameter, contain Co species, and the structure is amorphous. The main constituents of the circular precipitate are 66 mol% Si, 9-10 mol% Al and Ca, and 1-4 mol% Na, Mg, and P. Furthermore, small amounts of Mn and Fe are detected. The concentration of Co in the circular precipitate is 0.7~1.4 mol% (average: about 1 mol%). The average concentration of the amorphous matrix is 97 mol% Si, and small amounts of Al, Ca, Na, and other trace elements are detected. From the analysis of the fine structures, the acicular crystals are found to precipitate primarily, and then the amorphous circular precipitates are separated from the amorphous matrix. In the transparent enamel used in Imari porcelain, fine crystals are distributed in an amorphous matrix. Their size is 20-80 nm in width and 50-600 nm in length. The composition of the crystal is approximately Si3Al2O7.5 and that of the amorphous matrix is Si1.0Al0.025O1.5.
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小口 かなえ, 鈴木 俊夫2008 年 72 巻 7 号 p. 491-495
発行日: 2008年
公開日: 2008/07/01
ジャーナル フリーComputational efficiencies and accuracies in various phase-field models were investigated: a phase-field model with the anti-trapping current method, a phase-field model with the reduced interface method and a standard phase-field model. Dependence of the mesh size on the growth velocity of a dendrite was examined. In the case of the low undercooling, the anti-trapping current method gave the most accurate result within 4% error reducing the calculation time by about 25% when the size of meshes was doubled. On the other hand, the reduced interface method gave the most accurate result within 5% error reducing the calculation time by about 25% with the doubled size of the meshes in the case of the high undercooling.
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福井 泰好, 岡田 裕, 熊澤 典良, 渡辺 義見2008 年 72 巻 7 号 p. 496-502
発行日: 2008年
公開日: 2008/07/01
ジャーナル フリーWear properties of Al-Al3Ni functionally graded material (FGM) manufactured by a vacuum centrifugal method were measured to evaluate the effect of semi-solid forming. Semi-solid forming varies the coarse Al3Ni particles in an Al-Al3Ni FGM into finer ones. The evaluation of the wear properties is an important subject to utilize the Al base FGM as component and structural material. Thus, the dry wear characteristics of Al-Al3Ni FGM were examined by using block-on-ring type test apparatus. The variations of the friction force, the wear rate and the temperature rise with the sliding distance were experimentally measured and the relations among them were clarified. Both the friction coefficient and temperature rise of semi-solid forming specimens were smaller than those of original ones. Moreover, the sizes of wear particles in case of semi-solid forming specimen were finer than those of original ones. The possible reason for this change in the nature of debris is that the semi-solid forming introduces the finer structure and then finer structure brings better wear properties.
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金高 弘恭, 清水 良央, 細田 秀樹, 冨塚 亮, 鈴木 章裕, 浦山 佐知子, 稲邑 朋也, 宮崎 修一, 山本 照子2008 年 72 巻 7 号 p. 503-509
発行日: 2008年
公開日: 2008/07/01
ジャーナル フリーThe purpose of this study was to evaluate the performance and the usefulness of a newly developed Ni-free Ti-based shape memory alloy (SMA) wire in orthodontic tooth movement by comparing with a nickel-titanium (Ni-Ti) alloy wire. A titanium-niobium-aluminum (Ti-24Nb-3Al) SMA wire, which was considered to be biocompatible because it contained no nickel, was newly developed and mechanical property of this new alloy was improved by severe cold rolling reduction. Twenty-one male Wistar-strain rats (age; 6 weeks) were used in the animal experiment. A Ti-Nb-Al alloy wire and an orthodontic superelastic wire (Ni-Ti alloy wire) were set in the oral cavities of rats, and orthodontic palatal movement of maxillary first molars was performed with an initial load of 15 gf. The amount of tooth movement was measured and periodontal structures were histologically examined. The Ti-Nb-Al alloy wire was effective for palatal tooth movement without any adverse reaction in rats. There was no significant difference in the amount of tooth movement between the Ti-Nb-Al group and the Ni-Ti group. Histological observation of the periodontal tissues revealed no differences between the two groups. These results indicate that Ti-Nb-Al alloy wire has excellent mechanical properties suitable for orthodontic tooth movement, suggesting that Ti-Nb-Al wire may be used as a practical nickel-free shape memory and superelastic alloy wire for orthodontic treatment as a substitute for Ni-Ti alloy wire.
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末永 竜一, 嶋崎 哲也, 久保 大司, 神田 昌枝, 中野 良, 松村 義人, 西 義武2008 年 72 巻 7 号 p. 510-514
発行日: 2008年
公開日: 2008/07/01
ジャーナル フリーMagnetostriction and its susceptibility of Fe3.2Tb alloy thin film deposited on polyurethane rubber substrate with low deformation resistance by using direct current magnetron sputtering process were investigated. When both residual gas pressure before argon sputtering and sputtering pressure of argon gas (5 N) were less than 5.0×10-4 Pa and 2.0×10-1 Pa, respectively, the thickness of the Fe3.2Tb films deposited was about 2.96 μm. The giant magnetostriction was found in the Fe3.2Tb alloy film on polyurethane rubber sheet, rather than on other polymer sheets. Giant motion strain of Fe3.2Tb alloy film largely depended on deformation resistance of substrate.
