Alumina ceramic slurry with large solid content and small viscosity could be used in the additive manufacturing process of material extrusion (MEX) and photo-polymerization (PPM). Alumina ceramics powder and 1,6-Hexanediol diacrylate were adopted as prepolymer monomer for ceramic slurry, and typical surfactants such as polyvinylpyrrolidone K10, polyvinylpyrrolidone K15 and oleic acid (OA) were adopted to modify alumina ceramic particles, and then rheological properties of the slurry and formality of built parts were deeply evaluated. The results showed that slurry with OA with the concentration of 0.15 wt % presented better comprehensive properties than the other surfactants, and the viscosity of the slurry with 81 wt % alumina modified by 0.15 wt % OA was 8.88 Pa·s under shear rate 30 s⁻¹, and the slurry had been successfully applied for ceramic green body molding by the MEX-PPM method, and the deformation rate was 0.25 %, while the volume density of ceramic sintered body was 3.78 g/cm³. In conclusion, the use of suitable surfactant modification can improve the mechanical properties of the material and expand the scope of application.

Bismuth potassium titanate (Bi_1/2K_1/2)TiO₃ with an A-site complex perovskite structure is regarded as a promising lead-free ferroelectric/piezoelectric material. Studies on the fundamental properties of (Bi_1/2K_1/2)TiO₃ have, however, been faced with difficulties in fabricating dense and phase-pure (i.e., “high-quality”) bulk ceramics caused by its low melting point and the volatility of Bi and K. This paper reviews our findings on the fabrication process and fundamental properties of such high-quality (Bi_1/2K_1/2)TiO₃ ceramics. After a brief survey on the crystal structure and physical/chemical stability of (Bi_1/2K_1/2)TiO₃, our fabrication process of (Bi_1/2K_1/2)TiO₃ ceramics utilizing the hydrothermal synthesis method is described. Then, the phase transition behavior of (Bi_1/2K_1/2)TiO₃ is discussed based on the electrical and electromechanical responses of the high-quality ceramic samples. The last part of this paper presents two examples of compositional modifications of (Bi_1/2K_1/2)TiO₃ ceramics aiming at developing dielectric and piezoelectric materials for use in capacitors and actuators.

High-entropy alloys (HEA) are characterized by unique composition design concepts and excellent performance. As binders for cermet materials, they have been studied in recent years and have shown broad application prospects. In this study, the microstructure, mechanical properties and high-temperature oxidation behavior of Ti(C,N)–TiB₂-HEA composite cermets with different HEA binder contents are investigated. The experimental results indicate that as the HEA content increases from 6 to 14 wt.%, the pores of the composite cermets gradually decrease, and the grain size first increases and then decreases. The hardness of the composite cermets gradually increases, and the bending strength and fracture toughness first increase and then decrease. The highest hardness, bending strength and fracture toughness values are 2008.6 HV₁₀, 727 MPa, and 7.9 MPa m^1/2, respectively. The composite cermets with 14 wt.% HEA binder exhibit superior oxidation resistance. This is because the internal metal atoms diffuse to the surface, which will consume more oxygen and form a dense oxide layer. The diffusion of oxygen to the internal non-oxidized parts will be effectively inhibited. In addition, cracks appear in the oxide layers at 1000 °C. As the HEA binder content increases from 6 to 14 wt.%, the cracks gradually disappear during the oxidation process and are replaced by an Al₂O₃ layer.

Magnesium oxychloride cement (MOC) cement was prepared using magnesia derived from the calcination at 400–900 °C of magnesium-residue from the production of LiCO₃ from salt lake brine. The setting time, compressive strength, hydration course and pore distribution of MOC cement were measured, and the effects of additives and mineral admixtures on their mechanical properties and water resistance were studied. It was found that lower calcination temperature and high molar ratio of a-MgO/MgCl₂ are more conducive to the setting and hardening and mechanical properties of MOC cement. However, adding KH₂PO₄ and mineral admixtures to MOC cement can only improve its short-term (3 days) water resistance, and cannot completely solve the problem of poor water resistance of MOC.

