Electromagnetic Wave Absorption Research Articles

Synergistic design of C/SiC@SiC aerogel for enhanced thermal insulation and electromagnetic wave absorption

High-performance SiC aerogels are sought after for their superior thermal insulation and absorption properties, especially in applications such as electromagnetic stealth for aero engines and high-temperature radar stealth. However, achieving SiC aerogel with both temperature resistance and strong wave absorption while controlling their properties remains a significant challenge. This study investigates the influence of reactant concentrations on the structure, thermal insulation, and absorption performance of SiC aerogels synthesized via the sol-gel method. The aerogel synthesized with a n(C):n(Si) ratio of 1:2 showed superior thermal insulation. Additionally, it showed excellent electromagnetic wave absorption, with a minimum reflection loss of −53.80 dB at 6.16 GHz and a maximum effective absorption bandwidth of 3.10 GHz at a thickness of 2.40 mm. Furthermore, the maximum compressive strength of C/SiC@SiC reached 0.98 MPa, a notable improvement of 81.48 % compared to the pristine C/SiC matrix. The maximum effective absorption bandwidth of C/SiC@SiC was increased to 6.06 GHz at 2.35 mm, and the surface center temperature decreased from 183.1 °C for C/SiC to 130.1 °C for C/SiC@SiC. Overall, this study offers valuable insights into the development of advanced absorption and thermal insulation materials, providing a foundation for further research and innovation in this field.

Facile and scalable preparation of gradient multilayer nanocomposite structure with preeminent microwave absorption and radar cross section reduction capability

The pressing need for the enhancement of stealth materials that are harmonious with state-of-the-art military equipment is critical, as it plays a pivotal role in bolstering the survivability and operational capabilities of advanced military technology. This research offers a straightforward approach for fabricating a gradient triple-layer absorber utilizing a Cu2O/h-BN nanocomposite and FeCoNi magnetic compounds, characterized by reduced thickness, designed for X-band wave spectrum attenuation purposes. The primary objective of this study is to examine the electromagnetic wave absorption characteristics of single-layer samples and subsequently develop a triple-layer gradient sample with distinct electromagnetic wave stealth features based on the findings. Optimal performance was observed in the gradient sample, where Cu2O/h-BN nanocomposite with 20 and 10 wt% was incorporated as a matching layer with thicknesses of 0.5 and 0.5 mm, respectively, and FeCoNi with 20 wt% was employed as an absorbing layer with a 0.4 mm thickness, surpassing the performance of the other samples. The optimal sample achieves a dissipation loss of −45.6 dB and a bandwidth of 2.9 GHz, all while maintaining a total thickness of just 1.4 mm. Facilitating multiple heterogeneous interfaces among layers, substances, and the synergistic interaction between constituent elements and layers’ thickness and arrangement enable this gradient configuration to demonstrate exceptional performance in radar stealth compatibility.

Cotton fiber-derived carbon decorated with MoS2 for high electromagnetic wave absorption

Biomass-derived carbon materials have advantages such as lightweight and strong sustainability compared with traditional carbon-based absorbing materials, thus having great potential in electromagnetic wave (EMW) absorbing materials. CFC/MoS2 composites with a structure of cotton fiber-derived carbon (CFC) decorated with molybdenum disulfide (MoS2) have been prepared using the simple carbonization and hydrothermal method in this work, which had high EMW absorption. The analysis results indicate that high EMW absorption of CFC/MoS2 composites is attributed to the balanced impedance matching, while being affected by a combination of conductive loss, multiple scattering, and polarization loss. The minimum reflection loss of CFC/MoS2 composite with thickness of 3.0 mm could reach −49.7 dB and effective bandwidth could reach 3.6 GHz (8.0–11.6 GHz) at a frequency of 9.25 GHz. This work fully utilizes the advantages of biomass-derived carbon and proposes a novel research approach for development of environmentally friendly and low-cost EMW absorbing composites.

