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72 巻, 2 号
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門井 浩太, Norbert Babcsan, 中江 秀雄2008 年 72 巻 2 号 p. 73-79
発行日: 2008年
公開日: 2008/02/01
ジャーナル フリーAluminum foams are manufactured using various viscosity increasing methods at present. Although it is well known that calcium addition is one of the most successful thickening processes for fabricating fine foams, the intimate mechanism is still lacking. The aim of this paper is the investigation of the detailed thickening mechanism and the influence of increase viscosity conditions on fabricating aluminum foams. Thickened samples were prepared using pure aluminum admixed various contents of calcium or aluminum powder as viscosity increasing agents. Microstructure analysis of thickened samples was carried out. As quantitative evaluations, the measurements of stirring torques and oxygen contents were also performed. The effect of aluminum powder addition on the melt viscosity and microstructure of thickened sample cannot be confirmed. In the case of calcium addition, the stirring torques increase with the calcium content and the agitating time till the values achieve the stationary stage. More the oxide grains formed by folded oxide film are observed in the thickened sample which contains more the calcium amount. In addition, the oxygen content increases with the stirring time and the quantity of calcium addition. Thus, it is found that the oxide grain causes to increase the melt viscosity. Further, those content can be controlled by adjusting the calcium addition and the stirring time.
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米村 寛, 東雲 秀司, 永山 勝久2008 年 72 巻 2 号 p. 80-84
発行日: 2008年
公開日: 2008/02/01
ジャーナル フリーIn the last decades, Nd-Fe amorphous alloys have been studied by many methods because of high coercivity at room temperature and relation to Nd-Fe-B permanent magnets. In this study, we examined the effect of the containerless process for high undercooling and the metastable phase formation in detail.
In the gas levitating process, undercooling of Nd90Fe10 samples increased with cooling rate. Undercooling of Nd90Fe10 sample solidified at 268 K/s is ΔT=35 K. The primary α-Nd phases were surrounded by fine metastable phases. And the intergranular eutectic-like areas were comprised of α-Nd phase and metastable phase. In contrast, the sample with low undercooling was comprised of α-Nd phases and rod-like Nd2Fe17 phases among primary α-Nd phases. In Nd90Fe10 samples with undercooling of ΔT=35 K, coercivity of Nd90Fe10 samples is about 4.5 kOe at room temperature. This high coercivity is caused by fine crystallization of matastable phases.
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李 志旭, 中野 貴由, 豊澤 悟, 田畑 泰彦, 馬越 佑吉2008 年 72 巻 2 号 p. 85-90
発行日: 2008年
公開日: 2008/02/01
ジャーナル フリーOsteoclasts are nearly non-existent in mutant osteopetrotic (op/op) mice due to defects in the expression of the macrophage colony-stimulating factor (M-CSF). Thus, areal distribution of the biological apatite (BAp) c-axis in a femoral cross-section of the op/op mouse was investigated using a microbeam X-ray diffraction system in order to understand the role of osteoclasts on formation of BAp preferential alignment.
The incident X-ray beam was focused to 20 μm in diameter. The diffraction analysis was performed at 20 μm displacement intervals from the periosteal surface along the radial axis of the anterior portion at a cross-section of the center of the femoral diaphysis. The op/op mouse and its normal littermate used as a control were 12 weeks old.
The lack of osteoclasts induces both abnormality of the skeletal system and calcification of the medullary cavity, which are typical features of osteopetrosis. Preferential alignment of the BAp c-axis in the op/op mouse always shows a lower degree than that in the control mouse, regardless of the distance from the periosteum. Moreover, areal distributions of preferential alignment of the BAp c-axis on the femoral cross-section show quite different tendencies between the op/op and control mice. The preferential alignment of BAp gradually increases towards the periosteal surface in the op/op mouse due to the intramembranous ossification, while that in the control mouse is the lowest near the cortical envelope on the cross-section. This is because the decrease in the number of osteoclasts suppresses the normal modeling, resulting in degradation of preferential alignment of the BAp c-axis as a bone quality parameter in the op/op mouse.
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恒見 清孝, 和田 英樹2008 年 72 巻 2 号 p. 91-98
発行日: 2008年
公開日: 2008/02/01
ジャーナル フリーAntimony trioxide is a possible carcinogenic compound that affects humans through inhalation exposure. Therefore, antimony and antimony compounds were included in Class I of the Pollutant Release and Transfer Register (PRTR) list in Japan. In this study, the substance flow analysis of antimony, from its production to final disposal, was performed. The amounts of domestically supplied antimony, stocked antimony, and generated waste containing antimony were estimated for the period from 1970 to 2015 in order to conduct risk assessment of antimony and antimony compounds. Sensitivity analysis was also conducted in order to identify how the uncertain parameters affect the target values for sensitivity analysis in the substance flow of antimony. The amount of domestic waste generated was estimated to be ten thousand tons per year in 2015, which was nearly equal to the amount of domestic supply for the same year. The amount of recovered antimony was estimated to be over three times the amount in 2001, and it was strongly affected by policies relating to the sound material cycle society, particularly the Electric Appliance Recycling Law enacted in 2001. On the basis of this study, it was also concluded that the main source of emission into the air was automotive brake abrasion dust and the amount of emission was estimated to be around 100 t/year in 2001. Furthermore, the amount of emission into the air was largely controlled by two factors, the expected lifetime and future trend of the domestic supply of brake pads.
