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73 巻, 11 号
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浅井 正, 気賀 智也, 谷口 芳邦, 森川 浩志, 隅山 兼治2009 年 73 巻 11 号 p. 823-832
発行日: 2009年
公開日: 2009/11/01
ジャーナル フリーSn-Ag alloy films, which have been electroplated on thin phosphor bronze plates and annealed at a temperature between 483-523 K, are deterred from tin whisker formation even under a normal mechanical stress. The structure, morphology and chemical analysis studies indicate that large Ag3Sn crystals precipitate and β-Sn(110) planes grow parallel to the film surface. In the as-plated films, Ag3Sn crystals have been already distributed. In annealed films, Ag3Sn crystals increase their sizes to extend from the free surface side to the Sn-Ni interfaces owing to the enhanced diffusion of Ag and Sn atoms at around the eutectic temperature. These characteristic structures and morphologies play key roles to prevent tin whisker formation at ambient temperature probably because they reduce crystal-crystal interfaces, suppress Sn atomic diffusions, decrease the crystal nucleation sites, and release stress and strain retained in as-plated films.
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寺角 隆太郎, 高橋 和枝, 醍醐 市朗, 松野 泰也, 足立 芳寛2009 年 73 巻 11 号 p. 833-838
発行日: 2009年
公開日: 2009/11/01
ジャーナル フリーRecently, material stock accounting has been of interests to investigate the potentials of metal scrap recovery in designated areas. There are two approaches, a top-down approach and a bottom-up approach, for estimating the in-use stock of materials. Top-down approach uses time-series data of consumption and trade of materials and products' life time distributions, whereas bottom-up approach uses the numbers of product units in the designated area and its material use intensities. In this paper, the copper stock in China, Korea and Taiwan were divided into 7 end-uses and estimated by the top-down approach and/or bottom-up approach. The total copper stocks in 2005 were estimated as 25,000 Gg in China, 4,000 Gg in Korea and 2,600 Gg in Taiwan, whereas the ones in 1990 were 4,800 Gg in China, 900 Gg in Korea and 950 Gg in Taiwan. These results show that copper stock in these 3 countries has increased to almost 5 times in the past 15 years.
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小山 真司, 川元 聡2009 年 73 巻 11 号 p. 839-845
発行日: 2009年
公開日: 2009/11/01
ジャーナル フリーThe effect of halogenation treatment with hydrochloric acid on the bond strength of solid-state pressure weld of tin has been investigated by SEM observations of interfacial microstructures and fractured surfaces. The halogenation treatment was carried out by exposing the tin surface (electrolytically polished) to hydrochloric acid vapor for 15 s in a closed container. The solid-state pressure weld was formed in a vacuum chamber at a bonding temperature Tj in the range 323~423 K and at a bonding pressure Pj of 7 MPa (bonding time=1.8 ks). The bond strength of the weld increased with Tj, regardless of the surface treatment. The halogenation treatment decreased the required Tj by 100 K, and the bond strength of the weld was observed to be comparable to that of the base metal. SEM observations of the weld interface revealed the distribution of massive particles that were a few micrometers in size. When Tj increased, the particles coarsened and their number density decreased, resulting in much smaller amounts of inclusions than those observed at the weld interface in the case of tin oxide not subjected to halogenation treatment. In the case of the weld subjected to halogenation treatment, the large area of the weld interface and the very small amounts of inclusions probably contributed to the high bond strength at low bonding temperatures.