Novel cable‐like tin@carbon whiskers derived from the Ti2SnC MAX phase for ultra‐wideband electromagnetic wave absorption

AbstractOne‐dimensional (1D) metals are well known for their exceptional conductivity and their ease of formation of interconnected networks that facilitate electron migration, making them promising candidates for electromagnetic (EM) attenuation. However, the impedance mismatch from high conductivity and their singular mode of energy loss hinder effective EM wave dissipation. Construction of cable structures not only optimizes impedance matching but also introduces a multitude of heterojunctions, increasing attenuation modes and potentially enhancing EM wave absorption (EMA) performance. Herein, we showcase the scalable synthesis of tin (Sn) whiskers from a Ti2SnC MAX phase precursor, followed by creation of a 1D tin@carbon (Sn@C) cable structure through polymerization of PDA on their surface and annealing in argon. The EMA capabilities of Sn@C significantly surpass those of uncoated Sn whiskers, with an effective absorption bandwidth reaching 7.4 GHz. Remarkably, its maximum radar cross section reduction value of 27.85 dB m2 indicates its exceptional stealth capabilities. The enhanced EMA performance is first attributed to optimized impedance matching, and furthermore, the Sn@C cable structures have rich SnO2/C and Sn/SnO2 heterointerfaces and the associated defects, which increase interfacial and defect‐induced polarization losses, as visually demonstrated by off‐axis electron holography. The development of the Sn@C cable structure represents a notable advancement in broadening the scope of materials with potential applications in stealth technology, and this study also contributes to the understanding of how heterojunctions can improve EMA performance.

Activating Excellent Electromagnetic Wave Absorption of Micromorphology-Optimized Cu/C Nanocomposite Fibers via a Metal-Organic Framework Template-Assisted Strategy.

Morphological engineering is crucial for conceiving high-efficiency electromagnetic wave (EMW) absorption materials. However, for carbon fiber-based composites, the management of micromorphology is significantly astricted by complex fabrication. It remains highly challenging to clarify the micromorphological influences on the EMW loss mechanism of carbon fiber-based absorption materials. In this work, micromorphology-optimized Cu/C nanocomposite fibers are prepared by virtue of a metal-organic framework (MOF) template-assisted strategy. Through skillfully grafting the morphology-regulation capacity of MOFs onto composite fibers, the Oswald maturation and particle distribution issues of Cu nanoparticles are settled, and the efficient electron transport pathways are established by the bead-like structure of the fiber matrix. Compared to prepared conventional Cu/C nanocomposite fibers, the MOF template-assisted strategy stimulates a remarkable leap in EMW absorption performance. The minimum reflection loss value of Cu/C-40 can reach -64.5 dB, 15.96 times lower than that of a conventional sample (Cu/C-2). The maximum effective absorption bandwidth extends to 6.08 GHz, contrasting the ineffective performance of Cu/C-2. Systematic research demonstrates that the enabled graphite-catalytic function of Cu nanoparticles collaborated with an optimized conductive network structure plays a pivotal role in creating field-induced leakage currents, facilitating conductive loss, the primary contributor to EMW dissipation. This work establishes a correlation mechanism between micromorphology and EMW loss, presenting a compelling example of customizable carbon fiber-based absorbers.

RGO aerogel embedded with organic–inorganic hybrid perovskite for lightweight broadband electromagnetic wave absorption

rGO aerogel embedded with organic–inorganic hybrid perovskite for lightweight broadband electromagnetic wave absorption

A novel oxide ceramic matrix composite with integrated high-temperature EMW absorption and mechanical performance

