High-entropy ultrahigh temperature ceramics (UHTCs) have garnered significant attention for their outstanding designability and performance, yet existing strategies remain largely confined to cationic sublattice engineering, leaving the potential of anionic site manipulation unexplored. Herein, we extend the entropy-stabilization paradigm to the anion sublattice by designing a multianion Hf0.8Zr0.2B0.1C0.5N0.4 solid solution. The resulting Hf0.8Zr0.2B0.1C0.5N0.4–SiC ceramic achieves negative ablation rates (−0.049 and −0.287 μm·s−1) under 2600 °C plasma flame exposure, markedly outperforming Hf0.8Zr0.2C–SiC. This exceptional ablation-resistant performance originates from the synergistic effects enabled by multianion sublattice engineering. The incorporation of B–C–N intrinsically enhances fracture toughness, while in situ precipitation of hexagonal graphite during ablation extrinsically arrests cracks through interfacial shear, preventing catastrophic disintegration. Furthermore, the multianion matrix undergoes a sequential oxidation process, forming an HfZrBCNO interlayer that acts as an oxygen scavenger. Concurrently, h-BN precipitates at grain boundaries, serving as compliant diffusion barriers that impede oxygen ingress into SiC. This dual-layer protection mechanism suppresses the active oxidation of SiC (SiC + O2 → SiO + CO) and promotes the formation of a dense, scouring-resistant HfZrO2–SiO2 composite barrier. By demonstrating simultaneous microstructural toughening and mesoscale oxidation management, this work establishes multianion sublattice engineering as a transformative platform for designing next-generation thermal protection materials beyond the limits of conventional entropy-stabilized ceramics.

The sealing capacity of caprock is critical for preventing CO2 migration and ensuring the safety of geological storage. However, existing research lacks a comprehensive overview of its sealing mechanisms and failure risks. Here, recent findings on caprock sealing mechanisms, its influencing factors, failure risks, and evaluation methods are summarized. The main results include the following: (i) Caprock sealing mechanisms include capillary, hydraulic, hydrocarbon concentration, and hydrate sealing. (ii) Capillary and hydrate sealing block fluid-phase CO2, hydrocarbon concentration sealing prevents diffusive CO2, and hydraulic sealing prevents fluid and water-soluble phases. (iii) The sealing capacity is influenced by the storage site, stratigraphic environment, and caprock properties, with breakthrough pressure ranked as follows: gypsum rock > salt rock > mudstone/shale > limestone > silty mudstone. (iv) Diffusion leakage occurs when the diffusion coefficients is less than 10−12 m2/s, the seepage leakage ranges between 10−8 m2/s and 10−12 m2/s, and the fracture leakage is greater than 10−8 m2/s. (v) Hydro-mechanical (HM) coupling mechanisms, including CO2 diffusion, breakthrough migration, uplift deformation, and fracture flow, are essential for leakage risk simulations. Future research should address sealing mechanisms under complex conditions, define leakage risk thresholds, optimize multiphysical coupling computations, and implement effective engineering solutions to mitigate leakage risk.

High-entropy ultrahigh temperature ceramics (UHTCs) have garnered significant attention for their outstanding designability and performance, yet existing strategies remain largely confined to cationic sublattice engineering, leaving the potential of anionic site manipulation unexplored. Herein, we extend the entropy-stabilization paradigm to the anion sublattice by designing a multianion Hf0.8Zr0.2B0.1C0.5N0.4 solid solution. The resulting Hf0.8Zr0.2B0.1C0.5N0.4u2013SiC ceramic achieves negative ablation rates (u22120.049 and u22120.287 u03BCmu00B7su22121) under 2600 u00B0C plasma flame exposure, markedly outperforming Hf0.8Zr0.2Cu2013SiC. This exceptional ablation-resistant performance originates from the synergistic effects enabled by multianion sublattice engineering. The incorporation of Bu2013Cu2013N intrinsically enhances fracture toughness, while in situ precipitation of hexagonal graphite during ablation extrinsically arrests cracks through interfacial shear, preventing catastrophic disintegration. Furthermore, the multianion matrix undergoes a sequential oxidation process, forming an HfZrBCNO interlayer that acts as an oxygen scavenger. Concurrently, h-BN precipitates at grain boundaries, serving as compliant diffusion barriers that impede oxygen ingress into SiC. This dual-layer protection mechanism suppresses the active oxidation of SiC (SiC + O2 u2192 SiO + CO) and promotes the formation of a dense, scouring-resistant HfZrO2u2013SiO2 composite barrier. By demonstrating simultaneous microstructural toughening and mesoscale oxidation management, this work establishes multianion sublattice engineering as a transformative platform for designing next-generation thermal protection materials beyond the limits of conventional entropy-stabilized ceramics.

