With the upgrading of information security, target stealth and electromagnetic protection, the urgent development of highly efficient wave-absorbing materials is imperative. This paper briefly describes the working principle of wave-absorbing materials, and comprehends the research progress of coated and structural wave-absorbing materials, and finally focuses on the development of fiber hybrid wave-absorbing composites: the fiber arrangement, component regulation and interface design can synergistically enhance the electromagnetic and mechanical properties. Through multi-fiber synergistic design and multi-scale structural optimization, fiber hybrid wave-absorbing composites can realize the coupling optimization of impedance matching and loss mechanism, and have both broadband absorption and mechanical loading characteristics, which promote the development of wave-absorbing materials in the direction of structural and functional integration. Finally, the technological breakthrough of expanding the wave-absorbing frequency band through multi-fiber blending system is summarized, and the future development of a new generation of dual-use wave-absorbing materials with broadband absorption, lightweight and high-strength characteristics around the deepening of the fiber blending mechanism, multi-scale structural design, improvement of the environmental adaptability, multi-functional integration, synergistic control of the fiber orientation and angle of incidence, and the development of high-temperature ceramic-based wave-absorbing materials are prospected.

With the rapid advancement of modern electronic and communication technologies, there is an increasing demand for high-performance electromagnetic wave（EMW）absorbing materials. Materials that combine lightweight properties, high-temperature resistance, and broadband absorption capabilities have become a growing research hotspot. This work proposes a novel strategy for fabricating ceramic metamaterials based on ultraviolet（UV）-curable hyperbranched polysilazane（UV-PSN） precursors. By introducing photosensitive groups into the ceramic precursor monomers and utilizing digital light processing（DLP） 3D printing technology, the synergistic regulation of microstructure and macroscopic morphology is successfully achieved. The fabricated SiCN ceramic metamaterials not only exhibit high-temperature resistance up to 1400 ℃ and tunable dielectric properties but also demonstrate excellent manufacturing precision. In addition, the unique hollow structure design significantly enhances the impedance matching performance of the overall SiCN ceramic material, achieving an effective absorption bandwidth of 3.4 GHz in the X-band. Furthermore, the overall weight of the SiCN ceramic metamaterials is reduced by 79.6% compared to solid structures. This study provides new design concepts and technical pathways for developing multifunctional EMW absorbing materials suitable for extreme environments.

High-temperature microwave-absorbing materials play a crucial role in enhancing the stealth capabilities of hot-end components in advanced warplanes. Among them, Al₂O₃ and Ti₃SiC₂ have a wide range of applications in this field. However, the two powders have poor fluidity after physical mixing, which makes them difficult to use directly for plasma spraying, so secondary granulation is required. In this research, agglomerated powders composed of Al₂O₃ and Ti₃SiC₂ are successfully prepared using centrifugal spray drying. The study indicates the influence of various factors, including slurry solid content, PVA solution content, spray disk rotational speed, inlet air temperature, and outlet air temperature, on the morphology, surface roughness, and particle size distribution of the agglomerated powders.The results show that optimizing the content of solid and PVA in the slurry is beneficial to improve the sphericity and surface roughness of the powder, controlling the rotational speed of the spray disk can effectively control the particle size distribution of the powder, and a reasonable inlet/outlet temperature will help to further improvement of the sphericity of the powder. Optimal conditions for producing high-quality agglomerated powders are: 60% solid content, 3% PVA solution content, a spray disk rotational speed of 40 r·min⁻¹, an inlet air temperature of 250 ℃, and an outlet air temperature of 130 ℃. Under these conditions, the agglomerated powders exhibit high sphericity, low surface roughness, a bulk density of 1.92 g·cm⁻³, a fluidity of 37.1 s/50 g, and a tightly concentrated particle size distribution（D₁₀ = 30.1 μm, D₅₀ = 56.7 μm, and D₉₀ = 90.1 μm）. These powders, obtained through this method, can be directly utilized in plasma spraying and are suitable for large-scale production, thereby holding significant promise for the research and development of high-temperature wave-absorbing materials based on Al₂O₃ and Ti₃SiC₂.