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中島 謙一, 横山 一代, 中野 加都子, 長坂 徹也2008 年 72 巻 2 号 p. 99-104
発行日: 2008年
公開日: 2008/02/01
ジャーナル フリーSubstance flow analysis (SFA) of indium has been conducted in this study. The purpose of this study is to identify the relevant issues for the development of an efficient indium recycling system by performing SFA of indium supplied for ITO processing as transparent electrodes, which accounts for 86.9% of the total indium demand. In this study, as part of the development of substance and material flow data, (1) data on the flow of indium was collected and reviewed, (2) the amount of dissipated indium associated with the production of flat-panel displays (FPDs) were estimated and (3) its environmental impact was also assessed.
The major conclusions are (a) 470 t-In is used in ITO for transparent electrodes, out of which 220 t-In is dissipated or potentially dissipated in Japan, and (b) 220 t-In of dissipated indium is equivalent to 11.4 TJ of energy consumption, 0.5×103 t of CO2 emissions, and 1.0×106 t of Total Materials Requirement (TMR).
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三谷 状士, 沙魚川 智之, 渡邊 千尋, 門前 亮一2008 年 72 巻 2 号 p. 105-110
発行日: 2008年
公開日: 2008/02/01
ジャーナル フリーUltra-sonic fatigue tests were carried out for W-Mo type high-speed steel specimens containing 40 ppm N (low N), 160 ppm N (middle N) and 400 ppm N (high N). The fatigue strength of the high-N specimen was lower than those of the low-N and middle-N specimens, which were nearly identical. The increase in N content caused no changes in average sizes of MC carbides, M6C carbides and carbides consisting of M6C and MC (M6C•MC), but increased the size of large MC carbides, such as the maximum size from about 6.5 μm to 13 μm. The fracture origin of the high-N specimen was coarse MC carbides of about 13 μm, and those of the low-N and middle-N specimens were large aggregates of about 12 μm, consisting of two or three M6C•MC carbides. Voids formed by decohesion of the M6C/MC interfaces in M6C•MC carbides larger than about 5 μm in the low-N, middle-N and high-N specimens, and those formed by destruction of MC carbides larger than about 8 μm in the high-N specimen were observed after fatigue fracture under a stress amplitude of 1100 MPa. This result arises because of greater stress concentration due to more inhomogeneous deformation around the MC and M6C•MC carbides develops as the sizes of both the carbides increase. In the high-N specimen, cracking was initiated from the voids in coarse MC carbides, while in the low-N and middle-N specimens, a crack propagated between two voids in adjacent large M6C•MC carbides which constitute a carbide aggregate. The fatigue strength of the high-N specimen is lower because the nucleation of the cracks from coarse MC carbides occurs more rapidly than that of the cracks in large M6C•MC carbide aggregates of the same size as the coarse MC carbides.
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横田 勝, 栃原 美佐子, 田中 正男, 長柄 毅一, 三船 温尚, 菅谷 文則, 宮原 晋一, 清水 康二2008 年 72 巻 2 号 p. 111-116
発行日: 2008年
公開日: 2008/02/01
ジャーナル フリーOn an ancient bronze mirror, we carried out a scanning electron microscopic (SEM) examination of fractured corrosion layers, a biological microscopic observation of a gram-stained sample and DNA analyses of the samples removed from corroded sites.
From these scientific and technical researches, we obtained the following results.
Fine particles about 2 μm in length were confirmed in the corrosion layer by the SEM observation. Microorganisms of the same size were observed in the gram-stained sample removed from the corrosion layer through a biological microscope. From these results, fine particles observed under the SEM should be considered as microorganisms. A lot of fine particles were confirmed especially in the corroded sites by the SEM observation. So (certain kinds of) microorganisms may have played a role in the corrosion (deterioration) of the ancient bronze mirrors while the mirrors were buried in soil.
From the base sequences obtained by DGGE analysis, two kinds of microorganisms were confirmed to exist in the corrosion layer of the ancient bronze mirror. One is 97.4% homologous to the 16S rDNA of the uncultured bacterium (Accession number: AY 053488). It was also highly homologous to the sequence derived from the 16S rDNA of the Xanthomonadaceae family such as Stenotrophomonas and Xanthomona. That is, the sequence is derived from a strain belonging to the Xanthomonadaceae family. The other base sequence is 97.4% homologous to the 16S rDNA of the Bacteroidales order such as uncultured Bacteroidales bacterium (Accession number: AY 859647). That is, the sequence is derived from a strain belonging to the Bacteroidales order.
