A method for evaluating the uniformity of a small volume of the components of four kinds of zirconia and silica powder mixture in the range of 10^-3-10^-5mm³ was investigated using Micro Fourier transform infrared (micro-FTIR) reflectance spectrometry. The respective ten micro-FTIR reflectance spectra (spot size is 250×250μm²) of different locations in a sample were measured, and the relative standard deviation (RSD) of the peak height ratios (1100cm^-1: assign to Si-O vibration/600cm^-1: assign to Zr-O vibration) was calculated for each sample. If the RSD value was below the error that accompanied the measuring method (about 3%), the sample was regarded as uniform. The above operation was repeated with diminishing spot size (80×80 and 25×25μm²) for every sample, and the relationships between the RSD values and measuring volume which was estimated from spot size were obtained. The least volumes (regarded as uniform) were obtained for each sample, respectively.

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Wet milling by a multi-ring media mill was carried out for aqueous slurries of Mg(OH)₂ and TiO₂ powder mixtures in the concentration range from 6.9wt% to 50wt%. Rings used as grinding media were made of partially stabilized zirconia (ZrO₂) or polyoxymethylene (POM). Products were characterized by TG-DTA, X-ray diffractometry and EPMA. ZrO₂ contamination in the product was determined by X-ray fluorescence analysis. The temperature of endothermic peaks, attributed to the dehydration of OH group, remain almost unchanged regardless of slurry concentration but decreased with increasing compressive force exerted by grinding rings. The homogeneity of the product is correlated with the temperature of exothermic peaks above 1100K due to the crystallization of MgTiO₃, but not with the endothermic peaks around 650K. The increase of the slurry concentration increases the homogeneity of the product, facilitating the formation of single phase MgTiO₃ on subsequent heating. The increase of the compressive force of grinding rings brings about not only the homogeneity but also the phase purity of MgTiO₃.

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The fluidized bed granulation is used widely in the manufacturing process of solid drug products. It is known that the optimum condition of granulation is not decided simply because of the complexity of the operation factors. In this study, the effects of manufacturing factors on the physical properties of granules are investigated to clarify the granulation mechanism. From the experimental results, it is found that the average particle size is determined by the moisture content of the granule. From the theoretical consideration of the physical properties of the granule, a granulation model is proposed. The granule density and bulk density are found to be simulated by this granulation model. At the same time, the scale effects of experimental apparatus on the physical properties of the granule are discussed.

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A system has been developed and evaluated to measure the size distributions of submicron powders suspended in air instead of in liquid. Aerosol particles were generated by drying after the boiling of atomized droplets of submicron perfluorocarbon particle suspensions. The size distributions of several submicron particles of the generated aerosols were measured by a DMA (differential mobility analyzer) and CNC (condensation nucleus counter) system which are widely used and well established in aerosol research. The results were compared with those obtained by the electron microscope and centrifugal sedimentation methods. It was found that the present method could generate an aerosol in which particles were dispersed into primary ones.

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