Optical properties, shrinkage, and crack formation up to 800 °C were studied on TiO₂ and SiO₂ sol–gel films for application to thermal radiation control. Using precursor sols comprising hydrolyzed alkoxides and polymers, high-transparency films were obtained for TiO₂ and SiO₂. However, after heating at high temperatures, TiO₂ films exhibited a slight degradation in transmittance due to light scattering by rutile grains. For both materials film thickness decreased by nearly half by increasing the heating temperature from 130 to 800 °C, giving rise to a much smaller critical cracking thickness than that obtained at low temperatures. Within the maximum thickness of the crack-free films, we fabricated TiO₂/SiO₂ alternating stacks as very near-infrared optical filters that allowed the control of the radiation spectra from a plate heater. The emissivity spectra measured on the film/heater system at 750 °C indicated fair agreement with the designed optical transmittance of the stacks, proving the feasibility of applying sol–gel films to thermal radiation control.

Porosity plays an essential role in the performance of ceramics. In this study, the effects of clay composition and firing temperature on the pore size distribution of ceramics were evaluated by small-angle neutron scattering (SANS) measurements. Compared with quartz-rich pure Kasama clay, a mullite-rich Kasama clay blend had smaller pores after heat treatment. SANS measurements of D₂O-absorbed samples revealed that open pores with sizes ranging from tens of nanometers to about a micrometer contributed to the absorption of water. The closed and open pores coarsened and the total porosity decreased with increasing firing temperature.

Heating conditions of off-line Heat Soak Test have been investigated based on a lot of studies about nickel sulfide defect included in the tempered and heat-strengthened glass products. The temperature of the alpha-beta phase transformation is different with a change of the chemical composition (sulfur content) of the nickel sulfide crystal. In the case that the nickel sulfide includes higher than 35.3 wt % of sulfur component, the temperature of alpha-beta phase transformation continuously changes from 379 to 282 °C. There are several thermal conditions for the off-line Heat Soak Test of the tempered glass. The most reliable heat-treatment condition (260 °C+/−10 °C) has been established in ISO 2065 based on EN 14197-1-2016 in 2017. In the world, a lot of glass manufacturers adopt an old condition (290 °C+/−10 °C) of EN 14179-1-2005 in the off-line Heat Soak Test. In the off-line Heat Soak Test, we must maintain the furnace temperature lower than 270 °C that was specified in ISO 20657-2017 in order to raise the degree of beta-phase transformation of nickel sulfide.

It is crucial to develop calcium phosphate cements with high bone regeneration abilities. This study demonstrates synthesis of porous calcium phosphate cements that are set by precipitating octacalcium phosphate (OCP) using α-tricalcium phosphate (α-TCP) and calcium hydrogen phosphate dihydrate (DCPD). Porous spherical granules composed of α-TCP were mixed with either a DCPD powder or α-TCP/DCPD powder mixture as a binder. Next, an appropriate amount of water was added, and the mixture was kneaded. Notably, employing the α-TCP/DCPD powder mixture reduced the setting time of the cement to about 30 min. Porous cements with macropores and micropores were obtained upon precipitation of OCP. Dissolution rate of the obtained cement was higher than that of cements comprising Ca-deficient hydroxyapatite and hydroxyapatite porous ceramics. Our results suggest that this cement may exhibit excellent bone regeneration ability.

Slip-casting is a shaping technique for producing fine ceramic green bodies by mixing a raw powder with water and a dispersant to form a slurry, which is then poured into a gypsum mold to create a solid shape. Coarse-grained raw powders are less expensive but present challenges in slip-casting owing to faster sedimentation and reduced water retention, prompting the need for thickening agents to improve the process. In this study, cellulose nanofibers (CNFs) are added to a slurry to actualize the slip-casting of coarse-grained alumina (∼3.6 µm) with a sintering additive, and their effect on the castability of the slurry is investigated. The slurry without CNFs consolidates immediately after being poured into a gypsum mold. Thus, it can be concluded that slip-casting is difficult for slurries without CNFs. In contrast, the addition of CNFs to the slurry suppresses rapid water absorption and produces a healthy slip-casted green body. A suitable slurry for slip-casting is investigated by adjusting the volume fraction of alumina powder and the amount of CNFs added to the slurry. Shape forming by slip-casting becomes possible by using the optimized slurry. Moreover, a dense sintered body is produced using the slurry via slip-casting and sintering.

