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74 巻, 1 号
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安田 幸司, 岡部 徹2010 年 74 巻 1 号 p. 1-9
発行日: 2010年
公開日: 2010/01/01
ジャーナル フリーHigh purity silicon used for photovoltaic application, namely solar grade silicon (SOG-Si), has been commercially supplied mainly from the off-grade high purity silicon manufactured by the Siemens process. However, recent and rapid growth in solar cell production induces a serious shortage of SOG-Si. With an aim of resolving low productivity of the Siemens process, various types of SOG-Si production/purification processes have been invented as a post-Siemens process. Some processes are currently under development aiming at establishment of commercial process. These processes can be classified into the following three technologies: (1) decomposition and/or hydrogen reduction of silane gases by improving the current commercial Siemens-based processes, (2) metallothermic reduction of silicon halide compounds by zinc or aluminum, and (3) upgrading metallurgical-grade silicon by employing metallurgical purification methods.
This paper reviews the features of the SOG-Si production processes, particularly the processes based on the metallothermic reduction. These metallothermic reduction processes are classified from the viewpoint of the reductant types and silicon compounds. The future prospect for the development of new high purity silicon production process is presented.
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論文
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土井 教史, 来村 和潔, 中西 康次, 鹿島 和幸, 上村 隆之, 幸 英昭, 太田 俊明, 山下 正人2010 年 74 巻 1 号 p. 10-18
発行日: 2010年
公開日: 2010/01/01
ジャーナル フリーAl-bearing steels showed high corrosion resistance into coastal environments. The layer of the rusts containing Al was formed on the surface of those alloys after long periods of exposure to the coastal environments, and it was suggested that the Al plays an important role in the corrosion resistivity. In this work, we applied X-ray diffraction, electron microscopy, Raman scattering and X-ray absorption near edge structure measurements for investigating the state of Al in the rust layer. It was found that the increase in the Al content of those alloys increased amorphous and goethite type iron oxide in the rust. The Al-K XANES spectra indicated that the Al substituted goethite, α-Fe1-xAlxOOH, formed on those alloys. This action of Al has an effect on the properties of rust and serves to increase the protective ability of rust layer.
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笠井 一輝, 村上 秀之, 黒田 聖治, 今井 八郎2010 年 74 巻 1 号 p. 19-23
発行日: 2010年
公開日: 2010/01/01
ジャーナル フリーThe effect of pre-surface treatment and crystal orientation on microstructural changes in the aluminized 4th generation Ni-based single-crystal superalloy TMS-138 was investigated. The substrate superalloy was cut along the {100} and {110} planes on which three kinds of surface finishing, such as grit-blasting, mechanically polishing and electro-polishing were conducted prior to the conventional high-activity aluminizing process. A thermal cycling test at 1373 K revealed that heavy deformation of substrate surface by grit blasting gave rise to the formation of a secondary reaction zone (SRZ) in the vicinity of interdiffusion zone/substrate interfaces. While when the surfaces were finished by electro-polishing, voids were formed in the vicinity of interdiffusion zone/substrate interfaces. It is also found that accelerated formation of SRZ and voids was observed along <110> directions rather than <100> directions during the thermal cycling test. The difference in morphological changes of substrates can be related to the residual stress introduced by the surface finishing.
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松尾 孟, 海江田 裕介, 児嶋 伸浩, 池田 賢一, 波多 聰, 中島 英治2010 年 74 巻 1 号 p. 24-29
発行日: 2010年
公開日: 2010/01/01
ジャーナル フリーThis paper reports the mechanical property and crack propagation behavior of thin ceramics. A method to evaluate the stress intensity factor, KI, of thin ceramics was proposed. Dependence of KI values on the average grain size, d, of thin α-alumina were measured by the method. KI values of thin α-alumina decreased with increasing d values from 4.3 μm to 15.2 μm, while the KI values were almost constant for 15.2 μm≤d≤63.0 μm. The trend of KI values agreed with the dependence of fracture toughness, Kc, of bulk α-alumina. The thin α-alumina specimens after crack propagation were investigated by scanning electron microscopic electron back-scattered diffraction (SEM/EBSD) analysis. Branched cracks were hardly observed, regardless of grain size. The result indicates that the toughing mechanism do not occur in the thin α-alumina. Dependence of the transgranular fracture rate, F, and the crack deflection rate, D, on d were measured from the orientation distribution maps. However, the F values and the D values were independent of d and approximately constant. The F values and D values depend on d in bulk α-alumina. It indicates that the crack propagation behavior is varied by thinning α-alumina.
