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Volume 49, Issue 3
Special Issue of 47th Summer Symposium
Displaying 1-11 of 11 articles from this issue
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Yasushi Hirabayashi, Sho Nakahira, Shinya Yamanaka, Toshiyuki Fujimoto ...2011 Volume 49 Issue 3 Pages 164-170
Published: March 10, 2012
Released on J-STAGE: March 22, 2012
JOURNAL FREE ACCESSFunctional plywood can produce constant heat by applying a voltage to the conductive bonding layer between wood sheets. Herein functional plywood was prepared by filling various microsized graphite particles (3.3-52.5μm in diameter) and nanosized carbon black (CB ; 29 nm) into a phenolic resin. To investigate the electrical conductivity, the resulting composite resin was coated onto a commercial glass slide. The effects of particle size, mass fraction of the conductive fillers (graphite and CB), and the weight ratio of graphite to the fillers (φ = graphite / (graphite + CB)) on the conductive properties of the composite resin, particularly the specific resistance and its variation coefficient, were estimated. A composite resin, which included at least 30 mass% of filler, yielded a relatively low variation coefficient for the specific resistance. Additionally, the composition of the resin had superior conductivity when the weight ratio was 55-66 mass% and the graphite particles were 22.9μm or less in diameter.
The above experiment indicated heating plywood was produced. Consequently, its surface temperature was measured. With respect to particle size, the standard deviation in the surface temperature of the plywood corresponded to that of the conductive properties on the glass slide. Hence, the method proposed herein using a glass slide is suitable for conductive characterization to determine the appropriate conditions to prepare heating plywood.View full abstractDownload PDF (919K) -
Mitsumasa Kimata, Masahiro Hasegawa2012 Volume 49 Issue 3 Pages 171-176
Published: March 10, 2012
Released on J-STAGE: March 22, 2012
JOURNAL FREE ACCESSThe hydrogen production was carried out by the agitation of dispersed waste aluminum fine powders in water. A magnetic stirrer was used for agitation of the mixtur in a triangle flask. The waste fine powders from the arc spraying and the plasma spraying were used as aluminum source. In the experiment, reaction temperature, number of revolutions and the size and shape of magnetic stirrer bars were changed. The shape of the waste aluminum fine powders was observed by a scanning electron microscope. Crystal structure was investigated by powdery X-ray diffraction. As a result, the hydrogen amount of production changed by different waste aluminum fine powders at the same agitation condition. It was found that the powder after the reaction with the water formed larger size aggregates and generated a lot of aluminum hydroxide. In addition, agitation speed and the size of magnetic stirrer bars had a large influence on the production of hydrogen.View full abstractDownload PDF (692K) -
Kazuki Asai, Keisuke Naganawa, Takamasa Mori, JunIchiro Tsubaki2012 Volume 49 Issue 3 Pages 177-183
Published: March 10, 2012
Released on J-STAGE: March 22, 2012
JOURNAL FREE ACCESSParticle assembling state in suspensions prepared by different ways was numerically characterized by direct observation method. The aqueous suspensions of alumina powder were prepared by ultrasonication and ball milling. The particle assembling state was characterized by settling test and particle size measurement in addition to the direct observation. From the comparison, the particle images in a suspension getting by the direct observation method can much more distinguish coarse aggregates from primary particles than the other ways. And the black and whiteness of the particle images were classified into 256 steps. The mean values and standard deviations of the black and whiteness distributions were calculated. The variation coefficient determined by the standard deviation over the mean value can show the existence of coarse aggregates that were not ground or re-aggregated.View full abstractDownload PDF (1143K) -
