Transient plasma ablation and molten aluminum contamination are major degradation modes of resin-based insulating supports in electromagnetic rail launchers. In this work, Al2O3/polyimide (PI) composite coatings with different thermoplastic/thermosetting PI ratios (TPI/TSPI = 10:0, 7:3, 5:5, and 3:7) were deposited on glass fiber reinforced epoxy resin substrates by wide-velocity-range high-energy plasma spraying. The TPI/TSPI ratio affected the powder thermal response, splat spreading, coating defects, and residual layer stability after ablation. PI73 showed a balanced coating structure and exhibited the lowest mass ablation rate of 0.024 g·s−1 after 150 plasma ablation cycles, corresponding to a 78.9% reduction compared with the resin substrate, while retaining a flexural strength of 232.61 MPa. After molten aluminum erosion, the Al2O3/PI coating maintained volume resistivities above 1010 Ω·cm. Ablation and erosion results indicated that the retained Al2O3-rich framework, PI-derived carbonaceous products, and lamellar coating structure contributed to residual layer integrity and molten aluminum penetration resistance. The proposed regulation strategy for the ratio of thermoplastic to thermosetting resins offers a novel design route for protective coatings against synergistic erosion by high temperature and molten aluminum.

Multicomponent doping is an effective strategy for regulating the properties of rare-earth zirconate thermal barrier coating (TBC) materials. In this study, three types of multicomponent co-doped A2B2O7 ceramics-(La1/ 3Nd1/3Gd1/3)2(Zr1/2Hf1/2)2O7,(La1/3Nd1/3Gd1/3)2(Zr1/3Hf1/3Ti1/3)2O7, and(La1/3Nd1/3Yb1/3)2(Zr1/3Hf1/3Ti1/ 3)2O7-were synthesized via the solid-state reaction method by co-doping cations with distinct valences at the A and B sites. Their phase stabilities and thermophysical and mechanical performances were comprehensively investigated. These materials exist as a single pyrochlore phase and exhibit remarkable phase stability at high temperatures. Compared with La2Zr2O7, the synthesized ceramics exhibit low thermal conductivities (1.17-1.51 W m-1 K-1 at 25 degrees C), improved thermal expansion coefficients (9.6-10.3 x 10-6 K-1 at 1000 degrees C), coupled with relatively moderate elastic moduli (160.53-187.62 GPa) and comparable fracture toughnesses (1.32-1.59 MPa m1/2). The reduction in thermal conductivity is achieved without compromising stiffness. The addition of TiO2 accelerates the diffusion process and enlarges the grain size; however, it can also weaken the bond strength, thereby increasing the thermal expansion coefficients. This study provides a significant theoretical foundation for the advancement of high-performance TBC materials.

Transient thermo-erosion induced by thermal plasma and molten aluminum armature droplets during electromagnetic rail launcher (EMRL) operation is a major cause of performance degradation in insulating supports. Surface coatings provide an effective route for improving their service reliability. In this work, Al2O3/PI composite coatings were deposited on glass-fiber-reinforced epoxy resin (GFRP) substrates by wide-velocity range high-energy plasma spraying (WPS). By varying the ratio of thermoplastic polyimide (TPI) to thermosetting polyimide (TSPI) (10:0, 7:3, 5:5, and 3:7), the effects of dual-phase PI composition on coating microstructure, mechanical properties, ablation resistance, and insulation performance were systematically investigated. The results showed that PI73 exhibited the lowest mass ablation rate after 150 plasma ablation cycles, while maintaining a high flexural strength of 228.61 MPa. After molten aluminum erosion, the Al2O3/PI composite coatings still maintained markedly higher volume resistivity than the substrate. This behavior is attributed to the synergistic protection of the Al2O3/PI coating, where the ceramic phase promotes heat dissipation and residual-layer stability, while the polymer phase contributes to penetration resistance and structural integrity. The present study demonstrates that an appropriate thermoplastic/thermosetting dual-phase PI design is effective for simultaneously improving the ablation resistance and insulation performance of Al2O3/PI composite coatings, and provides a new design route for resin-based insulating materials operating under extreme thermo-erosive conditions.

