Effect of Structure Modification on the Microwave Absorbing Performance of Carbon Foams

Carbon foams were prepared by a polymer sponge replication process and their microwave absorbing properties were investigated. The electric conductivity of carbon foam has a direct effect on its microwave absorbing property, as the carbon foam with a medium electric conductivity of 0.46S/m has got a relatively excellent microwave absorbing property and demonstrated a characteristic of broadband absorption. Some structure modification has been made on carbon foams to fruther imrove their microwave absorbing performance. The result shows that making slots, especially gradient slots on the surface of carbon foams can greatly improve their microwave absorbing properties, while the reflection coefficients for a three-layered carbon foam structure exceeds -10dB with the combination effect of multilayer structure design and parameters gradient variatioin in the whole frequency range of 2.6-18GHz, which is usually to be considered as the practical application standard for microwave absorbing materials.

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Novel Radar Absorbing Materials with Broad Absorbing Band: Carbon Foams

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.26-28.246 ◽

2010 ◽

Vol 26-28 ◽

pp. 246-249 ◽

Cited By ~ 3

Author(s):

Zhi Gang Fang ◽

Chun Fang

Keyword(s):

Electric Conductivity ◽

Carbon Foam ◽

Impedance Match ◽

Frequency Range ◽

Microwave Absorbing Properties ◽

Replication Method ◽

Carbon Foams ◽

Electromagnetic Behavior ◽

Measured Frequency Range ◽

Microwave Absorbing

Carbon foams were prepared by a polymer sponge replication method and their microwave absorbing properties were investigated in this paper. It was found that the electric conductivity of carbon foams increases quickly with the improvement of carbonization temperatures. Moreover, the electric conductivity of carbon foams strongly affects their microwave absorbing performances. As the electric conductivity increases from 0.02 S/m to 1.03 S/m, the dominant electromagnetic behavior of carbon foams changes from transmission to reflection with regard to the incident electromagnetic wave. The best microwave absorbing performance was achieved for the carbon foam with an electric conductivity of 0.46S/m when other parameters are fixed at constants, and absorbing values for the carbon foam exceeds 7dB almost in the whole measured frequency range of 4-15GHz, while the frequencies range for absorbing values exceeding 8dB are about 7 GHz, demonstrating a characteristic of broad absorbing bandwidth. It is to be noted that the absorbing characteristic for the carbon foam with an electric conductivity of 0.46S/m is obtained without any impedance match design, which indicates that carbon foams have the possibility to be applied as broad absorbing bandwidth RAMs.

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The Preparation of FeCo/ZnO Composites and Enhancement of Microwave Absorbing Property by Two-Step Method

Materials ◽

10.3390/ma12193259 ◽

2019 ◽

Vol 12 (19) ◽

pp. 3259

Author(s):

Ka Gao ◽

Junliang Zhao ◽

Zhongyi Bai ◽

Wenzheng Song ◽

Rui Zhang

Keyword(s):

Single Phase ◽

Effective Bandwidth ◽

Frequency Range ◽

Step Method ◽

Absorption Properties ◽

Composite Surface ◽

Microwave Absorbing Properties ◽

Microwave Absorbing Property ◽

Microwave Absorbing ◽

Absorbing Property

In this paper, the flower-like FeCo/ZnO composites were successfully firstly prepared by a two-step method, and their microstructures and microwave absorbing properties were characterized. The results show that with an increase of temperature, the content of ZnO loaded on a FeCo/ZnO composite surface was increased. The optimal reflection loss (RL) value can be reached around −53.81 dB at 9.8 GHz, which is obviously superior to results of previous studies and reports, and its effective bandwidth (RL < −10 dB) is 3.8 GHz in the frequency range of 8.7–11.8 GHz with a matching thickness of 1.9 mm. We considered that a large number of lamellar and rod-like ZnO loaded on nano-FeCo single-phase solid solution by two-step method can significantly improve the electromagnetic wave absorption properties.

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Carbon Foams with Special Electromagnetic Loss Characteristics and Broad Absorbing Band

MRS Proceedings ◽

10.1557/proc-1247-c04-08 ◽

2010 ◽

Vol 1247 ◽

Author(s):

Zhigang Fang ◽

Chun Fang

Keyword(s):

Electric Conductivity ◽

Magnetic Loss ◽

Carbon Foam ◽

Impedance Match ◽

Electromagnetic Properties ◽

Replication Method ◽

Carbon Foams ◽

Electromagnetic Loss ◽

Great Possibility ◽

Absorbing Property

AbstractCarbon foams with a reticulated macrostructure were prepared by a polymer sponge replication method. The electromagnetic parameters of carbon foams with variable electric conductivity were measured at a frequency of 2450MHz. Compared with the same composition pulverized powders, carbon foams have relatively lower dielectric constant but much larger dielectric loss, and more remarkably, carbon foams have magnetic loss. The microwave absorbing property measurement of carbon foams was also conducted. A relatively broad absorbing band performance has been got for carbon foams, and the absorbing values exceeds 7dB almost in the whole measured frequency range of 4-15GHz, while the frequencies range for absorbing values exceeding 8dB are about 7 GHz for the carbon foam with an electric conductivity of 0.46S/m. It is worthy that the broad absorbing band feature of the carbon foam is obtained without any impedance match design, which indicates carbon foams have a great possibility of being applied as RAMs. The special electromagnetic loss characteristics and prominent radar absorbing properties about carbon foams indicate macrostructure modification is possibly a new and effective way to modulate the electromagnetic properties of RAMs besides the traditional composition variation.

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Preparation and microwave-absorbing property of BaFe12O19 nanoparticles and BaFe12O19/Fe3C/CNTs composites

RSC Advances ◽

10.1039/c5ra16310b ◽

2015 ◽

Vol 5 (111) ◽

pp. 91665-91669 ◽

Cited By ~ 29

Author(s):

Liangjun Yin ◽

Tong Chen ◽

Shiyu Liu ◽

Yuqi Gao ◽

Biao Wu ◽

...

Keyword(s):

Chemical Vapor Deposition ◽

Great Improvement ◽

Vapor Deposition ◽

Chemical Vapor ◽

Deposition Process ◽

Chemical Vapor Deposition Process ◽

Microwave Absorbing Properties ◽

Microwave Absorbing Property ◽

Microwave Absorbing ◽

Absorbing Property

A novel kind of BaFe12O19/Fe3C/CNTs composite was developed by the acetylene chemical vapor deposition process. The composites perform great improvement in the microwave absorbing properties compared with pure BaFe12O19 ferrite in 2–18 GHz range.

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