Electromagnetic Materials Research Articles

Mechanical properties and electromagnetic wave absorption characteristics of solid waste low-carbon cementitious materials

A low-carbon multi-functional cement substitute material has been developed to reduce electromagnetic pollution in building spaces and protect human health. The solid waste electromagnetic absorption cementitious material (SWEACM) is produced by combining steel slag (SS), blast furnace slag (BFS), and phosphogypsum (PG). In this study, the properties of SWEACM were analyzed, including flow, electromagnetic wave absorption, strength, and environmental properties. Additionally, the hydration and electromagnetic wave absorption mechanisms were examined. The results indicate that SS, BFS, and PG content significantly affect the strength and electromagnetic wave absorption properties of SWEACM. S-6 exhibits the best overall performance (SS: BFS: PG = 3:6:1), with the highest strength (28 days compressive strength = 33.5 MPa) and fluidity (19.1 cm). Furthermore, it has excellent electromagnetic absorption performance (RLmin = −45.4 dB), with an adequate absorption bandwidth of up to 10 GHz in the 2–18 GHz range. The excellent electromagnetic wave absorption capability of SWEACM is mainly due to the resonance, polarization relaxation loss, and conduction loss of the magnetic and conductive components in the material. The results show that SWEACM can be used as a multi-functional construction engineering material for electromagnetic protection, combining high levels of high electromagnetic wave absorption, strength performance, and environmental benefits.

Electromagnetic shielding materials of highly conductive PVA/PAA/hydrogel cross-linked with MXene

MXene-based materials that effectively deal with harmful electromagnetic waves are attracting more and more attention. In this paper, MXene hydrogels with good properties were prepared using polyvinyl alcohol (PVA) and polyacrylic acid (PAA) to construct a three-dimensional framework for hydrogels, and then adding homemade MXene materials to take advantage of their excellent properties, which resulted in the formation of an electrically conductive framework. The study shows that MXene-10 has a tensile strength of 0.29 MPa and an electrical conductivity of 156.24 S/mm. In addition, electromagnetic shielding (EMI) of 33.6 dB can be achieved when the MXene hydrogel is only 2 mm.

Intelligent Tunable Wave-Absorbing CNTs/VO2/ANF Composite Aerogels Based on Temperature-Driving.

The development of new electromagnetic absorbing materials is the main strategy to address electromagnetic radiation. Once traditional electromagnetic wave-absorbing materials are prepared, it is difficult to dynamically change their electromagnetic wave-absorbing performance. Facing the complexity of the information age and the rapid development of modern radar, it is significant to develop intelligent modulation of electromagnetic wave-absorbing materials. Here, CNTs/VO2/ANF composite aerogels with dynamic frequency tunability and switchable absorption on/off were synthesized. Based on the phase change behavior of VO2, the degree of polarization and interfacial effects of multiple heterogeneous interfaces between VO2 and CNTs and aramid nanofibers (ANFs) were modulated at different temperatures. With the increase in temperature (from 25 to 200 °C), the maximum absorption frequency of the frequency tunable aerogel is modulated from 12.24 to 8.56 GHz in the X-band, and the absorption intensity remains stable. The maximum effective switching bandwidth (ΔEAB) of the wave-absorbing switchable aerogel is 3.70 GHz. This study provides insights into intelligent electromagnetic wave absorption performance and paves the way for temperature-driven application of intelligent modulation of electromagnetic absorbers.

FeCo/PANI composites as electromagnetic shields in the X-band: An understanding of the loss mechanisms