With the rapid development of detection technology, the demand for infrared stealth performance in weapons and equipment is increasing, especially the urgent need to suppress the infrared radiation signal of high-temperature components. Pt metal films have ultra-low infrared emissivity, However, due to the diffusion of metal films with matrix elements at high temperatures, the infrared emissivity increases significantly. Therefore, it is necessary to prepare a barrier layer with high temperature stability. An alumina thin film barrier layer is prepared using magnetron sputtering and electron beam vapor deposition processes, respectively. The microstructure, phase composition of alumina thin films prepared by different processes and variation of emissivity after magnetron sputtering Pt coating on alumina thin films are studied by SEM and XRD. The results indicate that the alumina films prepared by electron beam vapor deposition process have a stable crystal structure. After surface coating with Pt metal film, the initial infrared emissivity of the film is 0.16. After high-temperature treatment at 900 ℃ for 20 h, the infrared emissivity is 0.172. It has good high-temperature resistance and is expected to be applied as a barrier layer for high-temperature and low infrared emissivity films.

To study the effect of spraying process parameters on the performance of Al₂O₃-SiC coatings, orthogonal tests are carried out to optimize the spraying process parameters, and the relationship between “spraying process- structure- bonding strength and thermal shock resistance” is established. The results show that the spraying power, powder feeding rate and spraying distance have no effect on the type of phases within the coating but significantly impact the coating quality and bonding strength. When the spraying power is 47 kW, the powder feeding rate is 30%, and the spraying distance is 110 mm, the coating bonding strength is the highest （10.51 MPa） and the porosity is the lowest（34.35%）. Thermal shock tests show that the coating does not fall off after 200 cycles at 900 ℃ and 1000 ℃, and the phases do not change. However, as the temperature is increased to 1100 ℃ and 1200 ℃, partial oxidative decomposition of SiC within the coating occurs, generating Si, C, SiO₂ and Al₆Si₂O₁₃, thus leading to coating peeling off due to the accumulation of thermal stress and the thickening of the thermally grown oxide (TGO) layer. The coating failure mechanism mainly originates from the thermal expansion coefficient mismatch between the ceramic layer and the bonding layer, the abnormal grain coarsening of the TGO layer, and the internal crack extension.

Radar serves as the “eye” of aircraft, playing a crucial role in aircraft guidance and thus necessitating protection by radomes. Given that radar components are primarily positioned at the aircraft’s nose and work in a complex environment, radome materials must exhibit high wave transparency, rain erosion resistance, impact resilience, and antistatic properties. However, the prevailing radome material, glass fiber reinforced plastic composites, falls short in terms of rain erosion resistance and antistatic performance. Rain erosion and electrostatic accumulation can disrupt radar signal transmission, ultimately compromising flight safety. Consequently, the application of rain-erosion-resistant and antistatic coatings emerges as an effective protective measure. This paper reviews the characteristics and current research status of aircraft radome coating systems globally and domestically, while also projecting the development and research directions of coating materials. Initially, the paper analyses the performance requirements for coatings based on the unique service environment of aircraft radomes. It then delves into the structural characteristics, protection mechanisms, and international research advancements of rain-erosion-resistant and antistatic coating systems. Domestic research into aircraft radome coating materials has a relatively late onset. These coatings have evolved from inelastic formulations to polyurethane elastic coatings, with further refinements and optimizations to the polyurethane resin enhancing weather resistance. In the realm of antistatic coatings, ongoing challenges include balancing electrical conductivity and dielectric properties while ensuring coating performance stability. Conclusively, the paper briefly analyzes the development key point of aircraft radome coating materials. It points out for future in-depth research focusing on three areas: the correlation between coating material properties and environmental factors, the damage and failure mechanisms of coating materials, and the compatibility of multifunctional coating materials.