Achieving low thermal conductivity remains a key objective in the development of advanced thermal insulating materials. Using a dual-site co-doping strategy, a novel single-phase pyrochlore ceramic, (Gd0.5Yb0.5)(2)(Zr0.5Ti0.5)(2)O-7, is designed and synthesized by a solid-state reaction method. The material exhibits excellent phase stability at high temperatures. Its fracture toughness and thermal expansion coefficient are 2.13 +/- 0.11 MPa m(1/2) and 10.87 x 10(-6) K-1, respectively, both higher than those of the single-component counterparts Gd2Zr2O7, Gd2Ti2O7, or Yb2Ti2O7. The co-doped composition also exhibits a low thermal conductivity of 1.30 W m(-1) K-1, along with characteristic temperature-independent behavior typical of amorphous-like thermal transport. More importantly, the decrease in thermal conductivity is achieved without compromising rigidity, highlighting its tremendous potential for high-performance thermal barrier coating applications.

Rare-earth monosilicates (REMs) exhibit excellent resistance to calcium-magnesium-alumino-silicate (CMAS) corrosion, but the vast compositional space, particularly for non-equimolar ratios, poses significant challenges for rapid development and mechanistic understanding. In this work, a reverse design strategy was employed to tailor non-equimolar REMs, coupled with a multiscale investigation framework. Density functional theory trained neuroevolution potential molecular dynamics simulations, revealed the atomic-scale CMAS corrosion mechanism: initial interfacial contact, interdiffusion with bridging oxygen formation and substitution channel migration, and final apatite phase precipitation. Lattice distortion in the REMs mainly from RE cation sites and spatial reorientation of [SiO4] tetrahedra. Data-driven models for residual melt viscosity and phase evolution demonstrated strong cross-scale consistency, identifying Sc-rich compositions as exhibiting superior corrosion resistance during the initial stages of CMAS attack at 1400 degrees C. This combined data-driven, simulation, and experimental workflow offers a robust pathway for building multiscale frameworks to alleviate CMAS degradation in environmental barrier coatings.

Iron-based amorphous coatings (Fe-AMCs) are promising candidates for corrosion protection. However, it remains challenging to achieve a dense microstructure with few defects while maintaining a high amorphous phase content. In this study, Fe-Cr-Si-Mo-Mn-Ni-W amorphous coatings were deposited onto 316 L stainless steel using the wide-velocity-range plasma spraying (WPS) method, with five parameter combinations varying in argon flow rate and spray current. The phase composition, amorphous phase content, microstructure, porosity, bond strength, microhardness, and electrochemical corrosion behavior in a 3.5 wt% NaCl solution were systematically investigated. The results showed that the feedstock powders were nearly fully amorphous (98%), whereas the as-sprayed coatings retained 90% ∼ 96% of the amorphous phase, indicating that partial crystallization occurred during deposition. Within this high amorphous retention range, the coating with the highest amorphous phase content did not exhibit the highest corrosion resistance. In contrast, the coating with the lowest porosity (1.4%) exhibited the highest charge transfer resistance (1863 Ω·cm2) and the lowest corrosion current density (21.25 μA·cm−2). These results revealed that, within the examined WPS process window where the amorphous phase content of the coatings ranged from 90% to 96%, differences in corrosion resistance were governed primarily by coating compactness and defect connectivity, rather than by relatively minor variations in the amorphous phase content itself.

In this study, nanocrystalline Dy2O3, Gd2O3, Sc2O3, and Y2O3 co-stabilized ZrO2 (DyGdScYSZ) ceramic powders were synthesized by a sol-gel route followed by calcination. The individual and combined effects of calcination temperature and Dy doping content on the microstructural and grain growth of the resulting powders were systematically investigated. After spray granulation, the powders were sintered using two parallel routes: Conventional sintering (CS) and Rapid sintering (RS). The breakage resistance of the sintered agglomerated powders was quantitatively evaluated through compression testing using a universal testing machine. The results demonstrate a key innovation: despite only 10 minutes of exposure 1200 °C, the RS process yields grain sizes and powder strengths comparable to those obtained after 2 hours of CS. Remarkably, within this ultra-short timeframe (10 min), nanocrystalline ZrO2 exhibits an exceptionally high dense-layer growth rate and diffusion flux, enabling rapid completion of powder densification and grain growth.

Yttria-stabilized zirconia (YSZ)-based abradable sealing coatings (ASCs) have attracted increasing attention in aero-engine sealing systems. However, their wear resistance at high temperatures remains a critical concern. In this work, two coatings with different unmelted nanoparticle contents (UNCs) were prepared by supersonic atmospheric plasma spraying (SAPS), and the influence of UNC on the high-temperature tribological performance of YSZ ASCs was systematically investigated. The microstructure, phase composition, and wear behavior of coatings were characterized using scanning electron microscopy, X-ray diffraction, and high-temperature tribological tests, respectively. The results showed that at a temperature of 1000 °C, changing the UNC significantly altered the friction coefficient and wear rate of the ASCs. For both coatings, wear behavior is primarily governed by abrasive wear, accompanied by extensive adhesion of wear debris. At elevated temperature, the unmelted nanoparticles act as weak regions within the coating. Under friction-induced shear stresses, they preferentially fragment and detach, which improves the abradability. These findings provide insights into the structural design of high-temperature ceramic-based ASCs.

