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Semisolid casting with ultrasonically melt-treated billets of Al-7mass%Si alloys

China Foundry 2012年第1期9卷 78-83页

作者： Yoshiki Tsunekawa Masahiro Okumiya Takahiro Motomura toyota technological institute

Abstract： The demand for high performance cast aluminum alloy components is often disturbed by increasing impurity elements, such as iron accumulated from recycled scraps. It is strongly required that coarse plate-like iron compound of β-Al5FeSi turns into harmless form without the need for applying refining additives or expensive virgin ingots. The microstructural modification of Al-7mass%Si alloy billets with different iron contents was examined by applying ultrasonic vibration during the solidification. Ultrasonically melt-treated billets were thixocast right after induction heating up to the semisolid temperature of 583 ℃, the microstructure and tensile properties were evaluated in the thixocast components. Globular primary reAl is required to fill up a thin cavity in thixocasting, so that the microstructural modification by ultrasonic melt-treatment was firstly confirmed in the billets. With ultrasonic melt-treatment in the temperature range of 630 ℃ to 605 ℃, the primary α-AI transforms itself from dendrite into fine globular in morphology. The coarse plate-like β-AIsFeSi compound becomes markedly finer compared with those in non-treated billets. Semisolid soaking up to 583 ℃, does not appreciably affect the size of β-AIsFeSi compounds; however, it affects the solid primary reAl morphology to be more globular, which is convenient for thixocasting. After thixocasting with preheated billets, eutectic silicon plates are extremely refined due to the rapid solidification arising from low casting temperature. The tensile strength of thixocast samples with different iron contents does not change much even at 2mass% of iron, when thixocast with ultrasonically melt-treated billets. However, thixocast AI-7mass%Si-2mass%Fe alloy with non-treated billets exhibits an inferior strength of 80 MPa, compared with 180 MPa with ultrasonically melt-treated billets. The elongation is also improved by about a factor of two in thixocastings with ultrasonically melt-treated billets

关键词： cast Al-Si alloy ultrasonic radiation thixocasting α-Al iron compound

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Hot-Dip Coating of Lead-free Aluminum on Steel Substrates with Ultrasonic Vibration

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Journal of Materials Science & Technology 2008年第1期24卷 41-44页

作者： Y. Tsunekawa S. Tamura M. Okumiya N.Ishihara toyota technological institute Tempaku Nagoya 468-8511 Japan

Hot-dip coating has been practically employed in manufacturing zinc alloy coated steel ***,it is difficult to coat aluminum alloy on a bulky steel substrate without sufficient preheating,because a rapidly solidified layer containing gas babbles is formed on a substrate surface.A variety of iron-aluminides are also formed at the interface of a steel and aluminum hot-dip coating system,which is the main difficulty in joining of steel with *** vibration was applied to a steel substrate during hot-dip coating of aluminum alloy to control a rapidly solidified layer and a brittle reaction *** dipping of columnar steel substrates into molten aluminum alloy （Al-2.7 mass fraction Si-4.6 mass fraction Sn） was carried out through the use of a Langevin oscillator with resonant frequency of 19.5 *** application of ultrasonic vibration is quite effective to control a rapidly solidified layer and a surface oxide layer from a substrate surface by the sonocapillary effect based on a cavitation phenomenon,so that the intimate contact is achieved at the beginning of hot-dip *** application of ultrasonic vibration to hot-dipping is effective to control a reaction layer with less than 5 #m in *** impact test exhibits that the good adhesive strength is approved in hot-dipped aluminum coatings with a thin reaction layer of approximately 5μm.

关键词： Ultrasonic vibration Cavitation Sono-Capillary effect Hot-dip coating

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Improvement in mechanical properties of hypereutectic Al-Si-Cu alloys through sonosolidified slurry

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China Foundry 2014年第4期11卷 396-401页

作者： Yoshiki Tsunekawa Shinpei Suetsugu Masahiro Okumiya Naoki Nishikawa Yoshikazu Genma toyota technological institute TenpakuNagoya 468-8511Japan toyota Motor Corporation Toyota 471-8571Japan

