International Journal of Applied Ceramic Technology最新文献

An applied and empirical compaction fracture resistance parameter, K_COMP, was developed to represent the compression-induced interparticle-comminution response of granular brittle materials (e.g., ceramic or glass particles). The development of K_COMP is an outcome from Part I of this three-paper series. The K_COMP represents a continuum response of compaction fracture resistance and was adapted from established Griffith linear elastic fracture mechanics theory. From that, the K_COMP relates macroscopically applied compressive stress to a corresponding inverse-square-root representative particle size, where the latter is estimated from an entire particle size distribution or specific surface area measurement. The K_COMP value was not constant over a wide range of stresses for all examined brittle granular materials, and this is indicative of a change in the dominant mode of permanent deformation at higher compaction stresses.

Si₃N₄ ceramics stand out as ideal materials for advanced electronic packaging substrates due to their high mechanical strength, high-temperature resilience, and minimal dielectric constant. Optimizing both the mechanical and thermal conductivity is essential for ensuring their reliable performance. In this study, a systematic investigation into the impact of both oxygen-containing sintering additives (Y₂O₃-MgF₂ and Y₂O₃-MgSiN₂) and oxygen-free sintering additives (YF₃-MgF₂ and YF₃-MgSiN₂) on the microstructure, flexural strength, and thermal conductivity of Si₃N₄ ceramics has been performed. It demonstrates that the Si₃N₄ ceramic sintered with the YF₃-MgSiN₂ additive achieves a remarkable thermal conductivity of 111.63 W·m⁻¹·K⁻¹ and a flexural strength of 774.7 MPa, which is relatively rare among the reported Si₃N₄ ceramics. These exceptional properties are attributed to the use of YF₃-MgSiN₂ additive, which leads to a significant reduction in lattice oxygen content, along with a decrease in the liquid phase formation temperature, thereby promoting grain development. Furthermore, the decomposition of MgSiN₂ at high temperatures plays a key role in purifying the grain boundaries. This study provides a promising approach for developing high-performance Si₃N₄ ceramics with excellent thermal conductivity and mechanical strength.

In response to environmental challenges and primary resource scarcity, sustainable approaches that rely on recycling and reusing waste materials are becoming highly valuable and appealing options in modern society. These strategies have started being applied in biomaterials science, too, leading to the advent of new synergies between apparently distant fields. This review article aims to provide a systematic, up-to-date survey of the existing literature and available commercial products in this emerging area, with a focus on sustainable bioceramics and polymer-based composites for bone tissue engineering applications. The use of natural, inexpensive resources (e.g., waste from fishery and agri-food industries) and, in general, the implementation of green synthesis approaches is considered. Regulatory aspects and barriers for the widespread use of these sustainable products are also comprehensively discussed.

Novel compositionally complex borides, (Hf,Zr,Nb,Ti)B₂ and (Hf,Zr,Nb,Ti)B₂‒LaB₆, were fabricated using spark plasma sintering process. (Hf,Zr,Nb,Ti)B₂‒LaB₆ exhibits a dual-phase microstructure, in which (Hf,Zr,Nb,Ti)B₂ is a primary phase with the hexagonal structure and LaB₆ is a secondary phase with a cubic structure. The mechanical properties of both (Hf,Zr,Nb,Ti)B₂ and (Hf,Zr,Nb,Ti)B₂‒LaB₆ are comparable, with a combination of high hardness and moderate fracture toughness. Thermal diffusivity and conductivity of (Hf,Zr,Nb,Ti)B₂ are much lower than the individual transition metal borides but are significantly increased by the addition of LaB₆. Herein, it is implied that the thermal properties of boride ceramics can be controlled through the appropriate design of principal metal element compositions.

This study compares the effects of ultrafast high-temperature sintering (UHS) and conventional sintering on the microstructural and mechanical properties of 4 mol% yttria-stabilized zirconia, a ceramic widely used in dental restorations for its high strength, biocompatibility, and aesthetic qualities. UHS enabled full densification in just 5 min—a significant reduction compared to the 10-h cycle required for conventional sintering. Both methods yielded similar relative densities (>96%); however, UHS stabilized the tetragonal phase and resulted in a slight reduction in flexural strength. Microstructural analysis revealed coarser surface grains in UHS specimens, indicating distinct grain growth kinetics under rapid heating conditions. Despite the reduction in strength, UHS-sintered samples met the ISO 6872 minimum flexural strength requirement (>300 MPa), confirming their clinical applicability. These findings support UHS as a viable, time-efficient alternative for processing dental zirconia, with potential for high-throughput applications in restorative dentistry.