Short carbon fiber reinforced ultrahigh temperature ceramic matrix composites (Csf/UHTCMCs) are recognized as leading candidates for thermal structures owing to their precisely tailorable composition and enhanced tunability in structure and properties. Inspired by nature, the Bouligand structure-characterized by a gradual angular rotation between successive layers-exhibits remarkable load-bearing and thermal conductive capacity. In this study, the Bouligand structure was introduced into Csf/ZrB2-SiC by employing direct ink writing technology. The results indicate that the composite with a 30 degrees interlayer Bouligand structure achieves a synergistic improvement in both mechanical performance and thermal diffusion uniformity. Specifically, enhancements of 42% in flexural strength and 35% in fracture toughness were achieved compared to conventional Csf/ZrB2-SiC. Meanwhile, the Z-axis thermal conductivity increased by 24.5%, along with a notable enhancement of in-plane thermal diffusion. These improvements can be attributed to the smaller deflection angles and more frequent unidirectional deflections within the 30 degrees Bouligand structure, which promote more pronounced crack deflection. Furthermore, the small-angle rotational design improves in-plane thermal diffusion uniformity by leveraging the high intrinsic radial thermal conductivity of short carbon fibers. Hence, the bioinspired Bouligand structure design offers a promising strategy for the synergistic optimization of mechanical and thermal properties in Csf/UHTCMCs.

The sandwich structure with ceramic matrix composites (CMCs) skin and carbon form (CF) core is the ideal thermal structural components with excellent thermal protective and lightweight properties in hypersonic vehicles. However, the temperature gradient and mismatch of thermal conductivity between CMC skin and CF core result in the thermal stress in sandwich structures. Therefore, core material CF with matching thermal conductivity have become very important to prevent cracks and debonding of the sandwich structure. In this work, carbon nanotubes (CNTs) reinforced carbon foam composites with different microstructure were fabricated using simple phenolic resin foaming followed by CVI process. The prepared CF display a very low density of 0.075 g/cm3 and a relatively high compressive strength of 1.65 MPa. By controlling the distribution position and content of CNTs the thermal conductivity of core materials CF/CNTs (4.93 W·m− 1·K− 1 which is 13 times higher than that of CF) can be regulated to compatibility with CMCs skin (3.5 6.0 W/m·K). And the thermal conductivity evolution mechanisms of the CF/CNTs from room temperature to 1200 ℃ were revealed. High interfacial thermal resistance by phonon scattering between the CF and CNTs blocks the solid conduction of materials at room temperature. With the increase of the temperature, radiative heat transfer between CF and CNTs becomes more violent and dominates the heat transfer path. The C/CMCs-CMCs sandwich structure was fabricated quickly by the in situ foaming method.

