The film formation method utilizing the electrophoretic phenomenon of charged particles in a liquid is called “electrophoretic deposition (EPD)” and is used for powder coating, etc. The main difference between EPD and other colloidal methods is the coexistence of an electrode reaction, i.e., an electrochemical reaction that occurs at the interface between the electrode and the electrolyte. The applied electric field in the EPD method plays an important role not only in the electrophoresis of the charged particles, but also in controlling the aggregation mechanism and film quality. In this paper, we introduce the principle of the EPD method that takes into account the electrode reaction, and an example of its application to ceramic coating that does not require a post-sintering process.

In this study, we investigated how the type of solvent affects powder pulverization and hydrophilicity/hydrophobicity in a wet planetary ball mill. We found that as the viscosity of the solvent increased, the flow of the powder was restricted, improving the pulverization efficiency. The surface properties of the powder were influenced by the ratio of dipole moment to molecular volume. A higher ratio resulted in greater hydrophilicity due to the formation of hydroxyl groups, probably caused by the breaking of surface bonds and the formation of radicals from mechanical energy during grinding. These radicals reacted with water to form hydroxyl groups. However, no increase in hydrophilicity was observed for alcohols with a low ratio, suggesting that hydroxyl groups were not formed and reactions between radicals and alcohols were minimal under these conditions. Further research is needed to investigate this phenomenon.

The effects of additive types and amounts on the slurry properties were investigated with the aim of preparing soft-flocculated slurries of barium titanate and developing a binder-less forming technique for flexible sheets using the prepared slurries. In addition, sheet forming was carried out using the prepared soft-flocculated slurry and the packing fraction and flexibility of the formed sheets were evaluated. As a result, the soft-flocculated slurry was prepared by preparing a well-dispersed slurry using polyelectrolyte and then adding molecules with opposite charges to the polyelectrolyte. The amount of addition at which the slurry had yield stress was attributed to the geometrical structure of the particles and was not affected by the type of additive. On the other hand, the magnitude of the yield stress was influenced by the valence and side chains of the added molecules. Using the prepared soft-flocculated slurry as a precursor, binder-less and highly packed sheets were successfully formed. It was found that there is an optimum value for the additive amount to form flexible sheets.

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.