The growing dependence on electronic devices functioning within the microwave frequency range, coupled with the need for miniaturization, has resulted in increased instances of electromagnetic interference (EMI) in such devices. Besides altering device performance, the associated health hazards due to electromagnetic radiations have necessitated the urgency for developing efficient electromagnetic shielding materials. Here, highly magnetic FeCo nanoparticles, approximately 200 nm in diameter, have been used as magnetic filler materials in emeraldine base (PANI – EB) and emeraldine salt (PANI – ES) forms of polyaniline to understand the EMI shielding response in X-band frequency range (8.2–12.4 GHz). Composites using 10 % and 25 % FeCo by weight have been prepared using a physical mixing approach and uniform dispersion within the polymer matrix is ascertained using FE-SEM imaging and EDX elemental maps. Structural and magnetic properties of FeCo remain unaltered after the grind mixing process, as confirmed by XRD and VSM measurements. With the total shielding effectiveness remaining sufficiently low at 2–3 dB in FeCo/PANI – EB, significant enhancement to up to 40 dB is achieved in composites prepared in PANI – ES. Detailed investigations of electromagnetic parameters of the composites reveal the importance of the magnetic filler to achieve an absorption-dominated shielding of electromagnetic waves.

Electrical and Dielectric Properties of Polymer-Metal Hybrid Nanocomposites - A Short Review

Polymer-metal hybrid nanocomposites have garnered significant attention in recent years due to their exceptional electrical and dielectric properties, which find applications in a wide range of industries, including electronics, energy storage, and advanced materials. This review article provides a comprehensive overview of the current state-of-the-art in the field of polymer-metal hybrid nanocomposites, with a particular focus on their electrical and dielectric properties. The first section of the review delves into the synthesis and fabrication techniques employed to create these nanocomposites, highlighting the importance of controlling the dispersion and distribution of metal nanoparticles within the polymer matrix. Various approaches, such as in-situ polymerization, melt mixing, and electrospinning, are discussed in detail, along with their respective advantages and limitations.The subsequent sections explore the influence of metal nanoparticles on the electrical conductivity and dielectric constant of the nanocomposites. The role of factors such as nanoparticle size, shape, and concentration in determining these properties is thoroughly examined. Moreover, the impact of metal surface modifications and the choice of polymer matrix on enhancing electrical and dielectric performance are also addressed. In addition to discussing fundamental aspects, this review highlights practical applications of polymer-metal hybrid nanocomposites in the development of high-performance capacitors, sensors, electromagnetic shielding materials, and flexible electronics. The potential for these materials to revolutionize various technological sectors is discussed, emphasizing their role in advancing miniaturization, energy efficiency, and durability. Furthermore, the review outlines current challenges and future prospects in the field, including the need for a deeper understanding of the underlying mechanisms governing electrical and dielectric behavior in these nanocomposites. Emerging trends such as the incorporation of 2D materials and the development of multifunctional hybrid systems are also explored, hinting at exciting avenues for further research and innovation. In conclusion, polymer-metal hybrid nanocomposites offer a promising platform for tailoring electrical and dielectric properties to meet the demands of modern technology. This review serves as a valuable resource for researchers, engineers, and scientists seeking to explore the potential of these materials and drive advancements in the field of electrical and dielectric engineering.

Accelerating multilayer frequency selective surface absorber design by combining equivalent circuit models with machine learning

Designing high-performance electromagnetic functional materials and artificial structures is of great significance for electromagnetic wave modulation applications. Optimizing performance in the high-dimensional parameter space of electromagnetic functional materials has posed a challenging problem. This paper proposes the use of reinforcement and transfer learning methods to facilitate the quick and accurate design of wideband circuit analog absorbers (CAA). A trained reinforcement learning network is utilized to comprehend the relationship between reflectivity performance and changes in impedance parameter. Furthermore, the transfer learning method is applied to accelerate the training process, leading in a 20-fold reduction in the number of simulations. To validate the effectiveness of this approach, a double-layer absorber aiming for reflectivity less than −20 dB at 3–10 GHz is designed, requiring only 50 simulations. This demonstrates that the proposed method provides a flexible strategy for the interactive design of equivalent circuit and electromagnetic structural parameters. Moreover, it presents a novel and efficient solution for microwave absorber design, with potential applications across various microwave design fields.

