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Aogaki R.,Kanagawa University | Morimoto R.,Saitama Industrial Technology Center | Asanuma M.,Yokohama Polytechnic College
Journal of Magnetism and Magnetic Materials | Year: 2010

In copper electrodeposition under a magnetic field parallel to electrode surface, different roles of two kinds of nonequilibrium fluctuations for micro-magnetohydrodynamic (MHD) effects are discussed; symmetrical fluctuations are accompanied by the suppression of three dimensional (3D) nucleation by micro-MHD flows (the 1st micro-MHD effect), whereas asymmetrical fluctuations controlling 2D nucleation yield secondary nodules by larger micro-MHD flows (the 2nd micro-MHD effect). Though the 3D nucleation with symmetrical fluctuations is always suppressed by the micro-MHD flows, due to the change in the rate-determining step from electron transfer to mass transfer, the 2D nucleation with asymmetrical fluctuations newly turns unstable, generating larger micro-MHD flows. As a result, round semi-spherical deposits, i.e., secondary nodules are yielded. Using computer simulation, the mechanism of the 2nd micro-MHD effect is validated. © 2009 Elsevier B.V. All rights reserved.

« China researchers devise process to convert biomass to gasoline via one-step DME synthesis: DTG | Main | Schaeffler presents high-performance 48V concept mild hybrid vehicle at Aachen » The Nikkei, citing unnamed sources, reports that R&D organization Saitec (Saitama Industrial Technology Center) and Honda Motor have developed a practical magnesium-ion rechargeable battery and hope to commercialize it. Saitec reportedly led the development; Honda R&D assessed the technology’s viability. The two are slated to announce the battery next month. Because magnesium is divalent, it can displace double the charge per ion (i.e., Mg2+ rather than Li+). As an element, magnesium is much more abundant than lithium, and more stable. Magnesium-ion batteries theoretically could offer good electrochemical performance, while being safer and less expensive than Li-ion batteries. Toyota has been looking into Mg-ion systems for a number of years (earlier post). However, Mg-ion batteries have suffered from a number of limitations, resulting in rapid degradation of performance. According to the report, the developers use vanadium oxide in the cathode, making it easier for ions to move between it and the magnesium-based anode. The vanadium oxide allows for more charges without deterioration, the sources said. For safety, the team added an organic substance that lowers the risk of magnesium catching fire. In a 2014 paper (Inamoto et al.), Saitec researchers had reported using a vanadium pentoxide xerogel containing sulfur (S-V O gel) as a cathode for Mg-ion batteries. Charge-discharge tests of that system revealed a specific capacity of 450 mAh g-1, and cyclic voltammetry was almost perfectly stabilized after the second cycle. According to the Nikkei’s source, the prototype magnesium-ion battery performs as well as a Li-ion counterpart in terms of life and safety. The developers are now working with a number of battery makers to come up with a way to mass produce the battery. According to the Nikkei, the developers expect to first commercialize the technology in smartphones and other portable devices.

Inamoto M.,Saitama Institute of Technology | Inamoto M.,Saitama Industrial Technology Center | Kurihara H.,Saitama Industrial Technology Center | Yajima T.,Saitama Institute of Technology
Materials | Year: 2013

Multivalent cation rechargeable batteries are expected to perform well as high-capacity storage devices. Rechargeable magnesium batteries have an advantage in terms of resource utilization and safety. Here, we report on sulfur-doped vanadium pentoxide (S-V2O5) as a potential material for the cathodes of such a battery; S-V2O5 showed a specific capacity of 300 mAh·g-1. S-V2O5 was prepared by a method using a low-temperature plasma generated by carbon felt and a 2.45 GHz microwave generator. This study investigates the ability of S-V2O5 to achieve high capacity when added to metal oxide. The highest recorded capacity (420 mAh·g-1) was reached with MnO2 added to composite SMn-V2O5, which has a higher proportion of included sulfur than found in S-V2O5. Results from transmission electron microscopy, energy-dispersive X-ray spectroscopy, Micro-Raman spectroscopy, and X-ray photoelectron spectroscopy show that the bulk of the SMn-V2O5 was the orthorhombic V2O5 structure; the surface was a xerogel-like V2O5 and a solid solution of MnO2 and sulfur. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

Inamoto M.,Saitama Industrial Technology Center | Inamoto M.,Saitama Institute of Technology | Kurihara H.,Saitama Industrial Technology Center | Kurihara H.,Saitama Institute of Technology | And 2 more authors.
Electrochemistry | Year: 2012

