scholarly journals A Flexible Sandwich Structure Carbon Fiber Cloth with Resin Coating Composite Improves Electromagnetic Wave Absorption Performance at Low Frequency

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 233
Author(s):  
Yuanjun Liu ◽  
Qianqian Lu ◽  
Jing Wang ◽  
Xiaoming Zhao
Keyword(s):  
Electromagnetic Wave ◽  
Carbon Fiber ◽  
Reflection Loss ◽  
High Speed ◽  
Control Variable ◽  
Low Frequency ◽  
Interfacial Polarization ◽  
Multiple Reflections ◽  
Carbon Fiber Cloth ◽  
Minimum Reflection Loss

In order to improve the electromagnetic wave absorbing performance of carbon fiber cloth at low frequency and reduce the secondary pollution caused by the shielding mechanism, a flexible sandwich composite was designed by a physical mixing coating process. This was composed of a graphene layer that absorbed waves, a carbon fiber cloth layer that reflected waves, and a graphite layer that absorbed transmitted waves. The influence of the content of graphene was studied by a control variable method on the electromatic and mechanical properties. The structures of defect polarization relaxation and dipole polarization relaxation of graphene, the interfacial polarization and electron polarization of graphite, the conductive network formed in the carbon fiber cloth, and the interfacial polarization of each part, combined together to improve the impedance matching and wave multiple reflections of the material. The study found that the sample with 40% graphene had the most outstanding absorbing performance. The minimum reflection loss value was −18.62 dB, while the frequency was 2.15 GHz and the minimum reflection loss value compared to the sample with no graphene increased 76%. The composites can be mainly applied in the field of flexible electromagnetic protection, such as the preparation of stealth tent, protective covers of electronic boxes, helmet materials for high-speed train drivers, etc.

scholarly journals Spawns Structure of Rod-Like ZnO Wrapped in Cellulose Nanofibers for Electromagnetic Wave Absorption

2017 ◽  
Vol 2017 ◽  
pp. 1-6
Author(s):  
Bitao Fan ◽  
Qiufang Yao ◽  
Chao Wang ◽  
Ye Xiong ◽  
Qingfeng Sun ◽  
...  
Keyword(s):  
Electromagnetic Wave ◽  
Reflection Loss ◽  
Cellulose Nanofibers ◽  
Absorption Properties ◽  
Composite Aerogel ◽  
Electromagnetic Wave Absorption ◽  
Wave Absorption ◽  
One Step ◽  
Absorption Performance ◽  
Minimum Reflection Loss

Spawns structure of rod-like ZnO wrapped in the cellulose nanofibers was successfully fabricated through a facile one-step hydrothermal method, and their electromagnetic wave absorption properties were investigated. The structure and properties of the composite aerogel were characterized. The enlarged morphology images showed that the as-prepared cellulose nanofiber/ZnO samples were spawns structure of rod-like ZnO wrapped in the cellulose nanofibers. The composite aerogel in a wax matrix exhibited excellent electromagnetic wave absorption performance over 2–18 GHz. The widest absorption bandwidth of 30 wt% contained with reflection loss values less than −10 dB was up to 12 GHz (6–18 GHz) at the thickness of 5.5 mm and the minimum reflection loss value reached −26.32 dB at 15.2 GHz when the thickness of the absorber was 3 mm.

Investigation of the electromagnetic absorption properties of Ni@TiO2 and Ni@SiO2 composite microspheres with core–shell structure

2015 ◽  
Vol 17 (4) ◽  
pp. 2531-2539 ◽  
Author(s):  
Biao Zhao ◽  
Gang Shao ◽  
Bingbing Fan ◽  
Wanyu Zhao ◽  
Rui Zhang
Keyword(s):  
Electromagnetic Wave ◽  
Reflection Loss ◽  
Core Shell ◽  
Absorption Properties ◽  
Electromagnetic Wave Absorption ◽  
The Core ◽  
Composite Microspheres ◽  
Electromagnetic Absorption ◽  
Core Shell Structure ◽  
Minimum Reflection Loss

The core–shell Ni–SiO2 composite exhibits the best electromagnetic wave absorption in the GHz range with a minimum reflection loss of −40.0 dB, which is superior to those of Ni–TiO2 and Ni microspheres.

