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Mabuchi Y.,Nagoya Institute of Technology | Itoigawa F.,Nagoya Institute of Technology | Nakamura T.,Nagoya Institute of Technology | Kawata K.,Aichi Center for Industry and Science Technology | Suganuma T.,Takahiro Engineering Works Ltd.
Key Engineering Materials

Precision grinding is one of the important processes for finishing of hardened steel parts. However, the grinding process might be quite costly providing the parts with shape complexity should be finished because a number of production steps are needed. Also, this process has some environmental issues, such as disposal of a large amount of grinding sludge and grinding fluid. Precision cutting would become a better alternative process to reduce cost and environmental burden because process steps can be simplified by use of CNC machine tools with PcBN cutting insert if deterioration of cutting tool edge by wear and chipping can be suppressed for long duration. In this study, to improve performance of a PcBN cutting insert, such as wear resistance and defect resistance by the applying of pulse laser processing to sharpen cutting edge in order to realize substitution of cutting for grinding. Precision cutting experiments for hardened steel are conducted by use of the PcBN insert with sharp and tough edges processed by pulsed laser and, for comparison, by use of the PcBN insert ground with diamond wheel. From the results of cutting experiments, it was found that precision cutting with PcBN insert processed by pulsed laser can provide a steady cutting state for a long cutting duration, and a smooth finished surface comparable to precision grindings. © (2015) Trans Tech Publications, Switzerland. Source

Miki M.,Kyoto Institute of Technology | Suzuki T.,Aichi Center for Industry and Science Technology | Yamada Y.,Kanagawa University
Journal of Photopolymer Science and Technology

Physical and gas transport properties of amine-terminated hyperbranched polyimide-silica hybrid (AM-HBPI-silica hybrid) membranes prepared with a dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, and a triamine, 1,3,5-tris(4-amino-phenoxy)benzene, were investigated and compared with those of dianhydride-terminated hyperbranched polyimide-silica hybrid (DA-HBPI-silica hybrid) membranes. HBPI-silica hybrid membranes were prepared via sol-gel reaction using hyperbranched polyamic acid of which end groups were modified with silane coupling agents, water and tetramethoxysilane. Although the AM-HBPI membrane was colored to dark brown, optical transmittances of AM-HBPI-silica hybrid membranes increased with increasing silica content. Thermal and dimensional stability of AM-HBPI-silica hybrids are higher than those of DA-HBPI-silica hybrids because of the rigidity of AM-HBPI molecular chains which contain more branching units. Gas permeability and CO2/CH4 selectivity of DA-and AM-HBPI-silica hybrid membranes increased with increasing silica content. Especially, CO2/CH4 selectivity of AM-HBPI-silica hybrid membranes remarkably increased with increasing silica content. This behavior is probably due to the characteristic distribution and interconnectivity of free volume holes created by the incorporation of silica and the high affinity of hydroxyl groups remaining in the silica domain to CO2. © 2013SPST. Source

Yamamoto N.,Nagoya University | Yoshida T.,EcoTopia Science Institute | Yagi S.,EcoTopia Science Institute | Like Z.,Nagoya University | And 4 more authors.
e-Journal of Surface Science and Nanotechnology

We have prepared silver-loaded gallium oxide (Ag/Ga2O 3) photocatalysts by the solution plasma method (SPM) and impregnation method (imp), and investigate the effects of the chemical states and the size of the Ag nanoparticles on their photocatalytic activities. The photocatalytic reduction of CO2 with water proceeds over all the Ag/Ga2O3 photocatalysts to produce CO, however the CO production rates decrease during photocatalytic reaction. Measurements of UV-VIS diffuse reflectance spectra, XANES spectra and TEM images reveal the followings: the Ag oxide nanoparticles in the as-prepared Ag/Ga 2O3 (imp) samples exist and their size distribution is wide from 5 to 10 nm. They become a lot of metallic nanoparticles by UV light-irradiation, and become larger particles with the size of ca. 20 nm during the photocatalytic reaction. On the other hand, the Ag nanoparticles in the as-prepared Ag/Ga2O3 (SPM) samples are metallic with the size of less than 10 nm. The size does not change under UV light irradiation, while become larger particles during the photocatalytic reaction as similar to the case of the Ag/Ga2O3 (imp) samples. Such small metallic Ag nanoparticles with the size of 5-10 nm are suitable for CO production. However, they aggregate during the reaction for 5 h to degrade the photocatalytic activity. © 2014 The Surface Science Society of Japan. Source

Nishida M.,Nagoya Institute of Technology | Ichihara H.,Nagoya Institute of Technology | Watanabe H.,Nagoya Institute of Technology | Fukuda N.,Aichi Center for Industry and Science Technology | Ito H.,Industrial Research Center
Engineering Transactions

Poly(lactic acid) (PLA) and poly(butylene adipate/terephthalate) (PBAT) were used for polymer alloys, and the effects of the mixing ratio of PLA and PBAT and the addition of dialkyl peroxide (compatibilizing agent) were examined. The stress-strain curves of PLA/PBAT and PLA/PBAT/dialkyl peroxide specimens were measured using a tensile split Hopkinson bar (Kolsky Bar) method and a universal testing machine. The mixing ratio of PLA and PBAT and the dialkyl peroxide addition affected the shape of the stress-strain curve behavior. Regardless of the strain rate, the yield stress decreased and the elongation at break and strain energy increased with increasing PBAT content when the dialkyl peroxide was used. At high strain rate, the dialkyl peroxide addition increased the elongation at break and the strain energy, and changed the fracture surface to a whitened form that was markedly uneven. This result could explain the improvement in the Izod impact strength. Source

Suzuki D.,Nagoya Institute of Technology | Itoigawa F.,Nagoya Institute of Technology | Kawata K.,Aichi Center for Industry and Science Technology | Nakamura T.,Nagoya Institute of Technology
International Journal of Automation Technology

Polycrystalline Cubic Boron Nitride (PcBN) cutting tools have excellent characteristics, such as a high degree of hardness and low chemical reactivity, so they have the potential to replace the high precision grinding of hardened steel with high precision cutting. However, there are some problems inherent in so-called sintered materials, including low formability and unsteady wear. In order to solve these problems, pulsed laser processing is applied to shape a cutting edge. In this study, first PcBN cutting tools processed by lasers are adopted to the high-precision turning of hardened steel with 58HRC. As the result, these PcBN cutting tools provide a steady cutting state and a smoother finished surface. Second, in order to investigate these advantages of PcBN cutting tools processed by laser, individual requirements of the cutting tool are investigated: edge sharpness, surface quality including micro-defects, surface hardness, and friction coefficient. The results indicate that tools processed by laser have sharper edges and smoother, harder, and lowerfiction surfaces, compared to ground tools. Above all, the increase in surface hardness improves cutting performance because of it provides higher wear resistance. Source

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