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杉浦 隆寛, 西野 洋一2009 年 73 巻 11 号 p. 846-851
発行日: 2009年
公開日: 2009/11/01
ジャーナル フリーWe report on the thermoelectric properties of (Fe2-x-yMy)V1+xAl alloys (M=Ir and Rh) with compositions x=0, 0.02 and 0.05, and y=0-0.10. While a small deviation from the stoichiometric Fe2VAl composition causes an enhancement in the Seebeck coefficient, a slight substitution of Ir or Rh for Fe leads to a further increase in the Seebeck coefficient, reaching -170 μV/K at 300 K for x=0.05 and y=0.03, which is larger than that of the stoichiometric Fe2VAl-based alloys so far reported. Substantial enhancements in the Seebeck coefficient of the off-stoichiometric Fe2VAl-based alloys could be due to a modification in the band structure on the conduction band side around the Fermi level. The doping of heavier atoms such as Ir reduces more effectively the thermal conductivity, while retaining the low electrical resistivity as well as the large Seebeck coefficient, thus resulting in an increased figure of merit of 8.6×10-4 K-1 at 300 K.
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八十 致雄, 林 周平, 森戸 茂一, 大庭 卓也, 久保田 邦親, 村上 浩二2009 年 73 巻 11 号 p. 852-856
発行日: 2009年
公開日: 2009/11/01
ジャーナル フリーIn this paper, the morphologies of martensite and retained austenite for 1.5 mass%C-12 mass% Cr and 1 mass%C-8 mass%Cr steels were observed by means of optical microscopy, XRD, SEM/EBSD and TEM. The amount of retained austenites was quantitatively investigated and compared with XRD, EBSD and TEM observation methods. The retained austenites were distributed in the form of a block type and a film type in the martensite structures. For the 1.5 mass%C-12 mass%Cr steel, the amount of block type retained austenite and film type one are almost equal in three distinct regions of carbide; primary carbide, secondary carbide and without carbide. In the case of 1 mass%C-8 mass%Cr steel, as to film type retained austenite there are not so much differences among those regions. However, block type retained austenites are distributed with much amount, especially in the region around primary carbide.
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杉岡 奈穂子, 北田 正弘2009 年 73 巻 11 号 p. 857-861
発行日: 2009年
公開日: 2009/11/01
ジャーナル フリーThe nanostructure of the orange dye compound Pb2CrO5 in cotton fiber used for touzan fabric imported in the late Edo period has been investigated. Dyed fibers are taken from old touzan fabric. To observe the distribution of nanometer-sized compound grains in the fiber, the cross section of the fiber is flattened by ion milling after mechanical polishing. The nanostructure is observed by SEM and TEM. The composition and crystal structure are analyzed by EDS, XRD and ED. The dye compound Pb2CrO5, is mainly detected by EDS and XRD. Fine acicular precipitates of Pb2CrO5 are aligned along the fiber, forming concentric circles. The Pb2CrO5 crystals have lengths and widths of 50-100 nm and 20-50 nm, respectively. Fine rectangular monoclinic PbCrO4 crystals of 3-5 nm are distributed randomly throughout the fiber. Preferential precipitation is observed at a crack in the fiber, and a precipitation-free zone near the fiber surface is also observed.
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松崎 晃, 名越 正泰, 野呂 寿人, 山下 正明, 原 信義2009 年 73 巻 11 号 p. 862-869
発行日: 2009年
公開日: 2009/11/01
ジャーナル フリーRecently, it has become necessary to improve the corrosion resistance of zinciferous coated steel sheets, especially 55% Al-Zn alloy coated steel sheets. However, it is known that cracks are easily generated on the surface of 55% Al-Zn alloy coated steel sheet during production processes. This is due to the hardness of the metallic coating. We studied non-chromate corrosion-preventive compounds for organic-inorganic composite coatings and found that the composite coating containing both Zn3(PO4)2 and CaSiO3 had the highest corrosion resistance among all the additives tested. The corrosion mechanism was investigated by the analysis of the specimens after corrosion test using SEM, AFM, TEM and EDX. It was found that the amorphous surface layer, which was approximately 30 nm in thickness and contained Ca, Cr, P, Si, C, and O, was newly formed on the steel surface exposed after deformation of the coating. It is presumed that Ca2+ and HPO42- are formed by dissolution of the CaO component in CaSiO3 and hydrolysis of ZnO3(PO4)2, respectively, and they react each other to form an insoluble Ca-phosphoric compound, which might inhibit the corrosion of metals exposed in the cracks.