Oxide ceramic matrix composites (OCMC) are extensively used as thermal structural materials due to good high-temperature resistance, mechanical properties, and oxidation resistance, but they are rarely regarded as electromagnetic wave absorbing materials due to the high resistivity of oxide ceramics/fibers. However, high-performance Al2O3 fiber can be used to design and fabricate OCMC with integrated high-temperature microwave absorbing and mechanical properties by introducing dielectric material into Si-based ceramic matrix. The N610/Si3N4-SiOC composites have the prior mechanical performance because the uniformly distributed Si3N4 matrix made the fiber bear effectively. After that, the Sc2O3 modified SiOC matrix was filled into inter- and intra-fascicular pores forming interfacial polarization, dipole polarization, multiple reflection and scattering to attenuate the incident electromagnetic wave (EMW). The effective absorption bandwidth (EAB) and the minimum reflection coefficient (RCmin) of N610/Si3N4-SiOC(Sc) composites at the thickness of 2.75 mm reach 3.0 GHz and −42 dB in the X band, respectively. In addition, the EMW absorption performance of the composite is relatively stable with EABmax and RCmin of 3.5 GHz and −41 dB in 4–18 GHz at high temperatures. This work provides a strategy for designing and fabricating OCMC with excellent mechanical properties and EMW absorption properties.

Multi-component attached carbon matrix composites with superior electromagnetic wave absorption performance and multifunctional applications

The preparation of highly absorbing and high-performance electromagnetic wave-absorbing materials remains a significant challenge. In this paper, carbon matrix composites modified with sodium inorganic salts (CMS) have been successfully prepared by using the solvent evaporation method in combination with the hydrothermal treatment and high temperature carbonization processes. The composition of the product can be manipulated by varying the material ratios, which in turn affects the interface and dielectric properties of the material. Sodium carbonate (Na2CO3) was produced as a transition phase between sodium silicate and carbon matrix due to high temperature. According to differential charge density a significant charge accumulation found between the interfacial of Na2CO3 and carbon layer is helpful to polarization. The synergistic effect of polarization and conduction loss due to the formation of multiple heterogeneous interfaces and carbon matrix results in excellent electromagnetic wave absorption performance. The minimum reflection loss (RLmin) is −55.49 dB when the thickness is 3.1 mm. Furthermore, CMS composites exhibit notable flame retardancy and thermal insulation properties, rendering them suitable for a diverse range of applications. These remarkable achievements provide new ideas for the design and development of efficient electromagnetic wave absorption materials.

Preparation of coal gangue foam concrete modified by nanomaterials: Physical properties, pore structure, and electromagnetic properties

In this study, coal gangue foam concrete (CGFC) was modified with nanomaterials to optimize its electromagnetic wave (EWV) absorption performance. Single-factor test was carried out to explore the effects of nano-silica (NS) and nano-calcium carbonate (NC) on the physical characteristics, hydration products and microstructure of CGFC. The results showed that the compressive strength of CGFC was the optimal when NS and NC were mixed with 1.5 wt% each, in which case the volume water absorption also decreased to the lowest value of 20.61 %. Additionally, compared with the control group, the incorporation of NS significantly accelerated the cement hydration rate. Moreover, the synergistic effect after the addition of NC promoted the cement hydration to generate more ettringite and C-S-H gel, and partly reduced the average pore size of CGFC, thereby improving the pore structure. Finally, the attenuation constant of the composite material can reach 187.92, and the reflection loss can reach −35.6 dB, demonstrating its excellent electromagnetic wave absorption ability.

Zirconium-modified hierarchical porous SiC-based nanofibrous aerogel with efficient electromagnetic waves absorption and thermal insulation properties

Supersonic aircraft require materials that can offer both thermal insulation and electromagnetic wave (EMW) absorption capabilities to facilitate flight operation in extremely high-temperature environments. Herein, zirconium modified SiC-based nanofibrous aerogels (ZSNFAs) with hierarchical pore stucture were prepared by electrospinning combined with carbothermal reduction reaction. The introduction of Zr formed a high-conductivity ZrC phase inside the fiber and significantly increased its conductivity loss, while the growth of SiC nanowires constructed a hierarchical porous structure within the aerogel, which not only promoted the interfacial polarization and multiple reflection losses of EMWs, but also impeded heat transfer and improved the compressive strength of the aerogel. The obtained ZSNFA demonstrated high mechanical robustness (∼0.32 MPa), low thermal conductivity (0.023–0.024 W·m−1·K−1), and superior EMW absorption performance (at 2 % Zr content, the minimum reflection is –60.72 dB and effective bandwidth of 4.5 GHz at 2.8 mm thickness), making it suitable for utilization in complex high-temperature environments.