Genes of microorganisms, presumed to belong to the Acetobacter, Gluconacetobacter genuses and Fe(III)-reducing bacterium, Shewanella algae were detected from the base sequence analysis by cloning.
From the results above, microbial activity is assumed to be high around the ancient bronze mirrors. The corrosion mechanism of bronze mirrors seems complicated, but a several types of microbes which possibly corrode bronze mirrors were verified.
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王 栄光, 中佐 啓治郎, 顔 旭2008 年 72 巻 2 号 p. 117-124
発行日: 2008年
公開日: 2008/02/01
ジャーナル フリーThe sputter etching of SUS304 stainless steel specimens was carried out, and the formation and growth processes of conical protrusions was investigated. In addition, the polarization behavior of the specimens in 3.5%NaCl aqueous solution and the surface morphology after the polarization test were examined. At an early stage of the sputter etching, the conical protrusions form mainly along grain boundaries. However, with increase in the sputter etching time the protrusions form also within the grains. With further increase in the sputter etching time, some protrusions grow largely and the entire surface is covered by the huge conical protrusions and the irregular small ones around them. The outer layer of the huge protrusion contains larger chromium but smaller nickel amount than matrix, and the interior has almost the same composition as the matrix. This means that the protrusion has a shell structure. For the specimen with short time sputter etching, the corrosion potential becomes nobler and the pitting corrosion potential becomes smaller, while the passive current density is smaller than those of non-sputter-etched specimen. In these specimens, the corrosion occurs preferentially along grain boundaries and around protrusions in grains. For the specimen with long time sputter etching, where the entire surface is covered by protrusions, the pitting corrosion potential increases and the corrosion progresses mainly from the interior of the specimen leaving the surface layer with many protrusions. In some cases, only the outer layer of the shell remains separately as a result of the corrosion of the interior and root of the huge protrusion.
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緒形 俊夫2008 年 72 巻 2 号 p. 125-131
発行日: 2008年
公開日: 2008/02/01
ジャーナル フリーA simple testing method for mechanical properties of materials in high-pressure hydrogen environments has been developed. This method does not require any high-pressure vessel but the high-pressure hydrogen environment is produced inside the hole in the specimen. The specimen temperature is easily controlled by outside environment. The effects of hydrogen environment embrittlement (HEE) for SUS304 and 304L at 298, 190, and 77 K were evaluated by the ratio of reduction of area obtained in tensile tests in hydrogen to that obtained in helium. The results of the evaluation by this testing method agreed fairly well with the results by the usual method using a high pressure vessel. The hole in the specimen was machined by electric discharge, wire-cut, and honing. The influence of surface roughness on HEE was compared among these processes and the wire-cut machining was found to be enough for this new method. Changes of HEE with temperature and fracture surface by hydrogen proved the usefulness of this new simple method.
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齋藤 繁, 黒川 一哉, 林 重成, 高島 敏行, 成田 敏夫2008 年 72 巻 2 号 p. 132-137
発行日: 2008年
公開日: 2008/02/01
ジャーナル フリーCompositions with tie-lines between the γ, α, σ, and δ phases in a ternary Re-Cr-Ni system were investigated by heat-treating various ternary Re-Cr-Ni alloys in vacuum at 1423 K for a variety of heating times up to 2500 h. The microstructures of the Re-Cr-Ni alloys that had been water-quenched after heating were observed and their Re, Cr and Ni concentration profiles were measured using an electron probe micro-analyzer (EPMA). It was found that a very long heat treatment was required to obtain equilibrium compositions of Ar-arc-melted Re-Cr-Ni alloys.
The tie-line compositions (at%) of each phase at 1423 K were experimentally determined, and an isothermal phase diagram was constructed. From these results, the γ, α, and σ phases of the three-phase coexistence state were found to have the following compositions: γ phase (3.0 at%Re, 45.6 at%Cr, and 51.4 at%Ni), α phase (16.1 at%Re, 75.2 at%Cr, and 8.7 at%Ni), and σ phase (16.3 at%Re, 60.3 at%Cr, and 23.4 at%Ni). In addition, the γ, σ, and δ phases have the following compositions: γ phase (13.3 at%Re, 18.1 at%Cr, and 68.6 at%Ni), σ phase (54.6 at%Re, 24.2 at%Cr, and 21.2 at%Ni), and δ phase (70.2 at%Re, 6.0 at%Cr, and 23.8 at%Ni).
The solubility limits of Ni in the σ phase increased from 19 at%Ni to 24 at%Ni, as the Cr content in the σ phase with a tie-line with the γ phase increased from 23 at%Cr to 61 at%Cr.
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