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中佐 啓治郎, 張 清廉, 王 栄光, 加藤 昌彦2009 年 73 巻 11 号 p. 870-877
発行日: 2009年
公開日: 2009/11/01
ジャーナル フリーThe sputter-etching was carried out on a W-Cr tool steel specimen quenched at 1373 K using argon plasma to form conical or ring-shaped carbide protrusions on the surface. Nano-indentation tests were used to investigate deformation characteristics of the protrusions from load P vs. displacement h curves at maximum loads of 10, 50 and 245 mN. For the surface layer with conical protrusions, the P-h curve at the maximum load of 245 mN is almost similar to that of the specimen without sputter-etching. The reason is explained by a balance of two factors, i.e. the hard carbide layer decreases the deformation during the indentation, while the soft region formed by the depletion of carbide-forming elements under the carbide layer increases the deformation especially after the carbide layer is cracked by the indentation. When the maximum indentation load is 10 mN, the scatter of P-h curves appears reflecting different indentation positions such as the top or side of the protrusions. For a mixture of the thick block-like layers with ring-shaped protrusions and the matrix areas surrounded by them, the maximum displacement and recovery after unloading are both large when the maximum load is 245 mN. The reason will be that the elastic deformation of the thick block-like layers supports the indentation load decreasing the plastic deformation of the soft region under the layers. When the indentation load is 10 mN, the scatter of displacement is very large depending on the indentation either to the protrusions or to the soft matrix region. Tempering after the sputter-etching increases the deformation resistance of the whole layer perhaps due to the precipitation of fine carbides in the soft region under the carbide layer.
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世利 修美, 丹野 聡司2009 年 73 巻 11 号 p. 878-883
発行日: 2009年
公開日: 2009/11/01
ジャーナル フリーBehavior of dry corrosion which is electrochemical reaction between Al-Mg-Si alloy 6063 and ethanol in gasoline has been investigated. Dry corrosion has not been observed in E3 (3% ethanol) and E10 (10% ethanol) at room temperature, but observed in E3 and E10 when a small amount of aluminum chloride had been added to them at room temperature. The higher solution temperature is, the more often the dry corrosion occurs. Dry corrosion has also been observed in the above solution environments in which 0.1% and 1% water contained. Occurrence of dry corrosion was detected by the area polarization method, which revealed that initiation and propagation of the dry corrosion corresponds to the decrease of anodic polarized resistance of 6063.
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本田 和彦, 杉山 昌章, 池松 陽一, 潮田 浩作2009 年 73 巻 11 号 p. 884-889
発行日: 2009年
公開日: 2009/11/01
ジャーナル フリーThe primary Al phase crystallizes preferentially on TiAl3 fine precipitate during the solidification process of hot-dip Zn-11%Al-3%Mg-0.2%Si coating, which leads to the formation of fine dendrite structures by the small amounts of Ti added to the coating bath. TiAl3 is thought to act as heterogeneous nucleation sites of the primary Al phase. Detailed TEM observation of the sectioned specimen by a micro-sampling unit equipped with a FIB system revealed that the TiAl3 fine precipitate is not a single crystal but polycrystals. However, there exists a crystallographic relationship between the TiAl3 phase and the surrounding Al phase, namely, [001]TiAl3//[001]Al, [010]TiAl3//[010]Al and [100]TiAl3//[100]Al. The high-resolution TEM observation of the interface indicates a good coincident relationship between the Al matrix and the precipitate. Therefore, the primary Al phase nucleated heterogeneously on the surface of the TiAl3 phase. Furthermore, the detailed TEM observation revealed a monotectoid reaction by the primary Al phase to the extremely fine Al and Zn phases.
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