Experimental investigation on microstructure, hardness and corrosion resistance of an electromagnetic welded titanium-stainless steel dissimilar materials

The electromagnetic welding (EMW), often known as magnetic pulse welding, is a solid-state welding technology that is used to join two different materials using high-velocity impact. In this study an attempt was made to join the Titanium(Ti)- Stainless Steel(SS 304) materials with the help of multi turn disc coil along with the field shaper. A comparative investigation was conducted on the joint’s microstructure, as well as its mechanical and corrosion properties. Inverted optical microscopy (OM) and x-ray diffraction (XRD) were used to do the microstructural characterization of the joint. The micro-Vickers hardness test was used to analyse the material’s mechanical properties. In addition, electrochemical experiments were run on the Ti-SS 304 EMW junction as well as the component materials to establish how resistant they were to corrosion. Using an electrochemical impedance analyzer, the levels of corrosion that were caused by the structures were measured while they were submerged in a solution of nitric acid at room temperature. The microstructural pictures revealed a wave-like pattern at the material’s interface, which is evidence of strong adhesion between the components. The micro vickers hardness of the joints was within the permitted range, as was the corrosion rate.

Graphite-enhanced foam cement-based materials: Mechanical properties, pore structure and electromagnetic wave absorption performance

To reduce the environmental pollution caused by electromagnetic waves (EMW), graphite-enhanced foam cement-based electromagnetic wave-absorbing materials were prepared. The effects of hydration products and pore structure on the mechanical strength and microstructure have been investigated. The results show that at a graphite content of 10 wt%, resulting in a reduction in pore size and concentration within 400μm. This led to improved material compactness, resulting in an increase in compressive strength of 32.01 % and 29.13 % for 3-day and 28-day foamed concrete, along with a 35.40 % and 29.27 % increase in flexural strength. For the 10 mm thick foamed concrete, the reflection loss is −24.08 dB with an effective absorption bandwidth of 0.466 GHz (3.762–4.228 GHz). The impedance matching increased by 129 %, moving from 8.3 to 10 mm up range to 6.1–10 mm, while the frequency range increased by 61.35 %, moving from 3.37 to 5 GHz up range to 2.37–5 GHz, compared to the control group.

High-efficiency electromagnetic shielding of three-dimensional laminated Wood/Cu/Ni composites

Construction of ideal dissipation path for layered electromagnetic shielding materials (EMSM) is promising but challenging. Herein, high-efficiency EMSM of three-dimensional hydrophobic wood/Cu/Ni laminated composites have been constructed to achieve laminated composites with high electromagnetic shielding efficiency and low reflection. The electromagnetic gradient structures are obtained via different Cu and Ni deposition times, where the slightly magnetic top Ni coatings serves as electromagnetic (EM) absorption layer and the highly conductive Cu coatings as reflection layer. The hierarchical porous wood structure could extend the EM dissipation path and dissipate EM by multiple reflections. Therefore, the laminated structure exhibits an excellent EM shielding efficiency (average 91.6 dB) at only 0.45 mm thickness between 8.2 GHz and 12.4 GHz in frequency. In addition, the contact angle of laminated composites was 117.8° and the Joule heating was nearly to 0, which broaden their application scenarios in practice. Furthermore, the multilayer Cu/Ni wood-based composites with sandwich-structured can be used as EM shielding gaskets and effectively block wireless power transmission and high frequency EM signal, which shows a prosperous application prospect in defense industry and aerospace.

Metal Single‐Atoms Toward Electromagnetic Wave‐Absorbing Materials: Insights and Perspective

AbstractMetal single‐atoms implanted on nitrogen‐doped carbon matrices (M‐NxCs) can effectively adjust local surface electrons and polarization relaxation through coordination structures to significantly enhance the electromagnetic wave (EMW) absorption properties of the materials. However, the precise construction of the geometric and electronic structures of metal single atoms and the discovery of the structure‐absorption relationship at the atomic level confront a huge challenge. Herein, this work summarizes the latest progress in metal single‐atom engineering of EMW absorbing materials via a comprehensive analysis of M‐NxCs in terms of design principles, modulation strategies, and structure‐performance correlations. Subsequently, it highlights the recent progress of several typical M‐NxCs as the EMW absorbing materials, aiming to achieve a complete understanding of the physical effects and atomic‐level absorption mechanisms. Finally, current key challenge and future directions of M‐NxCs are presented by focusing on the electromagnetic functional materials. This work provides new insights for the development of atomically dispersed absorbing materials for efficient electromagnetic response functionalities.