For the wider applications,it is necessary to improve the ductility as well as the strength and wear-resistance of hypereutectic AlSi-Cu alloys,which are typical light-weight wear-resistant *** increase in the amounts of primary silicon particles causes the modified wear-resistance of hypereutectic Al-Si-Cu alloys,but leads to the poor strength and *** is known that dual phase steels composed of hetero-structure have succeeded in bringing contradictory mechanical properties of high strength and ductility *** order to apply the idea of hetero-structure to hypereutectic Al-Si-Cu alloys for the achievement of high strength and ductility along with wear resistance,ultrasonic irradiation of the molten metal during the solidification,which is called sono-solidification,was carried out from its molten state to just above the eutectic *** sono-solidified Al-17Si-4Cu alloy is composed of hetero-structure,which are,hard primary silicon particles,soft non-equilibrium a-Al phase and the eutectic ***-casting was performed at just above the eutectic temperature with sono-solidified slurry to shape a disk *** the rheo-casting with modified sonosolidified slurry held for 45 s at 570 oC,the quantitative optical microscope observation exhibits that the microstructure is composed of 18area%of hard primary silicon particles and 57area%of soft a-Al *** contrast,there exist only 5 area%of primary silicon particles and no a-Al phase in rheo-cast specimen with normally solidified *** the tensile tests of T6 treated rheo-cast specimens with modified sono-solidified slurry exhibit improved strength and 5%of elongation,regardless of having more than 3 times higher amounts of primary silicon particles compared to that of rheo-cast specimen with normally solidified slurry.

关键词： semisolid casting slurry ultrasonic vibration sonosolidification hetero-structure hypereutectic aluminum alloy primary silicon a-Al solid solution

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Magnetic properties of soft layer/FePt-MgO exchange coupled composite perpendicular recording media

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Chinese Physics B 2008年第10期17卷 3907-3909页

作者：阴津华 Takao Suzuki 潘礼庆 Department of Physics University of Science and Technology Beijing Information Storage Materials Laboratory Toyota Technological Institute

The magnetic properties of exchange coupled composite （ECC） media that are composed of perpendicular magnetic recording media FePt MgO and two kinds of soft layers have been studied by using an x-ray diffractometer, a polar Kerr magneto-optical system （PMOKE） and a vibrating sample magnetometer （VSM）. The results show that ECC media can reduce the coercivities of perpendicular magnetic recording media FePt-MgO. The ECC media with granular-type soft layers have weaker exchange couplings between magnetic grains and the magnetization process, for ECC media of this kind mainly follow the Stoner Wohlfarth model.

关键词： exchange coupled composite media perpendicular magnetic recording media magnetic properties

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Microwave Application Shape Anisotropy of Micro-sized Bamboo Blind Shape

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Journal of Iron and Steel Research International 2012年第S2期19卷 826-829页

作者： Keisuke Fujisaki toyota technological institute

Electromagnetic anisotropic characteristics in micro-sized water bamboo blind shape are observed by high frequency electromagnetic computation,which is applied to the material constants *** assuming that the micro-sized unit structure is repeated in 3-dimensional space and its size is much smaller than the electromagnetic wave length,the micro-sized electromagnetic field calculation is carried *** the micro-structure shapes of the material are different even if they are the same volume rate,different dielectric constant characteristics are *** reasons are considered to be a generation of de-electrification within the dielectric material.

关键词： micro-sized model shape anisotropy microwave bamboo blind shape

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STRUCTURAL PHASE TRANSITION OF ALIPHATIC NYLONS VIEWED FROM THE WAXD/SAXS AND VIBRATIONAL SPECTRAL MEASUREMENTS AND MOLECULAR DYNAMICS CALCULATION

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Chinese Journal of Polymer Science 2007年第1期25卷 73-82页

作者： Kohji Tashiro Department of Future Industry-Oriented Basic Science and Materials Toyota Technological InstituteTempakuNagoya 468-8511Japan

The crystalline phase transition of aliphatic nylon 10/10 has been investigated on the basis of the simultaneous measurement of wide-angle and small-angle X-ray scatterings, the infrared spectral measurement and the molecular dynamics calculation. An interpretation of infrared spectra taken for a series of nylon samples and the corresponding model compounds was successfully made, allowing us to assign the infrared bands of the planar-zigzag methylene segments reasonably. As a result the methylene segmental parts of molecular chains were found to experience an order-to-disorder transition in the Brill transition region, where the intermolecular hydrogen bonds are kept alive although the bond strength becomes weaker at higher temperature. The small-angle X-ray scattering data revealed a slight change in lamellar stacking mode in the transition region. The crystal structure has been found to change more remarkably in the temperature region immediately below the melting point, where the conformationally disordered chains experienced drastic rotational and translational motions without any constraints by hydrogen bonds, and the lamellar thickness increased largely along the chain axis. These experimental results were reasonably reproduced by the molecular dynamics calculation performed at the various temperatures.

关键词： Aliphatic nylon Phase transition Wide-angle X-ray diffraction Small-angle X-ray scattering Computer simulation.