Relaxation analysis has been carried out on charge–discharge cycled SiO-graphite composite anode to evaluate the effect of the cycle process on the relaxation behavior after lithium insertion. From the stage change in Li-GIC during the relaxation period, we measured the migrated amount of Li-ion from Li-GIC into SiO and discussed the contribution of charge/discharge cycles. The amount of Li-ion migration is decreased with the cycle number due to the degradation of SiO, which results in the increased rate constant of Li-ion migration.

A cordierite-mullite saggar was prepared via high-temperature sintering with cordierite, mullite and alumina (α-Al₂O₃) and yellow dextrin as raw materials. The physical properties (i.e., density/porosity, linear shrinkage, ignition loss, bending strength and residual strength), thermal shock resistance and durability of the saggar in the synthesis of Li(Ni_0.5Co_0.2Mn_0.3)O₂ (LNCM) as a ternary cathode material were investigated. The results show that the cordierite-mullite saggar with 12.50 wt % α-Al₂O₃ addition prepared at 1420 °C has the optimum properties (i.e., the bending strength of 11.3 MPa, the residual strength of 8.6 MPa and the residual strength retention rate of 76 % after three cycles of thermal shocks) and a prolonged service life at 1000 °C and 4 h for 20 times. This is because the saggar is attacked by Li₂O to generate LiAlSiO₄ and LiAlO₂ with higher thermal expansion coefficients, and LiAlSiO₄ and LiAlO₂ fill the pores to compact the structure of the permeable layer in the high-temperature synthesis of LNCM. As a result, a protective layer decreases the likelihood of the reaction with coordinate and mullite to increase the durability of the saggar in the high-temperature synthesis of LNCM. However, as the time of erosion cycle further increases (i.e., >20 times), the thermal expansion mismatch between LiAlO₂/LiAlSiO₄ and cordierite/mullite can produce more cracks, declining the mechanical properties of saggar and thus damaging the saggar.

This review presents an advanced methodology for producing silicon nitride (Si₃N₄) ceramics with tailored microstructures and distinctive engineering characteristics. Si₃N₄ ceramics are typically composed of highly complex microstructures, including elongated grains dispersed amidst fine grains and grain boundaries, resulting in excellent mechanical, thermal, and electrical properties. Owing to these unique morphologies, Si₃N₄ with enhanced thermal conductivity and mechanical strength has potential practical industrial applications, particularly in insulated heat-dissipating substrates for power modules. In this review, first, the nitridation parameters for the sintered reaction-bonded Si₃N₄ method, which can be utilized to prepare high-performance Si₃N₄ ceramics, are discussed. Second, details of the dielectric breakdown in Si₃N₄ are introduced, and possible defects are suggested based on the results. Finally, artificial intelligence (AI)-based determination technologies utilizing microstructural images via convolutional neural network models are proposed, demonstrating a relatively high accuracy in the AI evaluation of the bending strength and fracture toughness.

In the design of feldspar–kaolin–quartz system of porcelain clays, norm calculations based on the chemical composition of the raw materials are used to predict the degree of pyroplastic deformation by plotting the ratio of the three components onto an existing contour diagram. However, there is no method to quantify the degree of pyroplastic deformation of a porcelain body clay directly from norm calculations. This study presents a direct method for calculating pyroplastic deformation numbers (PDN) from norm calculation. Two methods of calculating PDN were considered: color map diagram reference and finite element analysis. A study of the relationship between the amount of firing deformation and PDN of the porcelain clay actually used in Mino ware showed a negative correlation. Correlation coefficients (CC) based on color map diagram references ranged from −0.62 to −0.66, and those based on finite element analysis ranged from −0.68 to −0.72. Feldspar as an ore is a solid solution of potash feldspar, soda feldspar, and lime feldspar, and its eutectic point varies with the proportion of minerals it is composed of. When corrected for the co-melting point of feldspar, the CC ranged from −0.69 to −0.74. Porcelain clay products were wet overground from 21 to 275 h to determine the relationship between particle size and fired deformation, with a CC of 0.81. Adding a correction for the particle size of the porcelain clay, the CC ranged from −0.70 to −0.78.