Microwave Absorbing Property of Thin Coating in the Broadband Low-Frequency Range

2018 ◽  
Vol 916 ◽  
pp. 33-37
Author(s):  
Le Chen ◽  
Zhao Zhan Gu ◽  
Ming Xue Zhang
Keyword(s):  
Reflection Loss ◽  
Complex Permittivity ◽  
Carbonyl Iron ◽  
Low Frequency ◽  
Complex Permeability ◽  
Frequency Range ◽  
Microwave Absorbing ◽  
Absorbing Property ◽  
Lower Frequency Region ◽  
Minimum Reflection Loss

Coatings with flake carbonyl-iron powder as absorber and polyurethane resin as matrix were prepared. The complex permittivity, complex permeability and microwave-absorbing properties were investigated in the frequency range of 2–18 GHz. Both the complex permittivity and permeability of the flaky carbonyl-iron were increased compared to the spherical powders. The minimum reflection loss decreased and the matching frequency shifted to the lower frequency region with increase in the coating thickness. The band width can reach nearly 16GHz as the RL was below than-4 dB with thickness only 1.4 mm. The minimum reflection loss value of-14.5 dB was obtained at 3.56 GHz for the 1.6mm coatings with 89 wt% carbonyl-iron powders. These results showed that the coatings were favorable for the broadband low-frequency microwave absorption with a small thickness.

scholarly journals Porous SiC/melamine-derived carbon foam frameworks with excellent electromagnetic wave absorbing capacity

2019 ◽  
Vol 8 (4) ◽  
pp. 479-488 ◽  
Author(s):  
Xinli Ye ◽  
Zhaofeng Chen ◽  
Sufen Ai ◽  
Bin Hou ◽  
Junxiong Zhang ◽  
...  
Keyword(s):  
Electromagnetic Wave ◽  
Reflection Loss ◽  
Impedance Matching ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Carbon Foam ◽  
Wave Absorption ◽  
Potential Applications ◽  
Novel Strategy ◽  
Minimum Reflection Loss

Abstract Porous three-dimensional SiC/melamine-derived carbon foam (3D-SiC/MDCF) composite with an original open pore structure was fabricated by the heat treatment of the commercial melamine foam (MF), carbonization of the stable MF, and chemical vapor deposition of the ultra-thin SiC coating. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to detect the microstructure and morphology of the as-prepared composites. The results indicated that the 3D-SiC/MDCF composites with the coating structure were prepared successfully. The obtained minimum reflection loss was -29.50 dB when the frequency and absorption thickness were 11.36 GHz and 1.75 mm, respectively. Further, a novel strategy was put forward to state that the best microwave absorption property with a thin thickness of 1.65 mm was gained, where the minimum reflection loss was -24.51 dB and the frequency bandwidth was 3.08 GHz. The excellent electromagnetic wave absorption ability resulted from the specific cladding structure, which could change the raw dielectric property to acquire excellent impedance matching. This present work had a certain extend reference meaning for the potential applications of the lightweight wave absorption materials with target functionalities.

Efficient microwave traps with markedly enhanced interfacial polarization and impedance matching enabled by dual-shelled, dual-cavity magnetic@dielectric hollow nanospheres

2020 ◽  
Vol 8 (46) ◽  
pp. 16489-16497
Author(s):  
Jiasong Hua ◽  
Wenjun Ma ◽  
Xiaoyun Liu ◽  
Qixin Zhuang ◽  
Zeyang Wu ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Reflection Loss ◽  
Impedance Matching ◽  
Interfacial Polarization ◽  
Hollow Nanospheres ◽  
Absorption Performance ◽  
Microwave Absorption Performance ◽  
Magnetic Dielectric ◽  
Minimum Reflection Loss

Dual-shelled, dual-cavity Fe3O4@TiO2 hollow nanospheres exhibit an outstanding microwave absorption performance with a minimum reflection loss of −60.17 dB.

scholarly journals Non-Magnetic Bimetallic MOF-Derived Porous Carbon-Wrapped TiO2/ZrTiO4 Composites for Efficient Electromagnetic Wave Absorption

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Jing Qiao ◽  
Xue Zhang ◽  
Chang Liu ◽  
Longfei Lyu ◽  
Yunfei Yang ◽  
...  
Keyword(s):  
Electromagnetic Wave ◽  
Porous Carbon ◽  
Metal Organic Framework ◽  
Interfacial Polarization ◽  
Communication Technologies ◽  
List Type ◽  
Electromagnetic Wave Absorption ◽  
Wave Absorption ◽  
Metal Organic ◽  
Minimum Reflection Loss

Highlights Non-magnetic bimetallic MOF-derived porous carbon-wrapped TiO2/ZrTiO4 composites are firstly used for efficient electromagnetic wave absorption. The electromagnetic wave absorption mechanisms including enhanced interfacial polarization and essential conductivity are intensively discussed. Abstract Modern communication technologies put forward higher requirements for electromagnetic wave (EMW) absorption materials. Metal–organic framework (MOF) derivatives have been widely concerned with its diverse advantages. To break the mindset of magnetic-derivative design, and make up the shortage of monometallic non-magnetic derivatives, we first try non-magnetic bimetallic MOFs derivatives to achieve efficient EMW absorption. The porous carbon-wrapped TiO2/ZrTiO4 composites derived from PCN-415 (TiZr-MOFs) are qualified with a minimum reflection loss of − 67.8 dB (2.16 mm, 13.0 GHz), and a maximum effective absorption bandwidth of 5.9 GHz (2.70 mm). Through in-depth discussions, the synergy of enhanced interfacial polarization and other attenuation mechanisms in the composites is revealed. Therefore, this work confirms the huge potentials of non-magnetic bimetallic MOFs derivatives in EMW absorption applications.

