International Journal of Applied Ceramic Technology最新文献

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.

Exploiting high-entropy rare-earth monosilicates (HEREMs) with simultaneously improved corrosion resistance and thermophysical properties is vital for their use as next-generation environmental barrier coating materials. Herein, a new dual-phase strategy has been developed to regulate the comprehensive properties of HEREMs. Specifically, by adding 20% Lu₂Si₂O₇ (LuD) into (Ho_0.1Er_0.1Yb_0.4Lu_0.4)₂SiO₅ (HEREM-0.1), novel (Ho_0.1Er_0.1Yb_0.4Lu_0.4)₂SiO₅/Lu₂Si₂O₇ (HEREM-0.1/LuD) dual-phase rare-earth silicates have been successfully fabricated to exhibit a synergistic enhancement in both thermophysical properties and calcium–magnesium–aluminosilicate (CMAS) corrosion resistance, including excellent high-temperature stability without phase transformation up to 1973 K, well-matched coefficients of thermal expansion (3.5–5.7 × 10⁻⁶ K⁻¹) with SiC_f/SiC composites (4.0–5.5 × 10⁻⁶ K⁻¹) across 473–1573 K, extremely low thermal conductivity of 0.8–1.4 W m⁻¹ K⁻¹ from room temperature to 1273 K, and further enhanced CMAS corrosion resistance at 1673 K for 60 h (ultralow corrosion depth of 47 µm). Such superior properties can be attributed to the introduction of the dual-phase structure and the enhanced stability of the formed apatite structure. Our work provides an alternative way to developing HEREMs with outstanding comprehensive properties.

In the present work, a single-source precursor for the production of ZrC was successfully synthesized via a straightforward one-pot strategy using zirconium n-propoxide [Zr(OPr)₄], acetylacetone (Acac), and 1,4-dihydroxybenzene (DHB) as raw materials, with Acac acting as a ligand and DHB as a bridging unit. By adjusting the amount of benzene rings from DHB in the precursor, the free carbon content in the resulting ceramic is precisely controlled. Besides, DHB effects the ceramic yield of the precursor as well as the phase composition and grain size of the resulting ZrC ceramic. The single-source precursor first transforms into ZrO₂ at 600°C and fully converts into ZrC@C nanoceramic with a core–shell structure at 1400°C. The synthetic route is straightforward, the single-source precursor exhibits excellent solubility and air stability, and the ceramic yield at 1400°C reaches up to 45.7%. These advantages make the precursor promising for ceramic matrix composites fabrication via the polymer infiltration and pyrolysis method.

The effects of the oxidation on the micro/nanohardness, density, and microstructure of the silicon nitride–carbon nanotube (Si₃N₄–CNT) composite were investigated. α-Si₃N₄ starting powder was oxidized at a temperature of 1000°C for 10 and 20 h and was used to produce composite samples made via hot isostatic pressing (HIP). Density measurements revealed that the 20-h oxidized α-Si₃N₄-based composite had higher apparent density than the unoxidized and 10-h oxidized ones. The micro/nanohardness results proved that this improvement in the density induces changes in the mechanical properties. After the oxidation process and sintering, the microhardness of the composite remained unchanged at 6.525 and 6.49 GPa for the unoxidized and 10-h oxidized samples, respectively. However, the microhardness was significantly improved, reaching 8.28 GPa for the 20-h oxidized samples. Similarly, the best nanohardness results were obtained in the 20-h oxidized samples, significantly surpassing those of the unoxidized and 10-h oxidized samples. However, some of the scanning electron microscopy images indicate that the CNTs do not disperse or distribute evenly, explaining the large scatter in the nanohardness results. These findings suggest that the 20-h oxidation process significantly enhanced the micro- and nanohardness and density of the Si₃N₄–CNT composite, potentially improving its overall mechanical performance.

In this study, effects of interface contact, adhesion, and reaction behavior between clogging and molten steel under different electric field conditions are studied using the most common aluminum-killed steel clogging as research object. Results show that wettability between Al₂O₃ and molten steel is poor. However, formation of solidified steel and rough surface structure in aluminum-killed steel clogging significantly influence wettability, which enhances formation and growth of clogging. Meanwhile, interfacial contact, wetting, and reaction behavior are controlled by electric field. Positive electric field enhances interfacial contact, reaction, and wettability, which exacerbate formation and growth of clogging on submerged entry nozzle (SEN). Conversely, negative electric field suppresses clogging growth, preserving SEN structure and ensuring stable continuous casting operations.

The primary aim of this study was to evaluate the antibacterial efficacy of the synthesized zinc oxide (ZnO) nanoparticles via solution combustion synthesis, utilizing an aqueous extract of Moringa oleifera. A preliminary biocompatibility assessment on human sperm was also performed to explore potential cytotoxic effects. The inclusion of ammonium nitrate as an additional oxidizing agent significantly influenced the physicochemical properties of the resulting nanoparticles. The particles exhibited average sizes around 10 nm and an increased specific surface area favorable for applications in catalysis, sensors, and electronic devices. Microscopy techniques confirmed the formation of polycrystalline ZnO nanoparticles with irregular and agglomerated morphologies. Antibacterial assays demonstrated strong inhibitory activity against Staphylococcus aureus, indicating potential for biomedical and environmental applications. Additionally, ZnO showed strong activity against S. aureus, with enhanced crystallinity and surface area. Preliminary sperm tests showed low toxicity. These findings support eco-friendly ZnO synthesis for biomedical use.