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Tamura T.,Japan National Institute of Advanced Industrial Science and Technology | Matsuki T.,Yamagata Research Institute of Technology | Miwa K.,Japan National Institute of Advanced Industrial Science and Technology
Materials Transactions | Year: 2011

It is known that mechanical vibrations which applied during solidification affect microstructure refinement. However, it is not completely understood which factor of vibrations is important for microstructure refinement. Factors of vibrations are frequency, acceleration, velocity and amplitude. In this study, the effect of mechanical vibrations on microstructure refinement of Al-7 mass % Si alloys was investigated systematically. The mechanical vibrations were applied to the melt in an alumina crucible from about 923 K to 863 K, and the crucible was quenched in water at 863 K. As a result, it was found that the velocity of mechanical vibrations corresponding to the vibration energy is important factor for primary crystals refinement. The mechanical vibrations with high velocity regardless of frequency can refine the primary crystals. It is considered that the mechanical vibrations promote heterogeneous nucleation just below the liquidus temperature. © 2011 The Japan Institute of Light Metals. Source


Tobitsuka K.,Yamagata Research Institute of Technology
Nippon Shokuhin Kagaku Kogaku Kaishi | Year: 2013

La France pear is one of the most popular European pears in Japan. Its typical charms include the fine aroma and the smooth texture. In Japan, Yamagata prefecture is one of the major La France pear-producing areas. To promote new local specialty processed foods and drinks in the Yamagata district, we developed two new food materials made from La France pear. One is a powdered material, "La France powder", and the other is a liquid material, "La France essence". Their beneficial characteristics include their natural and fine aroma. They are currently being utilized in the development of many new processed foods, drinks, etc. In this context, an overview of their development and examples of their applications are presented. Source


Saito H.,Yamagata Research Institute of Technology | Jung H.,Nagoya University | Shamoto E.,Nagoya University
Precision Engineering | Year: 2016

Elliptical vibration cutting of hardened die steel with coated carbide tools is examined in this research in order to achieve low-cost high-precision machining. Diamond coated tools are applied because of superior hardness of their polycrystalline diamond coating and its low manufacturing cost. TiN coated tools are also tested, since they are widely used for conventional machining of steels. Machinability of hardened die steel by the elliptical vibration cutting with coated carbide tools is discussed in three aspects in this study, i.e. transferability of cutting edge profile to cut surface, cutting force, and tool life. The transferability is evaluated quantitatively by calculating correlation coefficients of measured roughness profiles. It is clarified that the diamond coated tools have high transferability which leads to diffraction of light on the surface machined at micro-scale pick feed. Total cutting forces including ploughing components are measured at various feed rates, and then shearing components and ploughing components are separated utilizing linear regression. The measured results indicate, for example, that the all forces become considerably smaller only when elliptical vibration is applied to the TiN coated tool without cutting fluid. It is also found that this considerable reduction of forces interestingly corresponds to higher friction coefficient, which is identified from the ploughing components. Tool life tests are carried out by various machining methods, i.e. elliptical vibration/ordinary wet/dry cutting with diamond/TiN coated tools. The result shows, for example, that the flank wear is smallest in the wet elliptical vibration cutting with the diamond coated tool. © 2016 Elsevier Inc. Source


Hirata M.,Yamagata Research Institute of Technology | Hirata M.,Yamagata University | Ochiai B.,Yamagata University | Endo T.,Kinki University
Journal of Polymer Science, Part A: Polymer Chemistry | Year: 2010

Star-shaped poly(phenoxy propylene sulfide) [poly (PPS)] were synthesized by anionic polymerization using a trifunctional initiator (I1) derived from a trifunctional five-membered cyclic dithiocarbonate and benzyl amine. Conditions for the anionic polymerization of PPS were optimized to obtain polymers with desired Mns and narrow MW/Mns. The best catalyst and solvent were DBU and DMF, respectively. The star-shaped structure of the resulting star poly(PPS) was supported by SEC analysis. The refractive indexes (nD) of the star poly (PPS) were relatively high (>1.64). © 2009 Wiley Periodicals, Inc. Source


Suzuki T.,Yamagata Research Institute of Technology | Konno T.,JUST Corporation
Precision Engineering | Year: 2014

Ni-based CNT composite (Ni-CNT) coatings were applied for improving the grain bonding strength of electroplated diamond tools. Further, since it is extremely important for the coatings to have good surface roughness for applications to micro-electroplated diamond tools, ultrasonic-vibration stirring was employed for improving the surface roughness of the coatings. The effects of the amount of CNTs in the plating bath on the hardness and grain bonding strength of Ni-CNT coatings were evaluated. Finally, we evaluated the tool life of microelectroplated diamond tools comprising Ni-CNT coatings as the topcoat layers by conducting experiments involving side machining and hole-drilling. The Vickers hardness of Ni-CNT coatings electroplated in a bath that contained more than 1-g/l CNTs exceeded 500 HV. The grain bonding strength can be improved by codepositing CNTs in Ni coatings and was almost 1.3 times in our estimations. In the case of the side machining of glass plates, electroplated diamond tools composed of the Ni-CNT coatings had a tool life approximately eight times longer than that of normal tools. Moreover, micro electroplated diamond tools also had a longer tool life for drilling holes in fused quartz glass. This represents the first experimental verification of the efficacy of Ni-CNT coatings in improving the grain bonding strength. In this manner, we have demonstrated that Ni-CNT coatings are extremely effective for improving the grain bonding strength of electroplated diamond tools. © 2014 Elsevier Inc. Source

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