The purpose of this study is to investigate the effects of acoustic streaming and acoustic radiation force on particles motion in an ultrasonic standing wave. A flexural vibration plate with 4 nodes was designed, and it was shown that the amplitude at the antinode is proportional to the voltage. This means it is possible to conduct experiments with any amplitude. After confirming that a standing wave field was generated in closed space, an experiment was carried out to visualize acoustic streaming. Eight vortices were observed in the horizontal direction, indicating a Rayleigh acoustic flow. In addition, a vortex in perpendicular direction against the plate was generated when the height between vibration plate and acrylic surface was set at half wavelength. Then two vortexes were obtained at a wave length for the height. Simulations for acoustic pressure and streaming agreed with this experimental result. Finally, simulations on particle motion showed that acoustic flow dominates when particle diameter is less than 20 μm. On the other hand, the motion of over 20 μm particle is influenced by acoustic radiation force.

This review presents new techniques for the measurement of ceramic slurries. First, we have developed a scanning electron-assisted dielectric microscope (SE-ADM) system with energy-dispersive X-ray spectrometry (EDS) that enables direct observation and elemental analysis of nanoparticles in solution. This system facilitates the understanding of alumina particle dispersion states in solution, binder distribution, and silica and magnesium particle bonding states. Furthermore, we demonstrate a dynamic approach to evaluate adsorptive interactions between ceramic particles and polymeric binders entangled in a slurry by utilizing differential centrifugal sedimentation (DCS). The settling of particles under a centrifugal force field exerts significant viscous resistance on the adsorbed binder, leading to its detachment, influenced by particle size and density. This behavior directly reflects the particle-binder interactions, and detailed DCS spectrum analysis enables the quantitative assessment of nano-Newton-order adsorption forces.

Calcium carbonate nanoparticles are widely used in various composite materials across industrial sectors. However, previously synthesized calcite nanoparticles have typically been rhombohedral with an aspect ratio of ~1. This study investigates the microscopic evolutions of particle morphologies during the formation of calcite rhombohedral nanoparticles. By better understanding these changes, methods involving the addition of Ca(OH)₂ and Mg(OH)₂ have been developed to produce high-aspect-ratio 1D chain-like particles. Controlling the primary particle morphology significantly enhances solid-liquid separation in slurries after liquid-phase synthesis and improves the mechanical properties when these particles are used as fillers in composite materials.

The flexible metal-organic frameworks (MOFs), which are a new type of porous material, exhibit unique adsorption behavior, and are expected to have a wide range of applications. However, to overcome the issue of low handling performance of flexible MOFs, it is necessary to establish a molding process. Although it is predicted that the flexible MOF particles and their aggregate structure should strongly affect the molding process, the effect on the particularly unique adsorption behavior is still unknown. In this study, the effect of the aggregate structure of flexible MOF particles on the uniaxial compression process was investigated experimentally and numerically. It was demonstrated that hollow-structured aggregates maintained the best adsorption properties. In addition, numerical analysis revealed that the force applied to the particles was reduced in hollow-structured aggregates. These would be useful results for the practical application of flexible MOF particles.

Cerium oxide nanoparticles were synthesized using the Forced Thin-Film Type Reactor (FTFR). The precipitation solution was changed from aqueous sodium hydroxide to ammonia solutions. By adjusting the mixing ratio of trivalent and tetravalent cerium ions in the solutions and varying the cerium ion concentration, the shape of the particles varied from spherical to truncated octahedron and irregular shape to cuboidal to truncated octahedral. It was estimated that the change in particle shape could be attributed to the difference in the concentration of dissolved oxygen and hydroxide ion in each solution.