Preparation of boehmite-silica composite particles using heterocoagulation was studied to improve the packing ratio and flowability of the particles used as fillers and flame retardants in resins. By measuring the zeta potential of each particle, silica showed a negative charge at pH > 2, and boehmite showed a positive charge at pH < 9. Therefore, mixing of each suspension of silica and boehmite prepared at pH 4 successfully produced boehmite-silica composite particles by heterocoagulation. We used two different silica particle sizes. Using smaller silica particles, composite particles uniformly coated with silica were obtained. The composite particles showed excellent fluidity in liquid paraffin, which suggested improved packing ratio.

This study is aimed to develop a beneficial use of disposed seashells. Sanriku region in Iwate prefecture has an issue of disposals of seashells. In this study, we mechanochemically ground seashells under dry or wet conditions. We used a planetary ball mill, a tumbling ball mill, and a converge mill as mechanochemical grinding machine. After the grinding, we examined the heavy metal absorbencies of the ground materials, and of the compounds with seashell-origin hydroxyapatite (HAP). As a result, followings were found out: 1) When seashell-origin hydroxyapatite was used, it showed adequate heavy metal absorbency (Cd, Pb). 2) When mechanochemically ground scallop seashells without HAP were used, it showed adequate heavy metal absorbency (Cd, Pb). 3) When the scallop seashells are ground for long time under dry condition (mechanochemical grinding), the material tends to be amorphous, and its heavy metal absorbency becomes greater.

A new simulation approach using Advanced Distinct Element Method (ADEM) was proposed to predict the compression behavior and the characteristic of the compact. Relationship between compression load and compressive strength of compact have been analyzed. The breakage behavior and discrete motion of particles during compression was simulated by ADEM. ADEM parameters represent the property of samples, it was determined to fit the experimental results of load-displacement curve obtained by single particle compression test. Internal structure of compact was measured by X-ray CT imaging, information of particle breakage and density distribution was obtained. High density compact could make as a result of high compression load, on the other hand, compressive strength of compact decrease when the compression load was much high. There was optimum condition to obtain the tough compact. Simulation analysis could visualize the compression behavior of compact, fine powder ratio suggest the optimum compression load for powder compact.

The author has investigated the serial research on grinding coupled with mechanochemistry for different materials since 1990. The materials used in this research was varied from inorganic to organic materials, and it was found that the characteristics have been changed into unique and peculiar ones which are sometimes far from the starting samples. It seems to be a series of strange happenings done without heating, which have never been seen before.

This paper has picked up several topics such as the results on the phase transformation by grinding, followed by mechano-synthesis of functional materials such as photo-catalysts by doping the non-metal element, decomposition of halogenated resin. Finely the novel processes for recycling of wastes and recovery of energy from biomass have been introduced.