Ultra-high temperature ceramic matrix composites (UHTCMCs) are leading candidates for aerospace thermal protection, wherein fiber selection critically determines their ultimate performance. This work investigates hybrid Cf /ZrC-SiC composites reinforced with polyacrylonitrile-based carbon fibers (PANCF) and mesophase pitch-based carbon fibers (MPCF) at varying ratios. The composite with an MPCF: PANCF ratio of 3:1 achieves balanced thermomechanical performance with a flexural strength of 416 MPa (an 11.53% increase over the pure MPCF composite) and a thermal conductivity of 77.05 W.m(-1).K-1 (a 626.20% increase over the pure PAN composite). Finite element analysis confirms that high thermal conductivity promotes rapid heat dissipation, reducing surface overheating. After ablation testing at 3.3 MW/m(2) for 90 s, PM3 achieves linear and mass ablation rates of 2.332 mu m/s and 0.949 mg/s, respectively, with a surface temperature 182 degrees C lower than that of the pure PAN composite. Enhanced thermal transport promotes a thinner and more uniform oxide layer, and increases viscosity through fine ZrO2 precipitation in the SiO2 glassy phase. This work provides a novel strategy for designing UHTCMCs with co-optimized mechanical and thermal properties.

In this work, YB4-CrSi2 surface-modified Cf/ZrB2-SiC composites were fabricated by a slurry coating method. The cyclic ablation resistance of the composites was studied at 2600 degrees C for 300 s using an air plasma test. The ablation mechanisms of the composites were discussed. The Y3+ can prevent the phase transition of the ZrO2 and increase the structural stability of the oxide layer. But the oxide layer cannot prevent the inward O penetration resulting from the forming of Zr0.9Y0.1O1.95 grains with abundant oxygen vacancy. After the modification of CrSi2, the size of Zr0.9Y0.1O1.95 grains can be reduced to nano scale. The adequate SiO2 glassy phase with the uniform distribution of the Zr0.9Y0.1O1.95 nano grains can prevent the O penetration effectively and reduce the mass recession rate of the composites.

An efficient method for synthesizing sulfonyl fluorides by fluorinating sulfonyl hydrazides with 10 % F2/N2 was developed. This transformation demonstrated a broad substrate scope, yielding a series of sulfonyl fluorides in moderate to good yields. Additionally, a 10 g scale experiment was conducted, demonstrating the practicality of this method.

Ultrahigh temperature and long-term ablation-resistant properties are critical and challenging for the utilization of materials as the thermal components of hypersonic vehicles. In this work, Y2O3 reinforced C-f/HfB2-SiC composites are designed and fabricated, which present superior ablation resistance with a mass recession rate of 2.10 mg/s and linear recession rate of 0.67 mu m/s (with 3 wt% Y2O3 addition) under long term ablation at a heat flux of 5.5 MW/m(2) (up to similar to 2700 degrees C) for 300 s. The long-term ablation mechanisms of the composites are studied and revealed with the help of a detailed microstructure analysis and thermodynamic considerations. It is indicated that Y2O3 reacts with both HfO2 and SiO2, leading to the formation of a stable oxide layer with small HfO2-based grains skeleton dispersed in HfO2-Y2O3-SiO2 glassy phase, subsequently improving the ablation-resistant performance of the composites. This work inspires new strategies for further optimization of ablation resistance of ultra-high temperature ceramic matrix composites.

The corrugated steel-concrete composite (CSCC) arch exhibits high stiffness, excellent ductility, and superior ultimate resistance, making it a promising solution for bridge and tunnel engineering applications. Arch structures in engineering applications are primarily subjected to compression-bending loading. However, research on the compression-bending behavior of CSCC arches remains limited. Furthermore, the lack of a design method for the compression-bending capacity of CSCC arches further hinders their engineering applications. To investigate the behavior of CSCC arches under compression-bending loading, experimental investigations were conducted on two 6 m span CSCC arches subjected to varying loading conditions (mid-span load and quarter-span load), and the failure modes, ultimate resistance, and composite actions were analyzed. The results indicate that under mid-span loading and quarter-span loading, the concrete was crushed due to excessive symmetric and antisymmetric deformations, respectively. Compared with the quarter-span loading condition, the arch subjected to mid-span loading exhibited a higher ultimate resistance but reduced stiffness. A finite element (FE) model of the CSCC arch was established and verified, and then applied to investigate the effects of material strength, section geometry, and corrugation size on its behavior under compression-bending loading. Finally, a design method was proposed to predict the compression-bending capacity of the CSCC arch.

