Electrophoresis of particles by applying an electric field to a colloidal suspension allows simultaneous manipulation and shaping of particles. A film forming process utilizing the electrophoretic phenomenon of charged particles in a liquid is called “electrophoretic deposition (EPD)” and is used for powder coating. The main difference between the EPD process and other colloidal processes is the coexistence of electrode reactions, ie electrochemical reactions that occur at the interface between the electrode and the electrolyte solution. The applied electric field in the EPD method plays an important role not only in the electrophoresis of charged particles but also in controlling the coagulation mechanism and film quality. This paper introduces the principle of the EPD process considering the electrode reaction and an example of the functional film formation process.

We have established an evaluation method based on optical coherence tomography (OCT), which uses light interference, as a method for three-dimensional in-situ observation of the internal structure of slurries, compacts, and sintered bodies. Nondestructive inspection by evaluating defects inside sintered bodies, dynamic changes in particle sedimentation and drying processes in ceramic slurries, quantitative evaluation of pore structures in dry forming under applied stress, and visualization of internal structures under high temperature in dewaxing and sintering are enabled. This method is expected to be of great help in research and development as an innovative evaluation method that enables consistent and direct observation of structural changes from the micrometer scale equivalent to particle size to the millimeter scale equivalent to bulk materials under a variety of actual environment conditions.

Cesium-tin-bromide perovskite (CsSnBr₃) has focused on as a candidate material for all-inorganic perovskite solar cell and thermoelectric energy converter because of its optical, electrical, and thermal properties. On the other hand, the electrical properties have not been clarified yet because of several inconsistent reports. In this paper, we produced CsSnBr₃ bulk from a melt using the precursor powder prepared by a mechanochemical process. From powder X-ray diffraction analysis, main phase of the precursor was CsSnBr₃ perovskite, and minor impurities were Cs₄SnBr₆ and CsSn₂Br₅. Although main phase of the bulk produced from a melt was CsSnBr₃, small amount impurity, CsSn₂Br₅ was confirmed. From the electrical conductivity (σ_t) measurement, irreversible temperature dependence of σ_t was observed at first time increasing temperature. The conductivity measured from room temperature to 443 K at the first time showed metallic behavior. On the other hand, the temperature dependence is changed into opposite with decreasing temperature. At this operation, σ_t decrease with decreasing temperature. This semiconductor like behavior was found to be reversible after first increasing temperature operation. These results indicate that post anneal as well as production process of CsSnBr₃ would be important to control its electric property.

Hydroxyapatite (HAP, Ca₁₀(PO₄)₆(OH)₂) is a major component of bones and teeth and requires a specific crystal orientation for biomaterial applications. We have developed a method to control the orientation by applying a strong magnetic field during colloidal processing. In this study, we have demonstrated that suspensions with dispersed agglomeration-free nano particles can be produced by beads-milling HAP particles with zirconia beads as small as 0.05 mm. By slip casting in a high magnetic field and sintering using suspensions with dispersed agglomeration-free nano particles, high-density and oriented sintered bodies were successfully fabricated at low temperatures.

Wear properties of high-density Ti₂AlN oriented specimens prepared by slip casting in a high magnetic field followed by SPS were investigated by comparing them with nonoriented specimens. The coefficients of friction were in the range of 0.25 < μ < 0.35 for both oriented and nonoriented specimens at each load, and even without lubrication, low coefficients of friction were observed. The specific wear of the oriented specimens was lower than that of the nonoriented specimens, and the specific wear increased with increasing load. The top surface of the oriented specimen showed less specific wear than the side surfaces, which was interpreted to be due to the layered structure of the plate-like grains. From the sliding marks, a large area of the nonoriented specimen was worn, whereas a large area of the oriented specimen maintained its initial surface condition.