Wollastonite is a natural ore of calcium silicate (β-CaSiO₃), which is used as a ceramic raw material. In this study, we prepared porous wollastonite ceramics by using American and Mexican wollastonite powders which contain different amounts of Mg as a trace component. We investigated sintering behavior and physical property of these porous ceramics. As a result, it was revealed that when wollastonite contains at least 0.5 mol % of Mg, phase transition temperature from β-CaSiO₃ to α-CaSiO₃ increased by about 50 °C. Additionally, temperature-dependent phase transition becomes more gradual. This would be due to a phenomenon of “phase transformation” that solid solution of Mg stabilizes β-CaSiO₃ during firing. Moreover, such transformation also affects bulk density, porosity and pore structure of porous wollastonite ceramics.

Flash events can cause rapid mass diffusion through instantaneous power spikes that occur in electric fields and at temperatures above certain thresholds. Recent research suggests that such mass diffusion caused by the flash event may include athermal effects in addition to Joule heating due to the power spikes. However, this perspective has not been applied to surface diffusion, one of the mass diffusion pathways. This study examines the athermal effect on surface diffusion during the flash event by analyzing the surface morphology variation of material uplift formed after the flash-/thermal-healing of Vickers-indentation-induced microcracks. The results show that the formation of surface facet structures, one of the material uplift surface morphologies, varies depending on the direction of the direct current (DC) electric field. The direction dependence of the facet structure formed on the material up-lifted surface due to the DC electric field is a result of the electric field drift effect. The athermal effects associated with flash events can be considered to exist also in mass diffusion involving surface diffusion.

CeO₂-added Au films were drop-coated on a YSZ film fabricated on an alumina substrate embedded a Pt heater on the back side as sensing electrodes (SEs), and their toluene sensing properties were examined in dry air at elevated temperatures (400–600 °C). The suitable addition of polyvinyl alcohol in the precursor solution for drop-coating improved the roughness of the obtained film. The sensor using a 8 wt% CeO₂-added Au SE showed relatively larger toluene responses at higher temperatures (450–600 °C), and the toluene response of the sensor at 500 °C was the largest (ca. 167 mV to 50 ppm toluene) among all sensors in the whole temperature range. The toluene-sensing mechanism of the sensors was discussed on the basis of the mixed potential theory. In addition, we explained that the mixed potential appeared at the interface between SE and gas [SE(Au/CeO₂)/gas] in the SE layer as well as the interface on the YSZ (SE/YSZ/gas) in this study.

Biomineralization is a biochemical process forming biominerals under mild conditions. Although many studies have explored nucleation to crystal growth mechanisms of bioinorganic matter, no universal principle has been established. Herein, four topics related to biomineralization are described: (1) molecular, structural, and functional designs of peptide-based templates for mineralization; (2) structural control mechanisms for inorganic matters; (3) functional modification of organic–inorganic hybrid materials; (4) functional hydrogel fabrication by applying the structural control mechanism inspired by mineralization. The described studies provide significant breakthroughs for improving the functions of organic–inorganic hybrid materials utilizing mineralization-inspired environmentally friendly processes and for the fabrication of functional organic polymer-based materials by mineralization-inspired structural control techniques.

The ability to freely control the performance of ceramics through post-synthetic treatment would be a seed of innovation for various applications. Zeolites, a class of porous ceramics, have regular pores of molecular size and are used as catalysts, adsorbents, and ion exchangers. The control of zeolite composition and pore characteristics by post-synthetic treatments such as steaming has been known, but is still under development, including for target zeolites, more simple methods, achievement of uncharted properties, and so on. In this review, the concept of ‘pore-filler stabilization’ has been developed and utilized to achieve high performance in zeolites, which was previously thought to be impossible.