Kunikazu Moribe, Aiko Nagai, Yumi Hagiwara, Waree Limwikrant, Kenjirou ...2012 Volume 49 Issue 3 Pages 184-190
Published: March 10, 2012
Released on J-STAGE: March 22, 2012
JOURNAL FREE ACCESSEffect of dicarboxylic acids : malonic acid (MA), succinic acid (SUA), and glutaric acid (GA), on the preferential cocrystal formation with carbamazepine (CBZ) was investigated. Stoichiometries of CBZ / MA, CBZ / SUA and CBZ / GA cocrystals formed were 2 / 1, 2 / 1 and 1 / 1. When CBZ / SUA ground mixture (GM) was coground with MA, CBZ / SUA cocrystal still remained, i.e., no exchange reaction occurred. On the other hand, exchange reaction occurred when CBZ / MA GM was coground with SUA. CBZ / SUA cocrystal was formed by ternary cogrinding of CBZ, MA and SUA. In CBZ, MA and GA system, preferential cocrystal formation was observed for CBZ / GA. The results of cryogenic cogrinding suggested that preferential CBZ / GA cocrystal formation was due to the stable and rapid crystallization. Preferential CBZ /GA cocrystal formation was assumed when CBZ, SUA and GA ternary cogrinding was performed. Structure and stability of cocrystal, mechanism of cocrystal formation and grinding energy affected the preferential cocrystal former exchange reactions.View full abstractDownload PDF (730K) -
Hirohisa Takeuchi, Hideya Nakamura, Satoru Watano2012 Volume 49 Issue 3 Pages 191-200
Published: March 10, 2012
Released on J-STAGE: March 22, 2012
JOURNAL FREE ACCESSNumerical modeling of individual particle motion and fluid flow in an impact pulverizer was conducted using a Computational Fluid Dynamics (CFD) - Discrete Phase Model (DPM) coupling model. The impact pulverizer consists of high-speed rotating hammers and a static concavo-convex stator. Influences of the rotor geometries on particle impacts against stator walls were investigated. It was found that particles in the impact pulverizer were accelerated by the fluid drag force caused by the rotating hammers but not by the impact force from the hammers, resulting in impacts against walls of the static stator. Velocities and frequencies of the impacts between particles and walls of the static stator were analyzed under various number of hammers and clearances. As the number of hammers increased, the velocity and frequency increased because velocity of the fluid in circumference of the grinding chamber increased. The number of particle impacts against walls of the static stator decreased with an increase in the clearance. The impact energy which was calculated from the velocity and frequency of the particle impacts has the similar tendency with the experimental ones.View full abstractDownload PDF (1024K) -
Yuki Tsunazawa, Chiharu Tokoro, Shuji Owada, Mikio Sakai, Shinsuke Mur ...2012 Volume 49 Issue 3 Pages 201-209
Published: March 10, 2012
Released on J-STAGE: March 22, 2012
JOURNAL FREE ACCESSThe mechanism of part detachment and board breakage process in a drum-typed impact mill to recover valuable metals by removing components from printed circuit boards (PCBs) was investigated. Experimental results using test PCBs showed that parts detachment was enhanced by the increase of input number of PCBs in the mill and board breakage was enhanced by the increase of rotational speed of the agitator. DEM simulation results using spherical particles model showed that board breakage was achieved by the collision of boards with drum wall and agitator, and part detachment was achieved by the interaction between PCBs.