Vanadium pentoxide xerogel was prepared by irradiation with microwaves and successfully applied as the active cathode material of a magnesium rechargeable battery. The structure and electrochemical properties of the V 2O 5 xerogel were investigated and compared with V 2O 5 prepared by conventional heat-treatment. X-ray diffraction revealed that the V 2O 5 xerogel prepared by MW irradiation has low crystalline structure. Charge-discharge tests revealed a specific capacity of 463mAhg -1, which was much larger than OfV 2O 5 prepared by conventional heattreatment (190mAhg -1). © The Electrochemical Society of Japan All rights reserved.

Sano M.,Saitama Industrial Technology Center | Sano M.,Tokyo Institute of Technology | Oguma H.,Saitama Industrial Technology Center | Sekine M.,Saitama Industrial Technology Center | And 2 more authors.
International Journal of Adhesion and Adhesives | Year: 2014

In this study, high-frequency (HF) welding of glass-fiber-reinforced polypropylene (GF/PP) was investigated with thermoplastic adhesive layers including SiC, which is able to heat by HF irradiation. The influences of SiC particle size and content on the dielectric properties of an adhesive layer were investigated experimentally. The influence of temperature on the tan δ/ε′ value was also investigated. In the HF welding process of GF/PP bonded with the thermoplastic adhesive layer, the effects of SiC content and particle size on the welding properties were examined. The GF/PP was completely welded in a short time when SiC with small particle size and high content was included in the adhesive and a good bond strength was also achieved. Thus, short time and high bond strength for the welding were achieved with the method using a thermoplastic adhesive layer with high tan δ/ε′ value. © 2014 Elsevier Ltd.

Iizuka S.,Saitama Industrial Technology Center | Murata K.,Saitama Industrial Technology Center | Sekine M.,Saitama Industrial Technology Center | Sekine M.,Waseda University | Sato C.,Tokyo Institute of Technology
Polymer Testing | Year: 2016

Water vapor transmission rate (WVTR) measurements with the conventional cup method do not yield accurate values at high temperatures because the film specimens deform and are damaged owing to air expansion in the cup. A new cup with a pressure-adjusting mechanism allows measurements at 85°C and prevents specimen deformation and damage. WVTRs of polypropylene (PP) and polyethylene terephthalate (PET) measured with the new cup method are the same as those measured with the conventional cup method at 40°C, and gas chromatographic detection method at 60°C and 85°C. Arrhenius plots of the water vapor permeability coefficient of PP, polyethylene naphthalate (PEN) and polyimide (PI) with the new cup method show a linear relationship in the range 25-85°C. In the same range, Arrhenius plots of PET, polybutylene terephthalate (PBT) and polylactic acid (PLA) have bending points corresponding to the glass transition temperatures of the materials. © 2015 Elsevier Ltd. All rights reserved.

Ohta N.,Saitama University | Ohba D.,Saitama University | Sato S.,Saitama University | Tang Z.,Saitama University | And 3 more authors.
Thin Solid Films | Year: 2011

Rapid thermal annealing of sputter-deposited ZnO and Al-doped ZnO (AZO) films with and without an amorphous silicon (a-Si) capping layer was investigated using a radio-frequency (rf) argon thermal plasma jet at atmospheric pressure. The resistivity of bare ZnO films on glass decreased drastically from 106 to 103 Ω•cm at maximum surface temperatures Tmax above 650 °C, whereas the resistivity increased from 10- 4 to 10- 3-10- 2 Ω•cm for bare AZO films. On the other hand, the resistivity of AZO films with a 30-nm-thick a-Si capping layer remained below 10- 4 Ω•cm, even after TPJ annealing at a Tmax of 825 °C. X-ray diffraction and X-ray photoemission electron studies revealed that the film crystallization of both AZO and a-Si layers was promoted without the formation of an intermixing layer. Additionally, the crystallization of phosphorous- and boron-doped a-Si layers at the sample surface was promoted, compared to that of intrinsic a-Si under identical plasma annealing conditions. The role of the a-Si capping layer on sputter-deposited AZO and ZnO films during TPJ annealing is demonstrated. The effects of the mixing of phosphorous and boron impurities in a-Si:H during TPJ annealing of flat and textured AZOs are also discussed. © 2011 Elsevier B.V.