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久保 大司, 森田 崇志, 及川 奨, 内田 晴久, 西 義武2008 年 72 巻 7 号 p. 515-519
発行日: 2008年
公開日: 2008/07/01
ジャーナル フリーHydrogenation operates the bending motion of mover device, which is a platinum coated La-Ni alloy film deposited on a polyimide sheet, has been successfully developed. Influence of the operating temperature on the motion strain has been evaluated. When the operating temperature is 373 K, the maximum value of bending strain (Δε) is 408 ppm, which is 1.4 times larger than that (300 ppm) of an unheated film operated at 323 K.
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佐藤 浩則, 井上 祐大, 岩田 圭祐, 利根川 昭, 西 義武2008 年 72 巻 7 号 p. 520-525
発行日: 2008年
公開日: 2008/07/01
ジャーナル フリーInfluence of electron beam (EB) irradiation on the impact value of Acryl resin was studied. EB irradiation of less than 10.8 kJ kg-1 (kGy) apparently increased the impact value. EB irradiation from 10.8 to 21.6 kJ kg-1 (kGy) decreased the impact value, although it was larger than that of the untreated sample. The impact value enhancement by EB irradiation was explained by increasing the bending strength.
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佐藤 浩則, 岩田 圭祐, 利根川 昭, 西 義武2008 年 72 巻 7 号 p. 526-531
発行日: 2008年
公開日: 2008/07/01
ジャーナル フリーJoining between Nylon-film and Silicone-rubber was successfully developed by using homogeneous EB irradiation. Effects of electron beam (EB) irradiation on joining strength of different polymers without adhesive materials were investigated. Although excess EB-irradiation more than 300 kJ kg-1(kGy) apparently decreased the joining strength, the EB irradiation increased the joining strength of the joining sample between Nylon-film and Silicone-rubber. To discuss the influences of EB irradiation on the joining strength, electron spin resonance (ESR) signals related to dangling bonds were observed. Since EB irradiation generated dangling bonds on Nylon-film, dangling bonds probably supported the each other polymer at interface.
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佐藤 嘉, 野村 直之, 藤沼 重雄, 千葉 晶彦2008 年 72 巻 7 号 p. 532-537
発行日: 2008年
公開日: 2008/07/01
ジャーナル フリーThe gas atomized Co-29Cr-6Mo alloy powder was hot-pressed at various temperatures from 1223 K to 1357 K with applied pressures of 50 or 80 MPa for 7.2 ks. Mean grain size of the compacts hot-pressed at 1257 K is 2.7 μm and the relative density is 97%. The grain size of the compacts tends to increase with increasing sintering temperature. The σ phase is observed in the compacts hot-pressed at 1223 K to 1307 K.
The ultimate tensile strength of the compacts hot-pressed at 1257 K and 80 MPa shows the highest value (1240 MPa) in the compacts due to the fine grain size (2.7 μm). Meanwhile, the compact hot-pressed at 1357 K and 50 MPa shows the highest plastic elongation (50%). This is attributed to the facts that the σ phase is dissolved in the fcc matrix during hot-pressing at 1357 K and strain-induced martensite transformation (SIMT) proceeds during plastic deformation. These values are much higher than those of as-cast Co-29Cr-6Mo alloy and comparable to those of the forged Co-29Cr-6Mo alloy.
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山本 尚嗣, 廖 金孫, 中田 一博2008 年 72 巻 7 号 p. 538-543
発行日: 2008年
公開日: 2008/07/01
ジャーナル フリーFriction stir weldability of a fine-grained high tensile strength Mg-Zn-Al-Ca-La magnesium alloy was evaluated by changing joining parameters, such as tool rotating speed and welding speed. Square butt joints with good quality were obtained at the conditions of welding speed 250-600 mm/min and tool rotating speed 16.7-25 s-1, by using a tool with shoulder diameter of 15 mm, pin diameter of 5 mm and pin length of 3.9 mm. Higher welding speed or rotating speed led to the lack of bonding in the joint. Hardness at the center region of stir zone was slightly higher than that of the base metal, but hardness at the other region was slightly lower. It can be believed that the hardness of stir zone depends on the distribution and size of the inter-metallic compounds as well as the grain size of the recrystallized structure. Transverse tensile strength of friction stir welded joint was about 335 MPa, lower than that of the base metal (about 367 MPa). It was considered that the tensile strength of friction stir welded joint of Mg-Zn-Al-Ca-La magnesium alloy was strongly influenced by both the crystallographic orientation distribution and grain size.
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