Thin thickness electromagnetic wave absorbent: Fe3O4 decorated carbon nanofibers composite with designable 3D hierarchical architecture

Designable 3D hierarchical architecture with multi-component heterostructure has been built to form a connected network by fully utilizing the advantages of one-dimensional carbon nanofibers. Fe3O4 decorated carbon nanofibers, which exhibited core-shell microstructures, were successfully prepared by solvothermal and electrospinning technology. Their electromagnetic wave absorption (EWA) performances were explored. The morphology which determined the electromagnetic (EM) parameters can be controlled by adjusting the mass ratio of the raw material. The Fe3O4 decorated carbon nanofibers composite showed an excellent absorbing capability. At a thickness of 2.5 mm, the minimum reflection loss (RLmin) value was −28.28 dB. In particular, the widest effective absorption bandwidth (EAB) can reach up to 2.96 GHz at 1.5 mm. It was more surprising that the effective absorption (RL ≤ −10 dB) occurred when the thickness was only 1.0 mm. The absorption mechanism study revealed that the connected structure facilitated the formation of conductive networks, leading to conductive loss, multiple reflection and scatterings, and interfacial polarization loss. The defects that created during carbonization process enhanced the dipole polarization. The generated magnetic loss which mainly consisted of natural resonance and exchanged resonance loss enhanced the attenuation of EW. Moreover, good impedance matching resulting from the synergistic effect of composition and unique porous network also played an important role. The little filler loading and the thin thickness make the composite have a high EWA performance, which is promising for EWA applications.

Synthesis of Mo2C/C nanoclusters attached on rGO nanosheets for high-Efficiency electromagnetic wave absorption

It is an effective strategy that constructing composites with a multi-dimensional structure synergistically enhance their electromagnetic (EM) wave absorbing performance. Herein, a high-efficiency EM wave absorber of Mo2C/C nanoclusters uniformly encapsulated in rGO nanosheets (Mo2C/C-rGO) was prepared by a combination of the directing freeze-dry and subsequently carbothermal reaction method. Mo2C/C was in-situ induced from spherical phosphomolybdic acid/polypyrrole (PMo12/PPy) to result in a unique cluster-like microstructure. Abundant heterogeneous interfaces endowed the Mo2C/C-rGO composites with excellent EM wave absorption performance at a low filling ratio of 5 wt%. The minimum reflection loss (RL) value was −49.3 dB at 1.38 mm and the maximum effective absorption bandwidth (EAB, RL<-10 dB) was 5.12 GHz at 1.60 mm. The excellent performance was owing to the lamellar structure and abundant heterogeneous interfaces in Mo2C/C-rGO, lengthening the transmission path of the incident wave, as well as resulting in high conduction loss and interfacial polarization loss. This universal strategy would be extended to other absorbers with multi-interface structures for lightweight and broadband EM wave absorption.

γ-Radiation-induced in-situ formation of TiC/MXene nanocomposites for superior electromagnetic wave absorption

The layered structure of two-dimensional transition metal carbides/nitrides (MXenes) is potentially conducive to efficient electromagnetic wave absorption (EWA). However, Ti3C2Tx MXene typically encounters challenges with a narrow effective absorption bandwidth (EAB) due to impedance mismatch caused by its inherent high conductivity. This study employed γ-radiation to induce the in-situ formation of TiC/MXene nanocomposites for EWA. The radiation preparation process is carried out under reducing conditions at ambient temperature and pressure, effectively minimizing the risk of MXene oxidation while preserving its original layered structure. The resultant intercalated structure, featuring in-situ formed TiC nanoparticles embedded within the Ti3C2Tx MXene layers, facilitates the integration of layered conductive networks with abundant spatial gaps and multiple heterojunction interfaces. Leveraging these structural and chemical advantages, the composite demonstrates enhanced EWA capabilities. At a 50 wt% irradiated MXene loading, the material achieves an EAB of 6.08 GHz at 1.55 mm thickness and a minimum reflection loss (RLmin) of −51.1 dB at 3.95 mm. Compared to conventional composite fabrication methods, γ-radiation offers a more environmentally sustainable, efficient, and scalable approach. This research opens up a new avenue for exploiting the MXene family in EWA applications.