Yamada T.,Saitama Industrial Technology Center | Murata Y.,Nippon Institute of Technology | Yokoi H.,University of Tokyo
International Polymer Processing | Year: 2012

In this study, cross-sectional analyses were performed on microcellular injection-molded high-impact polystyrene products. The results confirm that the following five types of layers were formed: Skin layers I (the silver streak layer) and II (a nonfoamed layer), Core layers I (cell diameter, d > 150 lm), II (d < 50 lm), and III (d > 100 lm). As the maximum in-mold pressure (Pmax) was increased from 5 to 30 MPa, the thickness of Skin layer II remained nearly constant. However, the foam types in the core layers changed from I and II to II and III or III only, resulting in an increase in cell diameter and a decrease in cell density. The process of cellular structure formation was observed using a glass-inserted mold, which revealed that this process consists of a flow (with a burst of cells at the melt front and the subsequent flow of the melt containing the cells), an end of the filling (involving elastic compression or the dissolution and disappearance of cells formed in the flow stage), and a cooling (new cell generation and growth and cooling solidification). Based on these cross-sectional observations, in concert with meltpressure measurements and visualizations, we developed a model describing the formation process of Skin layer II and the core layers including a new concept that considers the melt pressure inside the cavity. The following layers are incorporated into the model: Skin layer II: A nonfoamed layer is formed in the area of the melt front where gases diffuse out from within the melt during the filling stage, and this nonfoamed layer moves to from melt front to the surface of the product due to fountain flow. Core layers I and II: A multilayer is formed containing a distribution of cells preserved from the flow stage due to the low compression forces, Core layer III: cells are dissolved in the melt due to strong compression forces at the end of the filling stage and then reform and grow in the cooling stage. © Carl Hanser Verlag, Munich Intern.

Isobe N.,University of Tokyo | Sekine M.,Saitama Industrial Technology Center | Kimura S.,University of Tokyo | Wada M.,University of Tokyo | And 2 more authors.
Cellulose | Year: 2011

Cellulose-synthetic polymer nanocomposite films were prepared by immersion of cellulose gel in polymer solutions followed by dry casting. The cellulose hydrogel was prepared from aqueous alkali-urea solution. As the synthetic polymer, polystyrene (PS) and poly(methyl methacrylate) (PMMA) were used. The polymer content could be changed between 10 and 80% by changing polymer concentration of immersing solution. While the mechanical properties of the cellulose-PMMA composite films showed a nearly linear dependence on PMMA content, those of cellulose-PS composites showed an anomalous behavior; both tensile strength and Young's modulus showed prominent maxima at 15-30 wt% PS contents. This anomaly may have resulted from the specific interaction between the aromatic ring of PS and the hydrophobic plane of the glucopyranoside. Both PMMA and PS composite films showed significant improvements in dimensional thermal stability; up to 25 wt% synthetic polymer content, the coefficient of thermal expansion (CTE) was as low as ca. 30 ppm/K, about 1/3 of the pure polymers. This indicates that the regenerated cellulose network is effective in suppressing thermal expansion of the synthetic polymers. © 2011 Springer Science+Business Media B.V.

Sano M.,Saitama Industrial Technology Center | Oguma H.,Saitama Industrial Technology Center | Sekine M.,Saitama Industrial Technology Center | Sato C.,Tokyo Institute of Technology
International Journal of Adhesion and Adhesives | Year: 2013

In this study, high-frequency welding of polypropylene by melting composite adhesive layers containing dielectric ceramics was investigated. Various dielectric ceramics were mixed in a fixed ratio with polypropylene to make the composite adhesive layers, and the resulting dielectric properties were measured using an impedance analyser. The highest loss factor in the composite adhesive layer was found when 40 vol% silicon carbide (SiC) was used in the mixture. Dynamic viscoelasticity measurements showed that all composite adhesive layers softened at approximately 170 C and melted (fluidised) at approximately 190 C. Each composite adhesive layer was inserted between two polypropylene plates, and irradiated at a frequency of 40 MHz. The composite adhesive layers that included 20 vol% anatase-titanium oxide, 20 vol% or 40 vol% zinc oxide and 20 vol% or 40 vol% SiC melted in 40-70 s. The bond strength of the welded material obtained was high, and the adherend failure occurred by a tensile lap shear test. The heating efficiencies of the composite adhesive layers by high-frequency radiation were related to the tanδ/ε′ value of the composites. © 2013 Elsevier Ltd.

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