To simulate part detachment and board breakage process more briefly, particle-based rigid body model, in which model PCB geometry was constructed consisting of bonded particulates, was included to DEM simulation. Simulation results showed that board breakage was obtained from the impact of boards with the drum wall and part detachment was obtained from the collision of the boards with each other. These simulation results were successfully corresponded to experimental observations.View full abstractDownload PDF (928K)
Technical Note
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Norihiko Yagi, Yoshihiro Satoh, Yasutake Mori2012 Volume 49 Issue 3 Pages 210-215
Published: March 10, 2012
Released on J-STAGE: August 05, 2015
JOURNAL RESTRICTED ACCESSSilica sand is widely used as a building material and as raw material for glass, but it is necessary to control the particle size or the particle size distribution of silica sand depending on the industrial field applied. It is important to develop a technique to design particle size and to apply a scale-up method for the comminution and classification processes. In this study, a simulation was conducted by applying parameters of comminution kinetics and the partial classification efficiency equation to closed-circuit grinding process. A scale-up technique was established from the relations between the parameters of the comminution kinetics and the mill diameter. In this way, we could obtain the required product size distribution by this simulation method and this scale-up technique.View full abstractDownload PDF (605K) -
Natsuki Takemoto, Hiroaki Kajiyama, Keiji Yamane, Katsu Matsumoto2012 Volume 49 Issue 3 Pages 216-220
Published: March 10, 2012
Released on J-STAGE: August 05, 2015
JOURNAL RESTRICTED ACCESSCarbon dioxide is absorbed through photosynthesis during growth phase of biomass. Thus, the overall balance of carbon dioxide emissions in this practice can be considered even （i.e. carbon neutral）. Increased utilization of unused biomass and biomass waste is one way of solving the problems of reducing carbon footprint. However, since they have high water content, cost of drying is expensive. It is preventing the practical application.
Theoretically, to improve the drying rate, it is desirable to increase the surface area and reduce the thickness of material. We have developed a technology for efficient and functional drying using comminution technique.View full abstractDownload PDF (557K) -
Takahiro Suzuki, Tomohiro Umeda2012 Volume 49 Issue 3 Pages 221-225
Published: March 10, 2012
Released on J-STAGE: August 05, 2015
JOURNAL RESTRICTED ACCESSPowder foundation contains various types of powders such as thin plates, fine pigments and spherical particles. Pulverization processes of the raw materials have significant effects on cosmetic properties of these powders in terms of the feeling on use and appearance of skin. Dry pulverization process by a jet-mill is a simple method to produce talc powder for matte make-up, which makes compact cake hard. In contrast, thin flake mica particles are produced by a wet-pulverization process exerting high shear stress by use of attritor and mass-colloider mills. To visualize the difference in the cosmetic feeling on use when the powder foundations are applied to the skin, we used low-vacuum scanning electron microscope.View full abstractDownload PDF (731K)
Review
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Fumio Saito2012 Volume 49 Issue 3 Pages 226-231
Published: March 10, 2012
Released on J-STAGE: August 05, 2015
JOURNAL RESTRICTED ACCESSGrinding makes surface area of solid increase with accelerating mechanical activation. This induces mechano-chemical （MC） reaction in the solids at certain level of energy stored in the solid, and its reaction yield improves as the grinding progresses. There have been a lot of investigations on the MC reaction in various materials, but its practical applications have rarely been materialized. The author's group has attempted the highly utilization of grinding operation, aiming its engineering application in terms of recycling, waste treatment and clean technology. Some of them have been introduced in this paper.View full abstractDownload PDF (684K) -
Yoshikazu Kuga2012 Volume 49 Issue 3 Pages 232-241
Published: March 10, 2012
Released on J-STAGE: August 05, 2015
JOURNAL RESTRICTED ACCESSThe aim of this study on grinding is not only to investigate particle size change during the grinding, but also to improve the functional properties of the ground products. Because highly crystalline natural graphite has many types of functional properties, such as a high electrical conductivity, absorption of guest molecules, and excellent lubricant properties due to π-electrons between the lamellar crystal structures, the author has chosen to study the grinding of natural graphite particles. The author aims to investigate the effect of various grinding methods on the functional properties of the products.
The author begins this study by investigating experimentally the effects of a wide variety of gaseous and alcoholic vapors present during milling on the flakiness of ground natural graphite particles and the electrical conductivity of films composed of these products. The author then proceeds to evaluate these particles in negative electrode materials for lithium ion batteries, and in hydrogen storage materials. A new grinding method for both dry and wet processes, which uses graphite intercalation compounds and their exfoliated products to obtain flaky graphite particles as the raw materials mentioned above, has been also proposed.View full abstractDownload PDF (1460K)
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