Constructing MXene-based mixed-dimensional structure with multiple interfaces to optimize dielectric-magnetic synergistic effect for effective electromagnetic wave absorption

Exploring efficient microwave absorbing materials (MAMs) which could convert electromagnetic (EM) energy into thermal energy represents an approbatory vision to reducing EM radiation and interference. Designing of mixed-dimensional structure with multiple interfaces represents the available target to investigate an ideal MAMs, which maximizes the superiority of mixed-dimensional structure in electromagnetic wave absorption (EMWA). Herein, we take full advantage of multiple interfaces engineering of MXene for optimizing the impedance matching to improve EMWA, MXene-based mixed-dimensional structure was designed by incorporating three-dimensional Fe3C@Carbon layers coated zero-dimensional Fe3O4 nanoparticles (NPs) supported two-dimensional MXene nanosheets (MXene/Fe3O4@Fe3C@Carbon, MFC). The Fe3O4@Fe3C@C with Core@shell structure arrests the essentially self-restacked of MXene and provides various attenuation mechanisms for the incident electromagnetic waves (EMWs). By regulating the carbonization temperature, the MFC exhibits enhanced EMWA property which is attributed to the characteristic structure and optimized dielectric-magnetic synergy effect. The minimum reflection loss (RLmin) value of MFC can reach to −64.3 dB with a matching thickness of 1.73 mm. Otherwise, the maximum effective absorption bandwidth (EAB) (RLmin < -10 dB) reaches 6.42 GHz at only 1.5 mm. Thus, our study refers a novel-fire enlighten to develop excellent mixed-dimensional microwave absorbent based on MXene.

Low-frequency and broadband electromagnetic wave absorption mechanism of (Hf0.2Zr0.2Ti0.2Ce0.2La0.2)C1-δ/PyC microspheres with hierarchy pores from 4 GHz to 17 GHz

Achieving low-frequency broadband electromagnetic wave absorption in extreme environments over 2000 °C is challenging. Biomimetic hierarchy materials of high entropy lanthanide carbides were designed to optimize electromagnetic wave absorption. Composite microspheres of (Hf0.2Zr0.2Ti0.2Ce0.2La0.2)C1-δ and SiC embedded in pyrolytic carbon (MC/PyC) were prepared by using the electro-spray method followed by heat treatment. The specimens of MC/PyC microspheres with a thickness of 2.5 mm exhibited a minimum reflection loss value of − 48.9 dB, and electromagnetic wave absorption from 4.0 GHz to 17 GHz. The enhanced absorption capability is attributed to the synergistic effect of dielectric losses from conduction and polarization, along with magnetic losses due to eddy currents and natural resonance of the high-entropy carbides within the multiscale pores. The composition and featured microstructure MC/PyC microspheres were noteworthily stable under the 2200 °C oxyacetylene ablation, ensuring consistent high-performance electromagnetic wave absorption even in harsh conditions.

Wigner Function Method for Describing Electromagnetic Field in Plasma-Like Media with Spatial Dispersion and Resonant Dissipation

The paper gives a systematic presentation of the Wigner function method (Weyl formalism) for modeling the propagation and absorption of electromagnetic waves in anisotropic and gyrotropic dissipative media with spatial dispersion. A general kinetic equation for the Wigner function (tensor) is formulated, and its asymptotic expansion up to the second order for smoothly inhomogeneous and weakly dissipative media is constructed. As a result, a modification of the method of the kinetic equation for rays is proposed, based on the stochastic description of rays, making it possible to increase the accuracy of numerical modeling of wave problems with strong transverse inhomogeneity of the absorption coefficient without increasing the amount of calculations. The technique developed can be used to describe the propagation, absorption, and scattering of electron-cyclotron waves in high-temperature plasma of magnetic traps for controlled fusion in cases where standard modeling methods do not provide the necessary accuracy.