Phase pure HfB₂–SiC powders were efficiently synthesized via microwave/molten salt assisted boro/carbothermal reduction (MMS-BCTR) method by using HfO₂, SiO₂, activated carbon and B₄C powders as raw materials, and NaCl–KCl as a molten salt medium. The effects of mass ratio of salt to reactant (m_s/m_r), holding period, reaction temperature and B₄C content on the phase composition and microstructure of the synthesized HfB₂–SiC powders were investigated. The results showed that the optimal molar ratio of HfO₂/SiO₂/B₄C/C was 3.0:1.0:3.2:4.0, m_s/m_r was 2.0, and reaction temperature and holding period were respectively 1250 °C and 20 min. Rod-shaped HfB₂ and irregular SiC particles were uniformly distributed in the products, the former with a length of 0.5 µm and a diameter of 300 nm exhibited a single-crystal structure with a preferred growth along the [100] direction, while the latter had a particle size of about 300 nm.

In this study, we successfully synthesized Li_xLa_(1−x)/3Nb_0.80Ta_0.20O₃ solid solutions with different Li concentrations (x = 0.00–0.30) by a solid-state reaction. With an increase in x, the crystal structure of Li_xLa_(1−x)/3Nb_0.80Ta_0.20O₃ initially changed from orthorhombic (0.00 ≤ x ≤ 0.05) to tetragonal (0.10 ≤ x ≤ 0.25) and then from tetragonal to cubic (x = 0.30). Grain sizes of Li_xLa_(1−x)/3Nb_0.80Ta_0.20O₃ increased with an increase in x. Moreover, densified Li_xLa_(1−x)/3Nb_0.80Ta_0.20O₃ pellets were obtained. Li_xLa_(1−x)/3Nb_0.80Ta_0.20O₃ with x = 0.10 showed the highest ionic conductivity of 7.78 × 10⁻⁵ S cm⁻¹ at room temperature, which decreased with an increase in x from 0.10 to 0.30. Activation energies of Li_xLa_(1−x)/3Nb_0.80Ta_0.20O₃ were in the range of 0.31–0.38 eV, which increased with an increase in x.

Magnesium phosphosilicate cement (MPSC) is generally composed of magnesium oxide, phosphate and silicate, and the admixture is generally borax to extend the setting time. In the preparation of traditional magnesium phosphate cement (MPC), reburned magnesium oxide is generally used. In this study, light-burned powder calcinated with borax will be used instead of reburned magnesium oxide to prepare MPC. The calcination temperature range is 1000–1200 °C and the holding time is 2 h. This paper explores the influence of magnesia reactivity at different calcination temperatures on the performance of MPSC, including setting time, electron microscope, heat of hydration, phase composition and strength development. The results show that borax can significantly reduce the reactivity of magnesia. Experimental data shows that as the reactivity of magnesia increases, the mechanical properties of MPSC cement become better, and the porosity will also decrease. However, when the reactivity is too high, the cement cannot be formed because of the early setting time.

Flash sintering has attracted much attention as a useful sintering technique that is able to lower the sintering furnace temperature and shorten the sintering time. To further improve this original flash sintering technique, we have developed a technique to facilitate shrinkage at a constant shrinkage rate by controlling the power dissipation during a flash state, which is termed as shrinkage-controlled flash (SCF) sintering. Here, we combine this SCF sintering method with a rapid furnace heating process to shorten the entire sintering process time. Accordingly, we succeed in sintering 3 mol % Y₂O₃-doped ZrO₂ (3YSZ) polycrystals with a high density of 6.05 g/cm³ and a uniform grain size of approximately 0.47 µm with a short sintering time of approximately 40 min. The obtained 3YSZ polycrystals are confirmed to exhibit a Vickers hardness and fracture toughness [by an indentation fracture method] of approximately 1295 HV and 5.3 MPa m^1/2, respectively.