TaC and HfC can theoretically dissolve each other indefinitely to form binary TaxHf1-xC (0 < x < 1) solid solution ceramics. TaxHf1-xC ceramics are ideal candidates for thermal protection materials for hypersonic vehicles. Ablation-resistant performance of ceramics is critical for the applications under harsh environments. In this work, highly dense TaxHf1-xC-SiC ceramics were fabricated at 1700 degrees C by reactive hot-pressing. Ablation behavior and mechanisms of the ceramics were investigated via air plasma testing at a heat flux of 6 MW/m(2), with the focus on the effect of Ta: Hf ratio. It is revealed that the Ta content has a significant influence on the ablation surface temperature and the ablation-resistant properties. The Ta0.2Hf0.8C-SiC ceramic has the highest ablation surface temperature of 2968 degrees C but presenting the lowest linear ablation rate of 0.15 mu m s(-1). As the Ta content increases, the ablation surface temperature of the ceramics tends to decrease, with the lowest temperature of 2447 degrees C for Ta0.8Hf0.2C-SiC. The Ta0.6Hf0.4C-SiC ceramic shows the worst ablation resistance, with the highest linear ablation rate of 8.1 mu m s(-1). Detailed ablation-resistant mechanisms of the TaxHf1-xC-SiC ceramics were revealed based on systematic thermodynamic and microstructure analysis. This work lays the foundation for the composition design of TaxHf1-xC-based ceramics and composites.

It is a common phenomenon for droplets to impinge on wall in corrugated plate dryer. In this paper, the numerical simulation of double droplets impinging on the inclined wall simultaneously is carried out by CLSVOF method(Coupled Level-Set and VOF Model). The morphology, pressure, daughter droplets distribution and central sheet width of double droplets impinging on the inclined wall along the longitudinal and crosswise directions are analyzed. It is found that the pressure at the central sheet position decreases with the increase of inclined angle in the early stage, and increases with the increasing of inclined angle in the later stage in crosswise directions, which is because the pressure change in the early stage is mainly caused by the velocity component of perpendicular to the wall direction, while the pressure change in the later stage is mainly caused by velocity component of the droplets along the wall direction. However, the impingement along the longitudinal direction is easier to generate splash phenomenon than the impingement along the crosswise direction, and the quantity of daughter droplets is more. The width of central sheet decreases with the increasing angle when droplets impinge along the longitudinal direction,but increases with the increasing angle when droplets impinge along the crosswise direction.

In the corrugated plate dryer, there are a lot of phenomena of multi-droplets impacting on the liquid film. Therefore, the analysis of droplets successively impacting on liquid film has important engineering significance. In this paper, the CLSVOF method is used to simulate the successive impact of two droplets on the liquid film. By analyzing the velocity and pressure distribution of the liquid film and the motion state of the residual film, the influence of the droplets spacing, the initial liquid film thickness and the impact velocity on the impact outcomes is obtained, and the influence mechanism is analyzed. The simulation results show that the inner crown is easy to splash with the increase of the droplets spacing; with the increase of impact velocity, the inner crown is easy to splash;with the increase of the initial liquid film thickness, the inner crown is not easy to splash.

Structure and stealth integrated materials that simultaneously deliver mechanical loading and broadband electromagnetic wave (EMW) absorption performance are critical for next generation stealth aircraft. Although conventional carbon fiber reinforced ceramic matrix composites (Cf/CMCs) exhibit outstanding load-bearing capacity, their inherent EMW reflection characteristics often fail to meet stealth requirements. This work proposes a multiscale design strategy synergizing microscopic defect engineering with macroscopic gradient permittivity modulation. Accordingly, (SiO2-C)f/(CrZrHfNbTa)C-Si3N4-SiBCN composite featuring self-adaptive impedance matching and multi-mechanism EMW absorption were successfully constructed. The material demonstrates acceptable load-bearing capacity (101 +/- 5 MPa) while achieving a remarkably high effective absorption bandwidth (EAB) per unit thickness (2.68 GHz mm-1). More importantly, radar cross section (RCS) simulations reveal that the sample achieves a remarkable RCS reduction of 35.52 dB m2. This surpasses most reported materials system, demonstrating high practical application potential. Density functional theory calculations reveals that defect engineering (lattice distortion and point defects) in the sample constructs new polarization centers at the microscopic level, which significantly enhances polarization relaxation loss for improved EMW absorption. On the other hand, macroscopic structural design (SiO2f-Cf-SiO2f) significantly optimizes the impedance matching, which effectively broadens EAB. The multiscale design strategy overcomes the inherent conflict between strong EMW reflection and attenuation in carbon fibers, which provides a novel material solution for stealth aircraft.

