Ryutaro Usukawa

Cracks are a phenomenon found in various natural situations, yet they represent a long‐standing challenge as a critical defect in industrial fields. For instance, cracks formed during the drying of colloidal slurries lead to performance degradation and disruptions in processing. Although numerous experimental and theoretical approaches have been explored to understand and control crack formation, its complex mechanisms remain difficult to comprehend systematically. Here, we demonstrate a novel perspective that cracking can be understood through the thixotropic behavior of slurries. The elastic structural recovery that determines thixotropy is quantitatively evaluated using aqueous colloidal slurries with alumina particles as a model. Furthermore, this elastic force is shown to be highly sensitive to changes in particle dispersion. A key finding is the strong correlation between the elastic structural recovery of slurry and crack formation during drying. Based on the multifaceted experimental results, we elucidate the hidden physics of thixotropy as a crucial indicator of durability against drying‐induced stresses.

High-resolution observation and elemental analysis of various particles in solution are important in the fields of materials, analytical chemistry, and industrial applications. Analysis of slurries of raw materials is essential for the development of highly functional materials. Recently, we have developed an SEM-based scanning electron assisted dielectric microscope (SE-ADM), which can directly observe biological samples and organic materials in aqueous solutions. Here, we have developed an SE-ADM system with the addition of energy-dispersive x-ray spectrometry that enables direct observation and elemental analysis of nanoparticles in solution. Using this system, we were able to directly observe and conduct elemental analysis of ceramic slurries and to clarify the dispersion state of alumina particles in solution, the distribution of binder, and the bonding state of silica and magnesium particles. Furthermore, our system can be applied to diverse liquid samples across a broad range of scientific and industrial fields, for example, nanotubes, organic specimens, batteries, and catalytic materials.