Controllable synthesis of multi-shelled SiO2@C@NiCo2O4 yolk-shell composites for enhancing microwave absorbing properties

2021 ◽  
Author(s):  
Shanshan Wang ◽  
Huanhuan Zhu ◽  
Qingze Jiao ◽  
Xiaoguang Jiao ◽  
Caihong Feng ◽  
...  
Keyword(s):  
Electromagnetic Radiation ◽  
Controllable Synthesis ◽  
Microwave Absorbing Properties ◽  
Strong Wave ◽  
Absorbing Materials ◽  
Microwave Absorbing

With the increasingly serious pollution of electromagnetic radiation, the task of developing light and strong wave-absorbing materials is becoming more and more urgent. In this study, a novel SiO2@ C@...

Effect of High-Energy Ball Milling on Microstructure and Microwave Absorbing Properties of NdFe Material

2011 ◽  
Vol 311-313 ◽  
pp. 1281-1285 ◽  
Author(s):  
Pei Hao Lin ◽  
Lei Wang ◽  
Shun Kang Pan ◽  
Hua Mei Wan
Keyword(s):  
Ball Milling ◽  
Particle Morphology ◽  
High Energy ◽  
High Energy Ball Milling ◽  
X Ray ◽  
Microwave Absorbing Properties ◽  
Absorbing Materials ◽  
Milling Method ◽  
Energy Ball ◽  
Microwave Absorbing

The NdFe magnetic absorbing materials were prepared by rapid solidification and high-energy ball milling method. The effect of high-energy ball milling on particle morphology, organizational structure and microwave absorbing properties of NdFe magnetic absorbing materials were analyzed with the aid of X-ray diffractometer, scanning electron microscope and vector network analysis. The results show that the Nd2Fe17 and α-Fe phase are refined, the particles become smaller and thinner; the span-ratio of the particles increases along with time during the process of high-energy ball milling; and meanwhile, the frequency of absorbing peak reduces. The absorbing bandwidth broadens as the increase of the time of ball milling, except that of 48h.The minimum reflectance of the powder decreases from -22dB to - 44dB under the circumstances that the time of high energy ball milling reaches 48h and the thickness of the microwave absorbing coating is 1.5mm. But it rebounds to about - 6dB when the time of ball milling reaches 72h.

Design, Preparation and Microwave-Absorbing Properties of Sandwich-Structure Radar-Absorbing Materials Reinforced by Glass and SiC Fibres

2014 ◽  
Vol 788 ◽  
pp. 573-579 ◽  
Author(s):  
Hai Tao Liu ◽  
Hai Feng Cheng
Keyword(s):  
Electrical Resistivity ◽  
Sandwich Structure ◽  
Microwave Absorbing Properties ◽  
Dielectric Layers ◽  
Impedance Characteristics ◽  
Absorbing Materials ◽  
Resistive Sheet ◽  
Microwave Absorbing ◽  
Smith Chart ◽  
Good Agreement

In order to broaden the absorbing bandwidth of radar-absorbing materials (RAMs), a type of sandwich-structure RAMs (SSRAMs) derived from a Salisbury absorber and comprising two dielectric layers and one resistive sheet was investigated. In this paper, the impedance characteristics of the SSRAMs were analysed and the mechanisms of broadening microwave-absorbing bandwidth were interpreted using a Smith chart. In order to realise the study’s SSRAMs, plain-woven glass fibre fabric and silicon carbide (SiC) fibre fabric with low electrical resistivity were employed as reinforcements of the dielectric layers and lossy layer, respectively. The microwave-absorbing properties of the SSRAMs were measured and compared with simulated results. The results showed that the experimental and simulated results were in good agreement, that the SSRAMs had better wideband microwave-absorbing properties and that the microwave-absorbing bandwidth at reflectivity below −10 dB can reach 11.6 GHz.

Controllable synthesis and enhanced microwave absorbing properties of Fe3O4/NiFe2O4/Ni heterostructure porous rods

2016 ◽  
Vol 387 ◽  
pp. 190-201 ◽  
Author(s):  
Yana Li ◽  
Tong Wu ◽  
Keying Jin ◽  
Yao Qian ◽  
Naxin Qian ◽  
...  
Keyword(s):  
Controllable Synthesis ◽  
Microwave Absorbing Properties ◽  
Microwave Absorbing

Microwave Absorbing Properties of MnAlFe Magnetic Powder

2016 ◽  
Vol 852 ◽  
pp. 3-8 ◽  
Author(s):  
Ye Liu ◽  
Shun Kang Pan ◽  
Pei Hao Lin ◽  
Xing Liu ◽  
Li Chun Cheng
Keyword(s):  
Electromagnetic Interference ◽  
Permanent Magnets ◽  
High Energy ◽  
Absorption Peak ◽  
Absorption Properties ◽  
Microwave Absorbing Properties ◽  
Stealth Technology ◽  
Microwave Absorbing Materials ◽  
Absorbing Materials ◽  
Microwave Absorbing