Attenuation of low-frequency electromagnetic wave in the thin sheath enveloping a high-speed vehicle upon re-entry

2017 ◽  
Vol 121 (7) ◽  
pp. 074903 ◽  
Author(s):  
DongLin Liu ◽  
XiaoPing Li ◽  
YanMing Liu ◽  
Kai Xie ◽  
BoWen Bai
Keyword(s):  
Electromagnetic Wave ◽  
High Speed ◽  
Low Frequency ◽  
High Speed Vehicle

scholarly journals High Absorption Electromagnetic Wave Properties of Composite CoFeO3 Synthesized by Simple Mechanical Alloying

2021 ◽  
Author(s):  
Heryanto Heryanto ◽  
Dahlang Tahir
Keyword(s):  
Electromagnetic Wave ◽  
Mechanical Alloying ◽  
Human Health ◽  
High Performance ◽  
Magnetic Domain ◽  
Interfacial Polarization ◽  
Multiple Reflections ◽  
Microwave Absorbing Materials ◽  
Transition Metal Atoms ◽  
Domain Loss

Abstract Electronic equipment demand is strongly correlated to the electromagnetic wave interference (EMI), which causes severe effects on human health. Microwave absorbing materials (MAMs) are one method to protect human health from EMI. Cobalt nanoparticles show high performance as MAMs. Here, we have synthesized CoFeO3 by simple mechanical alloying for increased multiple reflections, interfacial polarization, magnetic domain loss, electron spin loss, internal resonance, hoping electron, conductive loss, and multiple scattering for improved absorption of EMI waves. We determined the electronic properties from the Quantum Espresso (QE) and corresponding results are discussed. The metallic character comes from the d-state of transition metal atoms Fe (II) and Co which are sufficiently large in magnitude in the Fermi level of band structure and density of state (DOS) distribution. Crystallite size in the range of 13.6 to 18.7 nm with surface morphology shows irregular shapes of the particles. For CoFeO3 as MAMs, we found that the reflection loss (RL) is -55 dB (lower than the previous reported -43.2 dB) at 10-11 GHz for a thickness of 8 mm, indicating that this study shows high potential of CoFeO3 as an alternative composite for MAMs applications.

scholarly journals Enhanced Electromagnetic Wave Absorption Properties of Ultrathin MnO2 Nanosheet-Decorated Spherical Flower-Shaped Carbonyl Iron Powder

Molecules ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 135
Author(s):  
Zhengwei Qu ◽  
Yi Wang ◽  
Pingan Yang ◽  
Wei Zheng ◽  
Nan Li ◽  
...  
Keyword(s):  
Electromagnetic Wave ◽  
Iron Powder ◽  
Oxidation Resistance ◽  
Reflection Loss ◽  
Carbonyl Iron ◽  
Absorption Properties ◽  
Absorption Bandwidth ◽  
Electromagnetic Wave Absorption ◽  
Wave Absorption ◽  
Minimum Reflection Loss

In this work, spherical flower-shaped composite carbonyl iron powder@MnO2 (CIP@MnO2) with CIP as the core and ultrathin MnO2 nanosheets as the shell was successfully prepared by a simple redox reaction to improve oxidation resistance and electromagnetic wave absorption properties. The microwave-absorbing properties of CIP@MnO2 composites with different filling ratios (mass fractions of 20%, 40%, and 60% after mixing with paraffin) were tested and analyzed. The experimental results show that compared with pure CIP, the CIP@MnO2 composites have smaller minimum reflection loss and a wider effective absorption bandwidth than CIP (RL < −20 dB). The sample filled with 40 wt% has the best comprehensive performance, the minimum reflection loss is −63.87 dB at 6.32 GHz, and the effective absorption bandwidth (RL < −20 dB) reaches 7.28 GHz in the range of 5.92 GHz–9.28 GHz and 11.2 GHz–15.12 GHz, which covers most C and X bands. Such excellent microwave absorption performance of the spherical flower-like CIP@MnO2 composites is attributed to the combined effect of multiple beneficial components and the electromagnetic attenuation ability generated by the special spherical flower-like structure. Furthermore, this spherical flower-like core–shell shape aids in the creation of discontinuous networks, which improve microwave incidence dispersion, polarize more interfacial charges, and allow electromagnetic wave absorption. In theory, this research could lead to a simple and efficient process for producing spherical flower-shaped CIP@MnO2 composites with high absorption, a wide band, and oxidation resistance for a wide range of applications.

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