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崔 禎恩, 北田 正弘2010 年 74 巻 1 号 p. 30-35
発行日: 2010年
公開日: 2010/01/01
ジャーナル フリーThe microstructure of the bronze coin, Headongtongbo, circulated around 1097 and fabricated in the Korai period (10~14th centuries) has been investigated. The coin is 23.4 mm in diameter and 1.7 mm in thickness with weight of 4.75 g. Transmission electron microscope, X-ray diffraction, scanning electron microscope, and electron dispersive X-ray analyses are used to determine the structure of the specimen. The composition of the specimen is Cu-6.1 mass%Sn-1.4 mass%Pb-0.5 mass%S. αCu, Pb and Cu2S grains are observed using an optical microscope. The Cu2S phase has been observed in a Korai bronze mirror, as reported in the previous paper. The αCu phase shows a recrystallized polygonal structure. In some part of the αCu grains, twins and fine twinlike lines are observed. Cu2S particles are dispersed in αCu grains and the grain boundary. In αCu grains near the surface, grain boundaries and the twin boundary are corroded preferentially. The Cu2S grains retain their original shape and remain in the corroded layer. αCu corrodes from Cu2O to CuO, and then to Cu2CO3(OH)2.
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大堀 鉄太郎, 白幡 淳, 浅見 廣樹, 鈴木 常生, 中山 忠親, 末松 久幸, 新原 晧一2010 年 74 巻 1 号 p. 36-41
発行日: 2010年
公開日: 2010/01/01
ジャーナル フリーCompositionally gradient boron nitride with silicon (BN:Si) thin films have been prepared on silicon (100) substrates by radio frequency magnetron sputtering. A hexagonal boron nitride (h-BN) target with uneven distribution of silicon plates was used for the deposition. The present study was focused on the investigation of the morphology, the microstructure, the determination of silicon composition, the bonding structure and the micro-hardness using scanning electron microscopy (SEM), Rutherford back scattering spectroscopy (RBS), Fourier transform infra-red spectroscopy (FT-IR) and micro-hardness testing with a Vickers indenter. The BN:Si thin films with the thicknesses of 100~850 nm were not peeled off as compared to the boron nitride thin films with the same thicknesses. Increasing the Si content of the boron nitride thin films induced a decrease in fraction of sp3 bonding. The cubic boron nitride (c-BN) thin film with silicon addition was deposited with a thickness of 850 nm at 5.2 mol% silicon content. On the other hand, the hardness was 72 GPa and the young's modulus was 286 GPa. Since the c-BN:Si thin film was peeled off from silicon substrate at a few weeks after the deposition, compressive stress was not completely released by silicon addition.