Air plasma ablation behavior of Cf /(Ti0.2 Zr0.2 Hf0.2 Nb0.2 Ta0.2 )C-SiC composite was studied systematically with the surface temperature above 20 0 0 degrees C at the ablation center. It presents a linear recession rate of 0.15 mu m/s and a mass recession rate of 2.05 mg/s after ablation at 4 MW/m2 (20 0 0 degrees C) for 30 0 s. Associated with the temperature gradient of the ablation surface, the oxidation products at different locations mainly consist of (TiZrHfNbTa)Ox , (Zrx Hf1-x )6 (Nby Ta1-y )2 O17 , Ti(Nbx Ta1-x )2 O7 , (Hfx Zr1-x )SiO4 , and SiO2 . Due to the synergistic effect of the multi-component oxides, oxidation products form a protective structure composed of high melting point oxide skeleton filled with relatively low melting point phases. It retards oxygen inward diffusion and prevents the composite fragmentation caused by plasma mechanical scouring. It is believed that the results would be helpful for further improving the ablation resistance by component design of high entropy ceramics and their composites. (c) 2024 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

In this work, a novel multi-anion ultra-high temperature ceramic (UHTCs) powder-Hf0.8Zr0.2B0.1C0.5N0.4, was designed and synthesized by carbothermal and borothermal reduction above 1400 degrees C using B4C, carbon black, and N2 as boron, carbon, and nitrogen sources, respectively. The as-synthesized Hf0.8Zr0.2B0.1C0.5N0.4 powder has a rock-salt crystal structure and high compositional homogeneity, with lattice constant of 4.602 & Aring;. It has an average particle size of similar to 0.13 mu m and low oxygen content of similar to 0.43 wt%. This work not only expands the category of UHTCs but also opens a new insight to develop and design UHTCs with multi-anion and cation structures for performance optimization.

The ultra-lightweight and multifunction integrated thermal protection materials are critical for the development of hypersonic vehicles. Although various materials have been developed as potential thermal protection materials, most of them generally present a singular function. It is still challenging to meet the multifunctional requirements of ultra-lightweight, thermal insulation, electromagnetic interference (EMI) shielding, and high-temperature ablation resistance. Herein, a gradient Cf /(CrZrHfNbTa)C-SiC composite is designed and fabricated based on the bionic strategy of capillary adsorption and transport. The developed gradient Cf /(CrZrHfNbTa)C-SiC composite is as light as 0.74 g/cm3 , which shows excellent ablation resistance (-3.88 mu m/s at 20 0 0 degrees C). It also presents competitive thermal insulation performance with a back temperature below 152 degrees C while enduring 1300 degrees C on the front side. The thermal conductivity of the gradient composite is 0.202 W m-1 K-1 . Furthermore, the gradient Cf /(CrZrHfNbTa)C-SiC composite offers remarkable EMI shielding performance with mean total EMI shielding efficiency (SET ) larger than 45 dB in an ultra-wide frequency range of 0-100 GHz. The excellent multifunctional performance with ultra-lightweight makes the gradient Cf /(CrZrHfNbTa)C-SiC composite ideal thermal protection materials for hypersonic vehicles. This work provides a flexible strategy for constructing gradient composites for multifunctional applications. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.