Surface coking under high temperature degrades the performance and longevity of engine components. Understanding its mechanism is essential for developing effective mitigation strategies. This study integrates density functional theory (DFT), ab initio molecular dynamics (AIMD), and targeted experimental characterizations to uncover the coking mechanism on stainless steel and explain the anti-coking behavior of an ALD-fabricated TiO2 coating. Simulations reveal that Fe/Ni sites on bare steel catalyze the initial cracking of long-chain alkanes (n-decane) into reactive species, which strongly chemisorb through pronounced hybridization between C-p and metal-d orbitals. Conversely, a stable TiO2 coating alters the interfacial chemistry: lowering the adsorption energy of coke precursors by >40% and suppressing accumulation. Crucially, AIMD simulations reveal a surface-oxygen-mediated carbon-removal pathway, in which adsorbed carbon reacts with surface lattice oxygen and desorbs as CO at 700-900 K, underpinning the active carbon desorption behavior of the TiO2 coating. TPSR measurements confirm this mechanism by showing distinct CO desorption peaks between 379 and 800 degrees C. Furthermore, combustion tests demonstrate that the ALD-fabricated TiO2 coating reduces carbon deposition by similar to 75%. Overall, this work providing a theoretical foundation for the rational design of advanced anti-coking coatings.

Low-density rare-earth titanates (RE2Ti2O7) are important candidate materials for thermal barrier coatings (TBCs). Three novel high-entropy titanates, namely(Y0.2Ho0.2Er0.2Tm0.2Yb0.2)2Ti2O7, (Y0.2Eu0.2Gd0.2Ho0.2Yb0.2)2Ti2O7, and(Y0.2Sm0.2Eu0.2Ho0.2Yb0.2)2Ti2O7, are prepared to tailor the thermophysical property of RE2Ti2O7. All samples possess a uniform pyrochlore structure and demonstrate favorable high-temperature phase stability. Compared to Y2Ti2O7, the high-entropy ceramic(Y0.2Sm0.2Eu0.2Ho0.2Yb0.2)2Ti2O7 shows improvements in multiple properties, such as a higher coefficient of thermal expansion (10.94 & times;10-6 K-1 at 1100 degrees C), as well as an amorphous-like thermal conductivity ranging from 1.89 to 2.06 W & sdot;m-1 & sdot;K-1. In addition, the thermal conductivity of (Y0.2Sm0.2Eu0.2Ho0.2Yb0.2)2Ti2O7 is approximately 30% lower than that of Y2Ti2O7 at room temperature. Size disorder acts as a significant factor contributing to the reduction in thermal conductivity of high-entropy titanates, and the decrease in thermal conductivity is accomplished without sacrificing rigidity. The collaborative improvements in both thermal conductivity and thermal expansion coefficient suggest that(Y0.2Sm0.2Eu0.2Ho0.2Yb0.2)2Ti2O7 is a promising candidate for further evaluation in TBC applications.

As promising advanced materials, high-entropy ceramics have demonstrated exceptional mechanical-friction properties that surpass conventional ceramics, but their service characteristics under extreme working conditions still need to be investigated. This study investigated the synthesis of SiCw@Ni core-shell powders with controlled Ni content via heterogeneous precipitation-thermal reduction and their application in reinforcing (Hf, Nb,Ta,Ti,Zr)N high-entropy ceramics fabricated by spark plasma sintering. The optimized SiCw@1.0Ni composition enabled superior sintering behavior through enhanced current conduction, yielding a dense microstructure (98.79 % relative density) with a hardness of 16.91 GPa. Meanwhile, the SiCw@1.4Ni reinforcement demonstrated exceptional mechanical performance, achieving flexural strength of 580.36 MPa and fracture toughness of 8.04 MPa & sdot;m1/2, attributed to the synergistic toughening effects of the core-shell structure and secondary phases Ni/Ni2Si. Under dry-friction conditions (20 N, 200 r/min), the SiCw@1.0Ni composite exhibited the lowest friction coefficient and wear rate, with wear mechanism transition from severe abrasive wear to mild adhesive wear. Enhanced mechanical properties, improved densification, and reduced friction coefficient effectively mitigated surface spalling, preventing severe localized damage to contacting interfaces of the friction pair (ball-disc), and ultimately enhancing the tribological performance of (Hf,Nb,Ta,Ti,Zr)N high-entropy ceramics. We expect our research to provide a practical pathway for breakthroughs in advanced wear-resistant materials.