3D high-temperature resistance BaTiO3/EG hybrids with enhanced EMWs absorption capacity

BaTiO3 is a promising electromagnetic waves (EMWs) absorption material due to its chemical stability and large dielectric constant. However, the high reflection coefficient of pure BaTiO3 at high frequencies reduced its EMWs absorption capacity. To resolve the issue, BaTiO3/expanded graphite (EG) hybrids were successfully synthesized by high-energy ultrasound assisted heat treatment technology. The combination of BaTiO3 particles and layered EG formed three-dimensional (3D) heterostructure of BaTiO3/EG hybrids, which optimized the impedance matching. Abundant conductive network enhanced interfacial polarization, numerous interface defects and multiple reflections together promoted the attenuation of EMWs. At the molar ratio of 0.2:0.8 between BaTiO3 and EG, the BaTiO3/EG sample with 1.5 mm match thickness displayed −100.6 dB of minimum reflection loss (RLmin) and 5.9 GHz of effective absorption bandwidth (EAB). In addition, the ceramic character of BaTiO3/EG hybrids endowed them excellent high-temperature stability.

Construction of periodic hollow SiC microtube ceramic for synergistic broadband absorption performance at elevated temperatures

Silicon carbide (SiC) has been utilized as a semiconductor material and has been shaped into various structural forms to obtain outstanding electromagnetic wave (EMW) absorption properties, characterized by low weight and excellent absorption capabilities even at high temperatures. A chemical vapor infiltration (CVI) approach was used to synthesis a periodic structured SiC microtube ceramic on a carbon fiber plain preform, taking inspiration from the porous structure found in SiC materials. Afterwards, the carbon fibers were removed by oxidation at a temperature of 900 °C. The periodic structural SiC microtube ceramic exhibited a porosity above 68 %, rendering it a lightweight material possessing a density of 0.8 g/cm3. The SiC microtube ceramic displays a periodic structure and exhibits anisotropy at 0° and 45°, respectively, as a result of the braided structure of the fiber fabric. When evaluated at a 0° angle of incidence, the SiC microtube ceramic, with a thickness ranging from 2.4 to 2.6 mm, showed excellent absorption of EMW energy in the Ku-band frequency range, attenuating more than 90 % of the energy, with a minimum reflection loss of −56.36 dB at 15.65 GHz. SiC microtube ceramics have demonstrated an effective absorption bandwidth exceeding 8.2 GHz throughout a temperature range of ambient temperature to 600 °C, with a thickness of 2.8 mm. Furthermore, the SiC microtube ceramic exhibited stable EMW absorption properties and thermal conductivity even at temperatures as high as 600 °C.

High-performance electromagnetic wave absorption in VS2@multi-walled carbon nanotube composites

In this work, composites comprising VS2 and multi-walled carbon nanotubes (MWCNTs) were prepared using a simple hydrothermal method. The MWCNTs were dispersed among the VS2 nanosheets, which produced dipole polarization and interfacial polarization, thus enhancing the dielectric loss. Meanwhile, the electrical conductivity of the composites gradually increased with the rising content of the MWCNTs, which improved the electromagnetic wave absorption performance. By adjusting the mass ratio of VS2 to MWCNTs to 5:1, a minimum reflection loss value (RL) of −24.7 dB was achieved with a thickness of only 1.3 mm at a frequency of 14.4 GHz. Besides, when the thickness was reduced to 1.2 mm, the effective absorption bandwidth extended to 3.75 GHz. The results suggest that impedance matching and the synergistic effect of multiple loss mechanisms contribute to the excellent electromagnetic wave absorption performance of the materials. Consequently, the VS2/MWCNTs composites exhibit simple synthesis, wide absorption bandwidth, thin thickness, and high absorption capacity, rendering them a promising material for practical microwave absorption applications.

Synthesis of SiOC@C ceramic nanospheres with tunable electromagnetic wave absorption performance

Synthesis of SiOC@C ceramic nanospheres with tunable electromagnetic wave absorption performance