MnAlFe alloy was prepared by the combined use of smelting, high-energy ball milling and tempering heat treatment process. The phase composition and microwave absorbing properties of MnAlFe alloy were investigated by X-ray diffractometer(XRD) and vector network analyzer. The results show that the powders consist of Al8Mn5 single phase with different Fe content; the dielectric loss and the magnetic loss increases with the addition of Fe, the resonant frequency and absorption peak of ε″ and μ″ moves towardslower frequency region simultaneously. The (Al8Mn5)99Fe exhibits preferably comprehensive microwave absorbing properties in the range of 6-18 GHz. The value of the minimum reflectivity and absorption peak frequency with the coating thickness of 1.5 mm, are -23.1 dB, 15.04 GHz respectively. Owing to the wide applications of electromagnetic waves in the range of 1–4 GHz for mobile phone, local area network, radar systems and so on over the past few decades, the serious problems of the electromagnetic interference and electromagnetic compatibility have become increasingly prominent in recent years. Microwave absorbing materials, which possess special performance for absorbing electromagnetic wave, have been applied in both civil and military fields and play an important role in camouflage technology. In military field, stealth technology to reduce and eliminate the electromagnetic radiation and electromagnetic interference resulting from the broad applications of various kinds of electronic and microwave instruments, stealth technology plays an important strategic role in the wars in future[1-2]. The microwave absorbing materials can be used to reduce radar cross section for military use. For this reason, the microwave absorbing material is vitally important for both civil and military fields[3-7]. In view of this utilization, excellent microwave absorbing materials should exhibit strong microwave absorption properties over a wide frequency range and need to be thin and light in weight. It has an important meaning to the application of magnetic microwave absorbing materials. MnAl alloy can be used as microwave absorbent. It has properties such as light in weight, good thermal stability and corrosion resistance[8-11]. But as permanent magnets, MnAl has shortcomings such as their difficulties of fabrication and high costs that prevent them from being used as permanent magnets. A great value would be brought to either theory or practice through proper treatments as further improvement in properties. In this paper, we will discuss the effects of changing relative content of Fe on absorption properties of Al8Mn5 alloy.

Preparation of Oriented Fe2O3 Film on Glass/Si Substrate by Atmospheric MOCVD

2005 ◽  
Vol 475-479 ◽  
pp. 3749-3752 ◽  
Author(s):  
Jin Cheng ◽  
Yue Zhang
Keyword(s):  
Phase Composition ◽  
Substrate Temperature ◽  
Optimal Conditions ◽  
Si Substrate ◽  
Microwave Absorbing Properties ◽  
Microwave Absorbing Materials ◽  
Absorbing Materials ◽  
Microwave Absorbing ◽  
Fe2o3 Film ◽  
Deposition Conditions

In recent years, much work has been done on microwave absorbing materials, and anisotropy magnetic materials are expected to have excellent microwave absorbing properties. We have prepared well-aligned ZnO whiskers on glass substrate by atmospheric MOCVD. In the present work, Fe2O3 film is deposited by this technique. The phase composition, orientation and morphology of deposited products are studied by XRD and SEM. The effects of the deposition conditions (such as vaporizing temperature, substrate temperature, distance from nozzle to substrate, and carrier gas flux) are investigated. The optimal conditions for the preparation of orientated Fe2O3 film and even well-aligned whisker array are discussed.

Effect of Doping Cerium Oxide on Microwave Absorbing Properties of Polyaniline/Al-Alloy Foams Composite Materials

2014 ◽  
Vol 893 ◽  
pp. 295-298
Author(s):  
Yu Zhang ◽  
Jian Ming Wang ◽  
Tian Guo Zhou
Keyword(s):  
Cerium Oxide ◽  
Rare Earth Oxide ◽  
Al Alloy ◽  
Wave Band ◽  
X Ray ◽  
Microwave Absorbing Properties ◽  
Absorbing Materials ◽  
Microwave Absorbing ◽  
Cross Section Method ◽  
Effect Of Doping

To study the effect of doping cerium oxide on the microwave absorbing properties of Polyaniline /Al-alloy foams, the surface of Al-alloy foams was coated with Polyaniline (denoted by CfP),and doping 1%, 2%,5% (mass percent) cerium oxide (denoted by CfP1,CfP2,CfP5) of Polyaniline respectively. The coated Al-alloy foams were tested according to the Standard GJB 2038-94 Method to test the reflectivity of radar absorbing materials, i.e., the RCS (radar cross-section) method. The morphology and distribution of microwave absorbent were analyzed by scanning electron microscopy (SEM) and X-Ray Diffractomer (XRD).The absorbing properties of each example under different wave band were discussed. The results indicated that in the 12~18GHz and 26.5~40GHz bands the absorbing properties increase with the increase of frequency, and after doping the rare earth oxide, the absorbability of the composite material was enhanced.

Microwave Absorbing Properties of Carbon Fibers Modified with BN/SiC Composite Coatings

2014 ◽  
Vol 29 (10) ◽  
pp. 1093 ◽  
Author(s):  
ZHOU Wei ◽  
XIAO Peng ◽  
LI Yang ◽  
LUO Heng ◽  
HONG Wen
Keyword(s):  
Carbon Fibers ◽  
Composite Coatings ◽  
Microwave Absorbing Properties ◽  
Microwave Absorbing

Synthesis and Microwave Absorbing Properties of PyC/BN Composite Powders

2013 ◽  
Vol 28 (5) ◽  
pp. 479-484 ◽  
Author(s):  
Wei ZHOU ◽  
Peng XIAO ◽  
Yang LI ◽  
Heng LUO ◽  
Liang ZHOU
Keyword(s):  
Composite Powders ◽  
Microwave Absorbing Properties ◽  
Microwave Absorbing
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