Silicon carbide whisker (SiCw) toughening (Hf0.2Nb0.2Ta0.2Ti0.2Zr0.2)N (HENs) high entropy nitride ceramic cutting tool materials were fabricated by spark plasma sintering. A face-centered cubic (FCC) structure of the single-phase solid solution (Hf0.2Nb0.2Ta0.2Ti0.2Zr0.2)N was formed after sintering. SiCw remained the whisker morphology and exited the intragranular and intergranular mixed microstructure in the matrix. Under the optimization of sintering parameters, the fracture toughness of HENs cutting tool material reached 7.63 +/- 0.14 MPa m1/2, increased by 18.29 % compared with that of (Hf0.2Nb0.2Ta0.2Ti0.2Zr0.2)N (HEN) ceramic cutting tool materials. In the process of crack propagation, SiCw exhibited active toughening characteristics such as whisker tensile fracture and whisker pulling out, indicating that SiCw with high strength and high hardness effectively prevented the crack propagation, absorbed and reduced the crack propagation energy, and improved the fracture toughness of high-entropy nitride ceramic tool materials. The dry cutting test was carried out to study the effect of SiCw on the cutting performance of quenched 45 steel with high entropy nitride ceramic cutting tools. The results showed that the major wear mechanism of HENs was adhesive wear. The addition of SiCw improved the wear resistance of HENs tools, which resulted in a larger actual working rake angle than that of HEN tools and reduced the cutting force, especially the axial force and the main cutting force reduced by 24.60 % and 18.38 %, respectively. So, HENs tools obtained a longer tool life than HEN tools. In addition, the surface roughness was also improved when using HENs cutting tools, the average Ra reached 0.78 +/- 0.08 mu m within a long cutting distance (800-4800 m).

A method to achieve rapid, low-temperature, traceless bonding of ultrafine-grained carbon nanotubes reinforced aluminum matrix composites (CNTs/Al) is introduced in this paper, providing a new approach for the preparation of large-scale powder ingots for aerospace components. Under the conditions of a temperature of 450 degrees C and 40 % compressive deformation, a seamless joint with bonding strength of up to 395 MPa was rapidly achieved by applying an electric field of 100 A/cm2 for 15 min. Heating and applied pressure facilitate void closure and oxide layer fracture at the thermo-compression bonding interface. Electromigration and thermodiffusion accelerate mass transfer across the bonding interface, thereby mitigating joint softening under prolonged exposure to high temperatures. Additionally, the numerous grain boundaries and phase boundaries within the ultrafine-grained CNTs/Al serve as channels for short-circuit atomic diffusion. Synergistic multi-physics of thermal, mechanical, and electric fields achieves the bonding interface healing of CNTs/Al joints.

To improve the thermophysical performance of hafnate ceramics, we designed and synthesized two innovative high-entropy rare-earth hafnate ceramics, namely (La0.2Nd0.2Sm0.2Eu0.2Gd0.2)2Hf2O7 and (La0.2Nd0.2-Sm0.2Gd0.2Yb0.2)2Hf2O7. The factors influencing their thermophysical properties were illustrated. Both ceramics exhibited a pure pyrochlore structure and displayed a favorable long-term phase stability at high temperature. Compared with the single-component La2Hf2O7, the high-entropy (La0.2Nd0.2Sm0.2Gd0.2Yb0.2)2Hf2O7 material exhibited superior mechanical properties, including enhanced hardness (11.77 f 0.33 GPa) and fracture toughness (2.23 f 0.12 MPa center dot m1/2) values, in addition to a high thermal expansion coefficient (11.1 x 10-6 K-1 at 1100 degrees C) and a low thermal conductivity (1.31 W center dot m-1 center dot K-1 at room temperature). The significantly higher thermal expansion coefficient of this ceramic is primarily attributed to the reduced electronegativity difference between its cations and anions, as well as its lower Debye temperature. Furthermore, the large mass and radius differences among the doped cations serve as key phonon scattering sources, effectively lowering the thermal conductivity without compromising the structural stiffness of the material. This work clarifies the pivotal role of elemental diversity and ionic size mismatch in synergistically modulating the thermophysical properties of hafnates, offering a novel material design paradigm for advanced thermal barrier coatings.