The high-temperature mechanical properties of cast nickel-based superalloy K4222 enhance through alloying of Hf. This work investigates the effect of adding mass fraction of 0.72% and 1.5%Hf on the microstructure and high-temperature stress rupture properties of the alloy. The results reveal that the addition of Hf not only increases the MC carbide content in the alloy, but also facilitates the formation of eutectic （Ni₅Hf + γ） phases. After heat treatment, M₂₃C₆ carbides are dissolved at high temperature and MC carbides are degraded, resulting in an overall reduction in the carbide content of each alloy and the elimination of eutectic phases. However, a small amount of Ni₅Hf phase remains in the 1.5%Hf alloy. Meanwhile, the results show that Hf can greatly improve the stress rupture life of the alloy. Compared with 0%Hf alloy, the stress rupture life of the 0.72%Hf and 1.5%Hf alloys increases 101.4% and 211.2% under the condition of 899 ℃/172 MPa, respectively. The improvement of Hf content will reduce the rupture plasticity of K4222 alloy to a certain extent, but 0.72%Hf still maintains good level. Further analysis shows that the addition of Hf can change the morphology of carbides, increase the grain boundary strength, reduce the occurrence of carbide cracking and intergranular cracks, and thus improve the high-temperature creep strength of the alloy.

Heat treatment is the most critical thermal process determining the properties of powder metallurgy（PM）superalloy components, with FGH96 currently being one of the most prevalent PM Ni-based superalloys. This work investigates the effects of two distinct solution heat treatment cooling methods—full air cooling quenching and combined air-oil cooling quenching—on the microstructure and properties of FGH96 alloy ring parts. The results indicate that both cooling methods yield equivalent grain sizes, ranging from grade 6.5 to 7. Notably, full air-cooled rings exhibit more homogeneous distribution of secondary γʹ phase. In contrast, rings subjected to combined air-oil cooling exhibit coarser secondary γʹ phases, with reduced quantity on the inner side compared to the outer side, attributable to internally diminished cooling rate. During the later stage of quenching, ring parts undergoing full air cooling experience a slower cooling rate than those using combined air-oil cooling. Furthermore, fine γʹ phases, possessing sizes between the secondary and tertiary γʹ phases, precipitate along the grain boundaries using full air cooling method, leading to grain boundary strengthening. This enhances tensile strength but reduces elongation and plastic elongation at 68 h in high-temperature creep tests. Additionally, due to the more uniform cooling rate throughout the ring during full air cooling quenching, the surface residual stress reduces with more uniform distribution, thereby augmenting dimensional stability during subsequent machining processes.

Based on hot compression tests of GH738 superalloy, encompassing deformation temperatures ranging from 980 ℃ to 1100 ℃ and strain rates of 0.001-0.1 s⁻¹, deformation activation energy（Q）, temperature-compensated strain factor（lnZ）, power dissipation efficiency（η） and instability factor（$ \xi (\dot{\varepsilon })$） are calculated. Subsequently, a response surface model is established, utilizing hot deformation processing parameters as input variables and targeting Q, lnZ, η and $ \xi (\dot{\varepsilon })$ as output metrics. This model facilitates the optimization of the superalloy’s heat deformation processing parameters. The results show that the superalloy’s flow stress exhibits considerable sensitivity to variations in these parameters, which significantly impact Q, lnZ, η and $ \xi (\dot{\varepsilon })$. Notably, the established response surface model demonstrates exceptional prediction accuracy, with average absolute relative errors of 0.494%, 0.564%, 0.919% and 13.484% for Q, lnZ, η and $ \xi (\dot{\varepsilon })$, respectively. Employing multi-objective optimization—aiming for low Q and lnZ coupled with high η and $ \xi (\dot{\varepsilon })$—the optimal deformation processing parameters are determined to within the range of 1092-1100 ℃ deformation temperatures and 0.001-0.0056 s⁻¹ strain rates. Microstructural analysis conducted under these optimized parameters further validates the accuracy of the multi-objective optimized results.