Dual-Step Redox Engineering of 2D CoNi-Alloy Embedded B, N-Doped Carbon Layers Toward Tunable Electromagnetic Wave Absorption and Light-Weight Infrared Stealth Heat Insulation Devices.

2D layered metallic graphite composites are promising electromagnetic wave absorption materials (EWAMs) for their combined properties of abundant interlayer free spaces, rich metallic polarized sites, and high conductivity, but the controllable synthesis remains rather challenging. Herein, a dual-step redox engineering strategy is developed by employing cobalt boron imidazolate framework (Co-BIF) to construct 2D CoNi-alloy embedded B, N-doped carbon layers (2D-CNC) as a promising EWAM. In the first step, a chemical etching oxidation process on Co-BIF is used to obtain an optimized 2D-CoNi-layered double hydroxide (2D-CoNi-LDH) intermediate and in the second, high-temperature calcination reduction is implemented to modify graphitization of the degree of the 2D-CNC. The obtained sample delivers superior reflection loss (RLmin) of -60.1dB and wide effective absorption bandwidth (EAB) of 6.24GHz. The synergy mechanisms of interfacial/dipole polarization and magnetic coupling are in-depth evidenced by the hologram and Lorentz electron microscopy, revealing its significant contribution on multireflection and impedance matching. Further theoretical evaluation by COMSOL simulation in different fields based on the dynamic loss process toward the test ring reveals the in situ EW attenuation process. This work presents a strategy to develop multifunctional light-weight infrared stealthy aerogel with superior pressure-resistant, anti-corrosion, and heat-insulating properties for future applications.

Controlling silver deposition morphology on aluminum surfaces: Surfactant modify anisotropy of aluminum surface energy

Faced with the challenge of uncontrollable Ag layer deposition morphology during the preparation of silver-coated aluminum particles (Al/Ag). A simple and nontoxic method involving the introduction of surfactants (PEG, PVP, and gelatin (GEL)) to alter the anisotropy of Al surface energy was proposed to achieve control over Ag deposition morphology. Theoretical calculations indicate that PEG undergoes physisorption to Al, while PVP and GEL can alter the surface energy of specific crystal planes by selectively binding to different crystal facets. This action alters the growth habit of Ag on the Al surface and modulates the Ag deposition behavior, these conclusions align with experimental results. Compared with PEG and PVP, the incorporation of GEL was beneficial for the formation of a conformal Ag layer. This can be attributed to GEL preferentially passivating the highest crystal plane Al (110) surface, forming a buffer layer at the solid-liquid interface, leveling out the Ag deposition rate on various crystal planes, and also effectively inhibiting side reactions, in addition to enhancing the wettability of reaction solution. The Al/Ag particle exhibits excellent electrical conductivity (1.03 × 10−6 Ω·cm) and electromagnetic absorption (−32.5 dB, 1.62 GHz), it is suitable for use as a highly conductive electromagnetic shielding material.

Flexible, superhydrophobic, and self-cleaning rGO/LDH/PPy-modified fabric for full X-band electromagnetic wave absorption

High-performance flexible microwave absorbing textiles are the subject of a research boom due to the growing need for flexible wearable electronic gadgets that can withstand electromagnetic wave pollution and operate in challenging situations. Herein, we combine the two techniques of thermal reduction and in-situ growth to produce a reduced graphene oxide/FeCo-layered double hydroxide/polypyrrole (rGO/LDH/PPy) coated fabric with good superhydrophobic qualities and high electromagnetic wave absorption (EWA) performance. rGO/LDH and PPy work together to generate a multidimensional heterostructure, which offers the coated fabric a high electromagnetic loss capacity. The coating design uses a fluffy and complicated aramid fabric as the skeleton. The impedance gradient may be created to modify the fabric's ability to absorb electromagnetic waves by varying the concentration of Py. Full coverage of the X-band can be achieved by the coated fabric, which has an RLmin of −45.0 dB and a thickness of 3.5 mm. The layered rough structure generated by PPy, FeCo-LDH, and rGO in conjunction with the low surface energy material SN-67 results in an exceptional superhydrophobic property with a WCA of 156.9° for the coated fabric. Furthermore, this rGO/LDH/PPy coated fabric is robust and does not lose its superhydrophobicity even after repeated tape stripping, extended chemical exposure, and high and low temperature conditions. This work indicates potential application value for flexible electromagnetic wave-absorbing materials that maintain high efficiency in challenging situations, and it offers a solid foundation for the design of multifunctional EWA materials based on textiles.