Waste foundry sand (WFS) is a solid waste by-product generated during the sand casting process in foundries. Promoting resourceful recycling of WFS is of significance for environmental and efficient resource utilization. In this study, WFS was used as the raw material to fabricate ceramic foams using the particle-stabilized foam method. The results showed that the ball-milled fine WFS particles in the slurry were able to adhere to air bubbles, leading to the formation of ceramic foams with closed pores after drying and sintering. The liquid phase generated during the sintering process from melted WFS contributed to the development of dense pore walls. The porosity of the ceramic foams first decreased from 30.93% to 22.83%, and then increased to 40.22% with the rise in slurry pH from 2 to 5. Moreover, the porosity gradually decreased from 49% to 3% as the sintering temperature increased from 1000°C to 1300°C. The variations in the pore structure significantly influenced their properties. The WFS-based ceramic foams were produced with 0.68‒1.32 g/cm³ volume density, 32.4‒210.3 MPa compressive strength, and 0.18‒0.87 W/(m K) thermal conductivity. This study facilitated the reuse of WFS, enhancing cost-effective, efficient production of high-performance ceramic materials for building insulation.

Titanium alloys offer high strength-to-weight ratios and corrosion resistance but lack sufficient wear resistance, especially at elevated temperatures, limiting their use in high-friction environments. To address this, we propose modifying SiC whiskers with Fe₃O₄ (Fe₃O₄/SiCw) to achieve controllable alignment in chemically bonded phosphate ceramic coatings (CBPCs) via magnetic response. This approach successfully constructs an ordered reinforcement structure in CBPC. We investigated the chemical structure of Fe₃O₄/SiCw hybrids and Fe₃O₄/SiCw-reinforced CBPC, along with high-temperature wear tests, to analyze the effects of Fe₃O₄/SiCw content and alignment on wear resistance. Results show that increasing Fe₃O₄/SiCw content significantly reduces both the friction coefficient and wear rate of CBPC at high temperatures. Mf-CBPC5 exhibited the best wear resistance, with wear rates reduced by 19.82% (100°C), 26.14% (250°C), and 53.92% (400°C) compared to CBPC5. The aligned Fe₃O₄/SiCw enhances coating compactness, improves load transfer, and stabilizes friction film formation, significantly boosting CBPC's wear resistance.

This work reports the exploration of high-entropy rare-earth disilicates (HEREDs) with exceptional calcium–magnesium–aluminosilicate (CMAS) corrosion resistance at 1673 K through multicomponent synergistic effects. To be specific, 24 variants of HERED-xRE (RE = Gd, Ho, Er, Tm) samples are successfully fabricated via a pressure-less sintering approach, and their CMAS corrosion resistance at 1673 K is systematically tested. The as-fabricated HERED-60Tm samples are found to possess the best CMAS corrosion resistance with a corrosion depth of approximately 320 ± 12 µm at 1673 K for 48 h. Further studies have attributed such an excellent CMAS corrosion resistance to the multicomponent synergistic effects, resulting in the optimized thermodynamic reactivity and favorable diffusion kinetics in the as-fabricated HERED-60Tm samples. This work provides new insights into the improved CMAS corrosion resistance of HEREDs by the multicomponent regulation, advancing the development of novel thermal /environmental barrier coating materials.

Innovative nanodiamond (ND)–silicon nitride polymer-derived ceramics with different concentrations of nanocarbon phase were developed within the present work and their performance as adsorbent materials for CO₂ was established. The novel preparative approach consists in the synthesis of a polysilsesquiazane in the presence of different concentrations of chemically functionalized NDs, yielding homogeneous ND–polysilsesquiazane composites which were subsequently thermally converted in Argon atmosphere into micro- and mesoporous ND–Si₃N₄ nanocomposites. The ND–Si₃N₄ nanocomposites were carefully investigated by several characterization methods such as vibrational spectroscopy, solid-state magical angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, X-ray diffraction, brunauer-emmett-teller (BET), high-resolution transmission electron microscopy (HRTEM), and CO₂ adsorption, respectively. The incorporation of NDs in silicon nitride matrix enhances the resistance against crystallization of silicon nitride phase, as α-Si₃N₄, at T > 1300°C, while their full graphitization is also shifted to higher temperatures as compared to their raw analogues, demonstrating the synergistic effect of composing phases. The results achieved within the present study allow for designing advanced and well-defined micro- and mesoporous 0D ND-containing silicon nitride composites with tailored structural features suitable for CO₂ capture technology.

Hydrogen-based shaft furnace direct reduction technology is a critical pathway for low-carbon metallurgy. However, there is a scarcity of research on reduction resistance and corrosion mechanisms of Al₂O₃–SiO₂ refractories for hydrogen-based shaft furnaces. This study integrated thermodynamic simulation with reduction testing under conditions mimicking industrial hydrogen-based shaft furnace parameters. The evolutions in mass, mechanical strength, phase composition, and microstructure of four representative Al₂O₃–SiO₂ refractories were systematically analyzed before and after exposure to H₂/CO reducing environments, and their corrosion mechanisms were investigated. The corrosion process involves gas penetration, diffusion, and chemical reactions. SiO₂ and Fe₂O₃ were identified as the primary reactive phases in these refractories. SiO₂ reacts with H₂ to produce gaseous SiO and water vapor, whereas Fe oxides catalyze CO decomposition, leading to carbon deposition. Progressive detachment of deposits and gaseous product escape causes structural damage, resulting in specimen mass loss and strength reduction. Elevated reduction pressure and CO presence in the atmosphere exacerbate refractory corrosion.