International Journal of Applied Ceramic Technology最新文献

3 mol% yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP)/TiSi₂ composites reinforced with aluminum oxide (Al₂O₃) were synthesized by vacuum sintering. This case investigated the effects of Al₂O₃ content ranging from 0 to 10 wt.% on the microstructure, mechanical, and electrical properties of 3Y-TP/TiSi₂ composites. According to the results, the addition of Al₂O₃ hindered the densification of the material, resulting in a deterioration in the relative density of composites. On the contrary, the hardness, flexural strength, and average grain size of the conductive phase increased. The maximum value of hardness and flexural strength was 88.70 HRA with 7.5 wt.% Al₂O₃ and 635.45 MPa with 10 wt.% Al₂O₃, respectively. In addition, the addition of Al₂O₃ increases the ratio of grain size between the conductive and insulating phases in composites, leading to a decrease in the percolation threshold and a reduction in resistivity from 4.00 to 1.60 × 10⁻³ Ω·cm with increasing Al₂O₃ content. In conclusion, Al₂O₃ reinforced the comprehensive mechanical properties and optimized the electrical properties of composites by changing the microstructure of the material.

Solid waste recycling plays a crucial role in environmental protection and energy conservation. This study explores the impact of the modulus of the alkaline activator on the dry density, water absorption rate, thermal conductivity, electromagnetic wave absorption, and compressive and flexural strength of rice husk ash (RHA)-foamed composites. Additionally, the foamed composite's micropore structure and hydration characteristics were characterized. For the first time, the study reveals the correlation between the pore structure, hydration products, and hardening properties of alkali-activated RHA-foamed composites. The study found that decreasing the modulus of the alkaline activator increased the amount of OH⁻ ions available in the gel, and the number of micropores (r ≤ .1 µm) in the foamed composites increased from 7.1903% to 21.3156%. This resulted in the refinement of pore sizes and optimization of heat transfer paths. Meanwhile, increasing the C–S–H gel composition in the hydrated products improved its compressive and flexural strength. When the alkali modulus reaches 1, 28 days foamed composites display compressive strength of 8.33 MPa and thermal conductivity of .1404 W/(m·K). Furthermore, the superior pore structure improved the electromagnetic wave absorption of the foamed composites, yielding a reflection loss value of −12.02 dB.

Ceramic components often fail by a brittle fracture mode during the service process. Various factors can affect the fracture properties of ceramics. Experimental methods are usually used to investigate fracture behaviors. However, they give a composite result and the contribution to fracture from each factor is not clear. In the present work, a micromechanical model is developed to quantitatively characterize the fracture properties of ceramics at elevated temperatures. The control method for the microstructures of ceramics is proposed based on the Voronoi diagram. The temperature-dependent surface energy model of ceramics is revised by considering the effects of thermal decomposition and phase transformation. The interface energies at different temperatures are obtained by the inversion method. The criterion for crack propagation of ceramics at elevated temperatures is developed based on the G-criterion. The effects of temperature, grain size, grain size distribution, and grain boundary phase thickness on the fracture behaviors of silicon nitride are studied numerically.

A simple one-step hydrothermal process was employed to develop a favorable class of materials toward energy storage devices such as supercapacitors. The electrode material was characterized using state-of-the-art techniques, along with electrochemical parameters, including galvanostatic charge–discharge, electrochemical impedance spectroscopy, and cyclic voltammetry, toward investigate energy storage behaviors, such as specific capacitance (C_sp), power density, and energy density. Scalable Bi₂S₃ nanorods deposited on eggshell membrane electrodes (ESMEs) exhibit a much greater C_sp of 580.61 F/g on 1 A/g. Calculated energy densities are 29.3, 22.7, 18.8, and 15.0 W h/kg, whereas the power densities are 263.1, 349.3, 663.1, and 870.0 W/kg at 1, 2, 5, and with 10 A/g, respectively. These impressive conclusions are attributed to the enhanced electroactive surface area of Bi₂S₃/ESME (625 cm²). The unique structure of these materials, featuring a substantial surface area (78.3 cm²/g), contributes to this enhanced performance. The findings of this study could inform new strategies for boosting the performance of future applications.

In this paper, test results for woven ceramic matrix composites (CMCs) based on an oxide matrix and oxide fiber are presented. Stress–strain curves under cyclic loading for different in-plane fiber orientations as well as strength values for different fiber orientations under tension and compression and under pure shear are presented. Based on the experimental data, a nonlinear damage model is derived which allows to determine the progressive degradation of the elastic moduli and the nonelastic remanent strain in a satisfactory manner. It has been implemented into the finite element code ANSYS and shows excellent convergence behavior. To predict the failure of CMC components, the failure mode concept proposed by Cuntze is extended to include friction effects due to tension and compression on the in-plane shear failure mode. The predicted failure onset matches the experimental data very well, whereas existing models like the max-stress or the Tsai–Hill criteria show larger deviations.