3D-Networks Based Polymer Composites for Multifunctional Thermal Management and Electromagnetic Protection: A Mini Review

3D-Networks Based Polymer Composites for Multifunctional Thermal Management and Electromagnetic Protection: A Mini Review

Pengembangan Media Praktikum Percobaan Hukum Oersted Pada Materi Elektromagnetik

This research focuses on developing practical media in the form of practical tools for Oersted's Law on electromagnetic materials. The reason for this research is taken from a problem that usually occurs in schools where the facilities and infrastructure are inadequate for carrying out practicums so that it is difficult to explain the concept of electronic materials. This research aims to develop a set of learning media in the form of practical tools about Oersted's Law in electromagnetic material, more precisely material about electromagnetic induction. With this media, students are expected to more easily understand the concept of electromagnetic induction. The practicum media development stages include (1) data collection (2) product design (3) design verification (4) design modification (5) product testing (6) product modification (7) prototype production (8) mass production. The tools and materials used are a compass, battery, wire, nails and wooden planks which are arranged and combined

Enhancing microwave absorption via ion exchange-regulated metal elemental-alloy transition behavior

Metal-organic frameworks (MOFs) are considered as suitable candidates for excellent microwave absorption (MA) materials. However, the influence of the transition behavior from metal to alloy dominated by the metal ion ratio and the accompanying multi-phase coexistence model on the MA mechanism is unclear. This study successfully prepared a series of porous electromagnetic composite materials through ion-exchange in-situ pyrolysis synergistic strategy. The results indicate that the modulation of the Fe/Co ion ratio can easily manipulate the phase transition from Co metal to FeCo alloy-cobalt ferrite and the crystal defects within. The state of metal/alloy coexistence obtained at a low ion exchange degree has the highest concentration of vacancies, which is conducive to wideband absorption (6.03 GHz) and efficient loss (−67.44 dB) of MA performance. In contrast, the MA performance of samples at medium/high ion exchange degrees is not ideal. In addition, the application prospects of this material were demonstrated by simulating the actual absorption situation using radar cross-section. In summary, this work reveals the intrinsic relationship between the phase evolution behavior determined by the ion exchange degree in MOF derivatives and the electromagnetic performance, as well as the MA mechanism, providing a new reference for the preparation and design of outstanding MA materials.

Enhanced electromagnetic wave absorption of magnetite-spinach derived carbon composite

The high density, high cost, and environmental pollution hinder the application of iron-based electromagnetic wave-absorbing materials. Although bio-carbon is a green and lightweight dielectric wave-absorbing material, the wave-absorbing performance of bio-carbon is still limited. This work successfully combined magnetite Fe3O4 with porous carbon derived from spinach stem using hydrothermal and calcination methods. This process optimizes the matching of the dielectric constant and magnetoconductivity of the as prepared composite material, resulting in a significant improvement in electromagnetic microwave absorption capacity. XRD, SEM, TEM, XPS, VSM and EMW absorption network analyzer are used to detect and characterize the samples. The composite material shows a excellent minimum reflection loss value of −48.81 dB and an efficacious absorption bandwidth of 4.73 GHz at the optimal raw material ratio. The tests also show the porous structure of the sample with the coercivity and saturation magnetization of 29.36 Oe and 10.75 emu/g, respectively. The test results indicate that the excellent electromagnetic wave absorption is due to the synergistic effect of multiple reflection, Debye relaxation, and interfacial polarization. This Fe3O4-bio-carbon composite is cheap and simple to prepare, and it also has excellent wave absorption performance. Therefore, it shows great application potential in civilian and military electromagnetic wave absorption fields.