With the aim of revealing the failure process of the thermal barrier coatings (TBCs) during the thermal cycling, a finite element model that incorporated the sintering of ceramic top coat and growth of thermally grown oxides was developed to explore the dynamic propagation behavior of cracks in this study. The results suggested that the propagation of cracks showed a stepwise pattern, in which the cracks rapidly propagated within a very short time once the stress intensity factor reached the fracture toughness of coating. When the coating porosity increased to 15

Long-lasting and high-reliability thermal barrier coatings (TBCs) are critical for next-generation aeroengine applications. In this study, a fiber-toughened coating with a columnar-like structure was fabricated using supersonic suspension plasma spraying (SSPS). Among the various spraying parameters, the suspension injection position and spraying distance were found to significantly affect the porosity and the density of vertical cracks. The incorporation of fibers resulted in a notable reduction in porosity, from 17 % to 5 %, while also enhancing fracture toughness. Thermal shock tests at 1100 degrees C showed that the ZrO2 fiber-reinforced coating with vertical cracks showed a 50 % performance improvement over YSZ coatings, primarily due to a threefold increase in fracture toughness, which is attributed to the fiber pull-out and bridging mechanisms. The controllable vertical crack structure in the proposed coating offers a promising approach to enhancing TBCs performance and longevity.

Hydrogels present significant potential in flexible materials designed for electromagnetic interference (EMI) shielding, attributed to their soft, stretchable mechanical properties and water-rich porous structures. Unfortunately, EMI shielding hydrogels commonly suffer from low mechanical properties, deficient fracture energy, and low strength, which limit the serviceability of these materials in complex mechanical environments. In this study, the double network strategy is successfully utilized along with the Hofmeister effect to create MXene/PAA (polyacrylic acid)-CS (chitosan) hydrogels and further strengthen and toughen the gel with (NH4)2SO4 solution. The gel exhibits enhanced functionalities such as outstanding stretchability, excellent strain sensitivity (11.66), and super fracture energy (>= 9 kJ m-2). Notably, it demonstrates outstanding shielding effectiveness of 73.8 dB in the terahertz (THz) range, and the shielding properties can be effectively tuned by varying the MXene content, the (NH4)2SO4 concentration, and the thickness of the hydrogel. Additionally, the gel shows robust and superior shielding effectiveness after repeated stretching and long-term dehydration. The MXene/PAA-CS double-network (DN) hydrogels would be an excellent candidate for EMI shielding materials in advanced flexible electronic equipment and soft robots.

It is well known that the traditional Y2O3 stabilized ZrO2 thermal barrier coatings (TBCs) are vulnerable to calcium-magnesium-alumina-silicate (CMAS) attack. With the aim of improving the CMAS corrosion resistance of TBCs, a series of Gd-doping Sc2O3-Y2O3 co-stabilized ZrO2 (GdScYSZ) materials were tailored and prepared in this study. The results suggested that only when the doping amount of Gd3+ reached the threshold of apatite phase formation, the excellent CMAS corrosion resistance of TBCs can be achieved. Therefore, the 20GdScYSZ material had outstanding CMAS corrosion resistance, in which a dense interwoven protective layer that consisted of acicular apatite grains and c-ZrO2 grains was formed to resist the corrosion and prevent the penetration of CMAS. In addition, the wettability of the reaction interface was investigated by first-principles calculation. Our work provides a valuable approach for designing TBC materials with remarkable CMAS corrosion resistance.

High-infrared-radiation materials play a crucial role in thermal protection and industrial energy conservation. A series of Cu-doped SrZrO3 high infrared radiation perovskite ceramic were prepared. The effects of Cu ion doping on infrared radiation and thermophysical properties were investigated through both experimental and theoretical approaches. The results indicate that doping with Cu ions can enhance the infrared emissivity of SrZrO3. Furthermore, the introduction of oxygen vacancies and the expansion of lattice volume help alleviate the increase in thermal conductivity associated with electronic thermal conduction. The synthesized SrZr 0.75 Cu 0.25 O 3-delta bulk ceramic demonstrates an emissivity exceeding 0.98 in the 1-22 mu m range at 600 degrees C and greater than 0.5 at 1200 degrees C. Additionally, it has a thermal conductivity of less than 1.8 W center dot m-1 center dot K- 1 at 1200 degrees C. The ceramic also exhibits a temperature isolation value greater than 40 degrees C center dot mm- 1 at 1200 degrees C, indicating an improvement of over 55 % compared to SrZrO3.