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山浦 真一, 井上 明久2010 年 74 巻 1 号 p. 42-48
発行日: 2010年
公開日: 2010/01/01
ジャーナル フリーThe effect of surface coating element on hydrogen absorption and permeation of the (Ni0.6Nb0.4)70Zr30 amorphous alloy membrane was investigated. As a result, it was found that the Ni-coated sample exhibited a much slower hydrogen absorption rate than the Pd-coated sample. However, both types of sample showed same hydrogen absorption content after saturation. The Pd-coated sample showed hydrogen permeation one order of magnitude larger than Ni-coated sample. The pressure dependence of permeation flux was also investigated and it was found that the rate controlling factor of hydrogen permeation in the Pd-coated sample and in the Ni-coated sample was hydrogen diffusion in the alloy and surface reaction, respectively. It was also found that the permeability of the samples with Ni and Pd on the upper-side (retentate side) and the lower-side (permeate side) surfaces, respectively, was smaller than that of the Pd-coated samples, comparing those two types of the sample having the Pd coating layer on the lower-side surface of the membrane. This is because the hydrogen concentration gradient in the sample with Ni and Pd on the upper-side and the lower-side surfaces, respectively, is smaller than that in the Pd-coated sample due to the smaller solubility of hydrogen in the Ni coating layer than in the Pd coating layer. Furthermore, it was found that the element deposited on the lower-side surface of the membrane affected the promotion of hydrogen permeation more significantly than that on the upper-side surface. In this study, the hydrogen permeation of the sample with Ni coated on the lower-side surface of the membrane was much smaller than that with Pd on the lower-side surface. This observation suggests that the recombination of two H atoms and emission of H2 molecules from the lower-side surface can be the significant barrier to hydrogen permeation. Therefore, it was concluded that the hydrogen concentration gradient in the matrix membrane and the reaction on the lower-side surface affected the hydrogen permeability of the membrane sample.
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青山 正義, 浦尾 亮一2010 年 74 巻 1 号 p. 49-54
発行日: 2010年
公開日: 2010/01/01
ジャーナル フリーThe effects of grain size and Sn concentration on the bending fatigue life of Cu-Sn alloy were studied. Both the bending fatigue test and tensile test were conducted by using a Cu-Sn alloy under 2.0 mass%Sn with grain size being controlled by annealing. We found that the smaller the grain size, the longer the bending fatigue life of the Cu-Sn alloy and the higher the Sn concentration in copper. A Long bending fatigue life for the Cu-Sn alloy obtained by increasing of 0.2%Proof Stress involves three stress-dependent factors: grain size, friction stress and Hall-Petch constant. Friction stress and the Hall-Petch constant are functions of the Sn concentration in copper. Dislocation structures were found in cell structures after the bending fatigue test observed in Oxygen-free, high-conductivity copper, while the Cu-Sn alloy revealed a uniform distribution structure of dislocation.
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山村 興司, 川田 直之, 西原 公2010 年 74 巻 1 号 p. 55-60
発行日: 2010年
公開日: 2010/01/01
ジャーナル フリーFriction stir welding (FSW) has been receiving considerable attention along with friction stir processing (FSP), which is a new technique based on the principles of FSW. In a recent study by the author, the excellent fluidity of aluminum alloy in FSP was recognized, and metal matrix composites (MMCs) were fabricated by the local dispersion of aluminum oxide particulates in aluminum alloy. In the present study, we propose novel methods for property modification of MMCs, such as the fabrication of local metallic foam of 6061 aluminum alloy by FSP. First, titanium hydride particles (TiH2) were dispersed locally as a foaming material to produce the local MMC. Then, the specimen was heated in an electric oven for local foaming. As a result, the structure of the foam produced in the layers was controlled by the titanium hydride particles dispersed in those layers.
By monitoring the heat generated during FSP, we investigated the possibilities of dispersing the foaming material by the heat generating in FSP without the application of additional heat using an electric oven. The result showed that the possibility of local foaming by the heat generated in FSP. However, there are still problems for solution like the control of the maximum heating temperature, and future tasks.
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寄書
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明日香 壽川, 山本 政一郎, 朝山 慎一郎2010 年 74 巻 1 号 p. 61-63
発行日: 2010年
公開日: 2010/01/01
ジャーナル フリーEndo et al. says that the sea level will be lower due to the ice in the polar region, and refers to the IPCC (Inter-governmental Panel on Climate Change) assessment reports as if these reports would have supported the notion. The referred sections of IPCC reports, however, describe the effects of “polar ice sheets” of Antarctica and Greenland combined, and not “ice in the polar region” as Endo et al. says. The misinterpretations of these terms also lead to their unfounded and untenable criticism on the “White Paper on the Environment” published by the Ministry of the Environment, Japan.
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