Polypyrrole/Fe3O4 nanocomposites anchored on graphene toward efficient electromagnetic wave absorption performance

The ternary nanocomposites of polypyrrole/Fe3O4/graphene (PPy/Fe3O4/RGO) have been prepared via a two-step method. PPy/Fe3O4 composites have been initially anchored on GO surface by chemical one-step method following by reducing GO. The electromagnetic wave absorption (EMWA) performance of composites can be tuned by adjusting the amount of pyrrole monomers. The maximum reflection loss of the PPy/Fe3O4/RGO-0.5 (pyrrole:0.5 mL) composite is up to −66.0 dB at 14.88 GHz and the absorption bandwidths exceeding −10 dB were 5.76 GHz with absorber thickness of 2.5 mm. The investigation of the electromagnetic absorb-ability reveals that PPy/Fe3O4/RGO exhibits enhanced electromagnetic absorption properties compared to Fe3O4/RGO, which is mainly ascribed to the improved impedance matching, the enhanced interfacial effects and geometric effect. Furthermore, this strategy expands the scope of the electromagnetic wave absorption materials. It confirms that modification of graphene with PPy and Fe3O4 makes the ternary nanocomposites have a promising future in electromagnetic wave absorption materials.

Multiple birds with one stone: A new type of PPy/Fe3O4/rGO multifunctional composite fabric for wave absorption, UV resistance, anti-static and thermal insulation

To solve the problem of electromagnetic radiation pollution, it is especially important to develop electromagnetic wave-absorbing materials with excellent performance. The preparation of composite multifunctional textile materials with excellent wave-absorbing properties is one of the research hotspots for practical personal protection applications. In this work, PPy/Fe3O4/rGO polyester/cotton composite fabrics were prepared by impregnation, chemical reduction, chemical co-precipitation and in situ polymerization. When the thickness is 0.97 mm, the minimum reflection loss (RLmin) of PPy/Fe3O4/rGO polyester/cotton composite fabric is −12.12 dB, and the effective absorption bandwidth (EAB) is 4.7 GHz, which is excellent in wave absorption. Meanwhile, the PPy/Fe3O4/rGO polyester/cotton composite fabrics have excellent UV resistance (UV transmittance ratio of UVA and UVB bands as low as 0.02 %, UPF value of 100+), antistatic properties (static voltage half-life of 0.2 s), and excellent thermal management properties (thermal conductivity as low as 0.05796 W/(m·K)), and so on. The PPy/Fe3O4/rGO polyester/cotton composite fabrics prepared in this study are suitable for a variety of application scenarios, such as individual electromagnetic protection, individual protection in extremely cold environments, and individual heating physiotherapy, which is of great reference significance for the research of wearable individual protective textile materials.

Optimization of three dimensional rGO@MWCNTs/Fe3O4-PVA composite film through regulated structure for convenient and replaceable electromagnetic wave absorption material

Optimizing the composition and structure of polymers and carbon nanomaterials to obtain composite films with excellent mechanical and electromagnetic wave (EMW) properties is an excellent solution for exploring EMW absorbing materials. In this work, a flexible composite film with a regular three-dimensional network structure was designed and prepared. The modified rGO@MWCNTs/Fe3O4-PVA composite nanofilm with optimized composition and structure has a multi-component heterogeneous interface, three-dimensional network structure. The composite film has high EMW absorption performance, excellent flexibility, mechanical strength and stability, and can be used in a wide range of application scenarios. At a thickness of 2.8 mm, the effective absorption bandwidth (fE) reaches 3.72 GHz, the minimum reflection loss (RLmin) is -48.99 dB, and the tensile stress reaches 32 MPa. This work realizes the regulation of the mechanical properties and EMW absorbing properties of the composite film, and provides an efficient and stable flexible composite EMW absorbing material.