The ultra-thick 7050-T7451 plates, which are commonly utilized in the primary load-bearing components of aerospace structures, confront a challenge: a discrepancy in properties along their thickness directions. To unravel the hidden principles governing this phenomenon, a comprehensive suit of tests and characterization techniques is employed on δ155 mm ultra-thick 7050-T7451 plate. These techniques encompass conventional tensile tests, plane strain fracture toughness tests, as well as imaging methods such as optical microscopy（OM）, scanning electron microscopy（SEM）, electron backscatter diffraction（EBSD） and transmission electron microscopy（TEM）. Samples for property testing and microstructure characterization are extracted from different thickness regions along different directions. The results of the property testing reveal that the tensile properties at different thickness regions along L direction are similar. However, in LT direction, T/4 thickness region exhibits higher tensile strength compared to T/2 thickness region. Conversely, the fracture toughness of T/2 thickness region surpasses T/4 thickness region in both directions, with more pronounced difference observed in L-T direction. Microstructural observations demonstrate that the fracture surface morphology of small cleavage fractures at T/4 thickness region converts to transgranular slip at T/2 thickness region. As the thickness region transferring from T/4 to T/2, grain morphologies and texture types vary obviously, while the types and distribution of precipitated phases remain consistent. The texture types are numerous and dispersed at T/4 thickness region with a small grain size and a large amount of sub-grains. The texture types are mainly recrystallization R-Brass texture {111}〈112〉 at T/2 thickness region with a big grain size but a decrease in sub-grain quantity. Along grain and sub-grain boundaries, coarse η precipitation phases and precipitate free zones are observed, while numerous η' precipitate phases are detected within the grains. The disparities in macrostructure and microstructure between the thickness regions from T/4 to T/2 stem from variations in the texture types and quantities of sub-grain boundaries. This factor also influences the plastic deformation zone at crack tips and crack propagation paths, ultimately determining differences of the tensile strength and fracture toughness.

As a new type of aviation material, fiber/aluminum-lithium（Al-Li）laminates are significantly threatened by fatigue cracks. In other words, fatigue cracks are the “fatal killers”, which leads to their failure. The combined effect of service overload and laminated structure leads to bridging-overload interaction phenomenon, which makes the crack growth mechanism complex and performance characterize difficult. To solve this problem, the crack growth behavior in fiber/Al-Li laminates under fatigue single-peak compressive overload are analyzed and predicted, which is under typical flight loading condition. Firstly, according to the loading characteristics from Mini-Twist spectrum, fatigue crack growth tests under constant amplitude fatigue loading and single-peak compressive overload conditions with varying overload ratios are designed and conducted. Secondly, a comparison of the（a-da/dN）data under constant amplitude fatigue loading and single-peak compressive overload with different overload ratios is made, which is under the same stress level. By analyzing the data, it finds when the overload ratio is greater than a certain value, the crack growth rate of the laminate shows a significant accelerated growth effect. Thirdly, based on the characteristics of crack growth for laminates, the equivalent crack length model of crack growth is improved for laminates. By combing with the incremental plastic damage theory, crack growth rate under fatigue compressive overload is characterized. And a prediction model of fatigue crack growth for fiber/metal laminates under single-peak compressive overload is established. Finally, the effectiveness of model is validated by comparing with the experiment data.

The ignition temperature serves as a pivotal parameter for assessing the flame retardancy of high-temperature titanium aluminum alloys（TiAl alloys）. Nevertheless, accurately predicting the ignition temperature of TiAl alloys remains a formidable challenge. Leveraging the Frank-Kamenetskii and Coulomb friction models, this paper develops a computational framework to determine the critical ignition temperature of TiAl alloy. It further investigates the influences of flow velocity, friction contact pressure, and oxygen partial pressure on this critical temperature. The findings reveal that as the flow velocity escalates from 140 m/s to 340 m/s, the critical ignition temperature incrementally rises from 1699.0 K to 1751.6 K. Intriguingly, while friction contact pressure increases from 1.0 MPa to 3.9 MPa, the critical ignition temperature stabilizes at 1710.2 K; however, the threshold ambient temperature necessary for alloy combustion decreases linearly, spanning from 1363.0 K to 537.5 K. Conversely, as the oxygen partial pressure climbs from 21.3 kPa to 96.3 kPa, the critical ignition temperature diminishes from 1719.7 K to 1665.8 K. Under specific conditions of an air flow temperature of 298 K and an air flow rate of 4.1 g/s, the finite volume method calculates a maximum flow velocity of 155.1 m/s near the specimen surface within the combustion chamber. Notably, the computed and experimental values for the critical oxygen partial pressure required for ignition are 93.8 kPa and 88.2 kPa, respectively, exhibiting a relative error of 6.3%.