Three kinds of Si₃N₄-based ceramic tools (single-phase Si₃N₄, Si₃N₄/(W,Ti)C, and Si₃N₄/(W,Ti)C/Ni) were fabricated by microwave sintering. The phase composition, toughening mechanism, mechanical properties at room and high temperatures (800°C), and cutting performance of Si₃N₄-based ceramic tool materials with different additives were investigated. The results showed that the addition of (W,Ti)C and Ni had a significant effect on improving the mechanical properties at room temperature, although it reduced the phase transition conversion rate of Si₃N₄. Si₃N₄/(W,Ti)C tools had good high-temperature stability, while Si₃N₄/(W,Ti)C/Ni tools had a decrease of about 31.6% in high-temperature hardness and a decrease of 13.7% in high-temperature flexure strength. Under the premise of ensuring a certain level of fracture toughness, high-temperature hardness is the main influencing factor on the cutting life of cutting tools. The Si₃N₄/(W,Ti)C tools exhibit superior cutting performance whose cutting life reaches to 50.67 min which was 1.37–3.27 times longer than the other two ceramic cutting tools at the same cutting parameters when continuous dry cutting T10A. In addition, high-temperature flexure strength limits the choice of cutting speed, and lower high-temperature flexure strength can lead to rapid tool failure.

In this study, the hydrothermal corrosion behavior of zirconium nitride (ZrN) ceramics used as a surrogate nuclear fuel of UN, which were added with different amounts of CrN/Cr₂N (0, 10, 20, and 30 vol.%), was investigated with the objective of increasing the loss-of-coolant accident (LOCA) tolerance of pressurized water reactor fuel. The ZrN-based ceramic samples with a density exceeding 98% were fabricated by using a spark plasma sintering system at 1700°C and applied stress of 30 MPa. Following 30 min of hydrothermal corrosion at 300°C, the oxidation layer thickness of pure ZrN ceramics was 9.11 ± 1.96 µm, whereas that of 30 vol.% CrN/Cr₂N-ZrN was only 1.23 ± 0.3 µm, which indicated that CrN/Cr₂N offered an excellent protection effect for ZrN. This work can, thus, provide engineering design guidance for the UN with high uranium density to increase the LOCA tolerance of current nuclear power generation systems.

Despite the successful preparation of high-performance calcium aluminate cement-bonded castables, occasional explosions have been reported. The occurrence of castable explosions is commonly attributed to water vapor overflow retarding and vapor pressure generated by rapid temperature rise. To enhance the explosion resistance of castables, methods such as incorporating various fibers (e.g., polypropylene [PP], polyethylene [ED], aramidic [Par], and steel fibers) have been proposed. However, limited studies have investigated the impact of fiber content on pore structure and fracture behavior of castables. This study aims to assess the influence of different PP fiber contents on comprehensive properties of castables. The explosion resistance was evaluated in conjunction with air permeability and pore structures, and fracture behavior was tested through wedge splitting tests at both room temperature and elevated temperatures. Results indicated that the addition of PP fibers significantly improves air permeability thus enhancing anti-explosive capabilities. Simultaneously, the combustion of fibers resulted in the formation of residual pores, which contributed to an enhanced resistance against stress-induced damage.

In this work, MgO-MgAl₂O₄ ceramic filters were fabricated from microporous MgO powder and α-Al₂O₃ micro-powder, in which microporous MgO powder was prepared using Mg(OH)₂ as initial raw material. With the α-Al₂O₃ micro-powder content increased from 0 to 15 wt%, the tight packing and reaction sintering between MgO microparticles and Al₂O₃ microparticles promoted the formation and growth of magnesium aluminate spinel necks, reduced the apparent porosity of ceramic filter skeletons, decreased the pore size, and improved the strength of the filters. When the α-Al₂O₃ micro-powder content further raised to 20 wt%, the thermal mismatch between MgO microparticles and spinel microparticles caused a small amount of crack generation, which lowered the strength of the filter. Besides, after introducing the α-Al₂O₃ micro-powder, more spinel necks were produced due to a small amount of MgO solid dissolved in the spinel lattice during the thermal shock test, which enhanced the thermal shock resistance of the filters. When the α-Al₂O₃ micro-powder content was 15 wt%, the filter had excellent comprehensive performance, the bulk density and apparent porosity of the filter skeleton were 3.09 g/cm³ and 10.7%, and the compressive strength before and after thermal shock test was 3.48 and 3.70 MPa, respectively.

Semi-rebonded periclase-chromite refractories are commonly utilized in the working lining section of the molten pool in oxygen-enriched top-blowing furnaces for nickel production. Its resistance to nickel slag corrosion determines the safety and service life of the melting furnace. The composition of nickel slag influences the corrosion resistance of semi-rebonded periclase-chromite refractories. By comparing and analyzing specimens corroded by primary and modified nickel slag, the influence mechanism of w(CaO)/w(SiO₂) variations on corrosion resistance of semi-rebonded periclase-chromite refractories was clarified. The results show that a spinel isolation layer is preferred to form at a lower w(CaO)/w(SiO₂) ratio (< 0.576) and enhance the corrosion resistance of semi-rebonded periclase-chromite refractories. As the ratio increases, the slag viscosity falls and the corrosion products contain larger levels of Ca₃Cr₂Si₃O₁₂ and Ca₃MgSi₂O₈, which prevent the creation of the isolation layer and establish a conduit for Ca²⁺ and Si⁴⁺ transport and reaction into the interior of the refractory.