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An Assessment of ICT-Based Education for Mechanical Engineering in technological Educational institute of Patras, Greece

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通讯和计算机（中英文版） 2010年第10期7卷 37-44页

作者： Georgios Kabouridis Mechanical Department of technological Educational institute Patras 26334 Greece

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Hierarchical hybrid testability modeling and evaluation method based on information fusion

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Journal of Systems Engineering and Electronics 2015年第3期26卷 523-532页

作者： Xishan Zhang Kaoli Huang Pengcheng Yan Guangyao Lian Ordnance Engineering College Ordnance technological Research institute

In order to meet the demand of testability analysis and evaluation for complex equipment under a small sample test in the equipment life cycle, the hierarchical hybrid testability model- ing and evaluation method （HHTME）, which combines the testabi- lity structure model （TSM） with the testability Bayesian networks model （TBNM）, is presented. Firstly, the testability network topo- logy of complex equipment is built by using the hierarchical hybrid testability modeling method. Secondly, the prior conditional prob- ability distribution between network nodes is determined through expert experience. Then the Bayesian method is used to update the conditional probability distribution, according to history test information, virtual simulation information and similar product in- formation. Finally, the learned hierarchical hybrid testability model （HHTM） is used to estimate the testability of equipment. Compared with the results of other modeling methods, the relative deviation of the HHTM is only 0.52%, and the evaluation result is the most accu rate.

关键词： small sample complex equipment hierarchical hybrid information fusion testability modeling and evaluation.

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Efects of amine, amine salt and amide on the behaviour of carbon dioxide absorption into calcium hydroxide suspension to precipitate calcium carbonate

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Journal of Environmental Sciences 2013年第12期25卷 2507-2515页

作者： Wittaya Chuajiw Mitsuru Nakano Kazumasa Takatori Toshiya Kojima Yoshiki Wakimoto Yoshiaki Fukushima toyota technological institute 2-12-1 HisakataTempaku-kuTenpaku Moon Chome toyota Central R&D Labs. Inc. Yokomichi Aisin Seiki Co. Ltd.2-1Asahi-machi

The amount of carbon dioxide （CO2） absorption and calcium ion （Ca^2＋） concentration besides the pH of aqueous solution were observed during the COz absorption to precipitate calcium carbonate （CaCO3） from calcium hydroxide （Ca（OH）2）. A reaction rate-limiting effect of an amount of CO2 absorption without any organic additives in the early stage of the precipitation was observed, which was attributed to an interruption effect of bicarbonate ion （HCO3） on the precipitation of CaCO3. The improvement for the reaction rate was achieved not only by amine additives but also by neutral additives such as ε-caprolactam or amine salt. When the hexamethylene diamine was dissolved in the solution, successive change of crystal forms of CaCO3 aragonite to calcite in aqueous suspensions, confirmed by Ca^2＋ concentration change and X-ray diffraction, was concluded that a local environment around the amine group in aqueous solution and an interaction of the diamine with precipitated CaCO3 particles were important factors for these reactions.

关键词： carbon dioxide absorption calcium carbonate precipitation local functional group interaction

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Combustion characteristic and aging behavior of bimetal thermite powders

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Defence Technology（防务技术） 2021年第3期17卷 755-762页

作者： Hong-qi Nie Hay Yee Chan Sreekumar Pisharath Huey Hoon Hng Energetics Research institute Nanyang Technological UniversitySingapore

Nanothermites have been employed as fuel additives in energetic formulations due to their higher energy density over CHNO energetics. Nevertheless, sintering and degradation of nanoparticles significantly limit the practical use of nanothermites. In this work, combustion characteristic and aging behavior of aluminum/iron oxide(Al/Fe2O3) nanothermite mixtures were investigated in the presence of micron-scale nickel aimed to produce bimetal thermite powders. The results showed that the alumina content in the combustion residue increased from 88.3% for Al/Fe2O3 nanothermite to 96.5% for the nanothermite mixture containing 20 wt% nickel. Finer particle sizes of combustion residue were obtained for the nanothermite mixtures containing nickel, indicative of the reduced agglomeration. Both results suggested a more complete combustion in the bimetal thermite powders. Aging behavior of the nanothermite mixture was also assessed by measuring the heat of combustion of the mixture before and after aging process. The reduction in heat of combustion of nanothermite mixtures containing nickel was less severe as compared to a significant decrease for the nanothermite mixture without nickel, indicating better aging resistance of the bimetal thermite powders.

关键词： Nanothermite Bimetal Combustion efficiency Aging Thermochemical calculations

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