“In-situ alloying” facilitates agile and swift adjustments to alloy compositions, thereby unlocking a multitude of prospects for developing novel alloys with distinctive microstructures. In this study, TC4-x316L alloys（with x=1%, 3%, and 5% by mass） are fabricated through the combination of selective laser melting（SLM） and the in-situ alloying approach. The effects of varying concentrations and SLM process parameters, including scanning rate and laser power, on the microstructural characteristics and mechanical properties of the alloys are investigated using metallographic microscopy（OM）, scanning electron microscopy（SEM）, XRD, and tensile testing. The results indicate that an increase in 316L content refines the alloy’s microstructure, causing the martensitic α′ phase to transform into the β phase. The alloy’s hardness initially rises and then decreases slightly, while its strength peaks at an x value of 1%. Specifically, when the laser power is set to 175 W and the scanning rate to 1000 mm/s, the TC4-1%316L alloy exhibits a yield strength of 1200 MPa, a tensile strength of 1425 MPa, and an elongation at break of 6.8%.

The laser shock adhesion test serves as a reliable method for assessing the interface properties of multi-interface materials, with a profound understanding of the interface damage mechanism under laser shock. In this paper, the damage mechanism at the adhesive interface between metal and fiber composites within titanium-based carbon-fiber/epoxy laminates（Ti-CF FMLs） is investigated. The influence of laser shock parameters on interface damage of laminates is studied by analyzing the cross-section morphologies and measuring interface tensile strength. Additionally, a finite element simulation model is established to pinpoint the laser spot location causing maximal damage to the adhesive interface, and the impact of specimen constraint mode on interface damage is explored. The results show that as laser power density increases from 1.2 GW/cm² to 7.2 GW/cm², the interfacial tensile strength of 2/1 Ti-CF FMLs decreases from 2.92 MPa to 0.11 MPa, while for 3/2 Ti-CF FMLs, it decreases from 0.14 MPa to 0.015 MPa. For 2/1 Ti-CF FMLs, the peak interface damage consistently appears on the unimpacted side, whereas for 3/2 Ti-CF FMLs, it progressively shifts upwards to the third layer. When the laser spot’s center is positioned 1.5 mm from the lamellar plate boundary, interface damage peaks at 0.75. Applying constraints to the specimen’s back surface markedly reduces damage compared to unconstrained specimens. Analysis of the Ti-CF FMLs’interface damage process reveals that the site of maximal damage correlates with the intersection of the reflected and incident unloading waves propagating from the front towards the free surface.

Under prolonged operational conditions, the servo motor housing is prone to developing numerous fatigue cracks, which compromise its structural integrity and service lifespan. To address this issue, we apply a fatigue life prediction method rooted in small crack theory to the servo motor housing, while also exploring innovative approaches for damage tolerance design and life prediction. This study conducts extensive tests on the propagation of both long and small cracks in the L-T and T-L directions at room temperature, utilizing 7050 aluminum alloy single-sided notch tensile specimens. Based on the propagation data of small and long cracks, the da/dN-ΔK data of crack propagation are obtained by fitting. Scanning electron microscopy（SEM） is used to conduct microscopic analysis of the specimen’s fracture surface and to quantitatively assess the material’s initial defects. Based on the initial crack size and crack propagation data, the three-dimensional crack propagation theory analysis method based on fracture mechanics and the finite element simulation method of ABAQUS-Franc3D software are used to predict the fatigue life of the servo housing. The predicted results are evaluated using the actual fatigue life, and the predicted and experimental results are in good agreement.