The electrophotographic image quality depends on the triboelectric charge of insulating toner. However, the control of triboelectric charge is difficult because of the insulating nature of toner. In this study, the controllability of charge on the insulating toner was experimentally investigated by using a corona charging system, an electron charging system (contact type), and an electrostatic induction charging system (non-contact type). The charging systems except the contact type electron charging were able to change the toner. The ion charging system changed the toner polarity to negative from positive. Although the toner was charged to the charge saturation level, the saturated value depended on the initial charge generated by the triboelectric charging. The electrostatic induction charging system was able to charge the toner with a high volume resistivity in the range of electrical insulation.

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Nickel fine particle in the order of 0.1μm in size has been prepared by wet chemical reduction of nickel sulfate with sodium hydroxide and hydrazine. The preparation was carried out under stirring and static conditions at a constant temperature. Nickel particles of 0.3-1.0μm in size were obtained by changing the concentration of nickel sulfate, sodium hydroxide and hydrazine with the stirring method. SEM photos show that these particles were agglomerate and composed of primary nickel particles smaller than 0.05μm. The static method, by which nickel hydroxide was generated from nickel sulfate, was promptly reduced by hydrazine, and successfully produced nickel particles of 0.1μm with a sharp size distribution.

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A dark brown liquid with magnetic properties, named “fluid-ferrite”, was synthesized directly by microwave-assisted chemical reaction. The “fluid-ferrite” is a slurry composed of ferrite nanoparticles and organic solvent. Solid ferrite particles are too small to be seen by the naked eye, so that “fluid-ferrite” looks like a liquid. It is stable for a long time without phase separation, and floats perfectly on water. In case of Ba-ferrite synthesis, the main reason for production of “fluid-ferrite” is the suppression of crystal growth of particles. On the other hand, in case of Ni-ferrite synthesis, it is the suppression of agglomeration of nano particles produced in the primary reaction.

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Long-term sedimentation tests were carried out in order to evaluate the effects of solid concentration and dispersant dosage on the sedimentation behavior of alumina slurries. The sedimentation behavior of slurry was observed by using a digital camera for over sixth months. As a result, it was found that the sedimentation behavior of slurry with a dispersant can be classified into four patterns on the basis of the interface formation between supernatant and dense slurry layer in the early stage of sedimentation. Furthermore, a concentration inversion and lean layers were formed from the middle stage of settling in the slurries which did not show a clear interface in the early stage sedimentation. The packing characteristic of slurry was significantly changed at a solid concentration between 10 and 20vol%.

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The void fraction in a powder packed bed is not uniform and the vertical distribution of void fraction varies with the packing method. However, detailed profile of void fraction distribution and effect of packing method on the distribution have not been discussed. Recently, X-ray micro Computed Tomography was developed and applied to the observation of powder packing structure. We utilized X-ray micro CT Scan to measure the void fraction profiles of powder layer formed by piston compression and centrifugal packing. Our experimental results showed that void fraction increases with the depth of powder layer in piston compression while it decreases with the depth of powder layer in centrifugal packing. The theoretical void fraction profiles, calculated by Janssen's equation with boundary condition of each packing method, well expressed the measured voidage distribution by X-ray micro CT scanning.

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A new recycling process of coal flyash exhausted from a coal fired power plant and polymer waste was studied. In this paper, we proposed a novel process to prepare coal flyash/polymer waste composite for a sound absorbing wall. First, granules with diameter of 2.5-5mm or 5-10mm were made from the coal flyash, and then calcinated to improve the strength of granules. During the granulation operation, we also investigated the effect of additive of bentonite on the strength of granules. The surface of granules were coated by mixing the heated granules with the crushed polymer. These coated granules were then heat-molded, and a composite sound absorbing wall was obtained. The conditions and material properties during the process were examined, and the sound absorption coefficient of the composite was evaluated for the application to sound absorbing wall for highway roads.

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In this study, we conducted dry grinding tests of silica glass using a laboratory ball mill with and without methanol as well as wet grinding tests. We found that in the early stage of grinding the dry grinding with methanol reduces the coarse feed particles (1, 180-1, 000μm) at a faster rate than dry grinding without methanol and wet grinding. We also investigated the effect of grinding medium density on the reduction rate of coarse particles with size from 1, 000 to 75μm by conducting dry grinding tests with methanol using alumina or zirconia balls. The zirconia balls were more effective for shortening the grinding time than the alumina balls, whereas the alumina balls lowered the input energy required.

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