检索结果-南通市图书馆

Effect of deposition temperature on SrFe12O19@carbonyl iron core–shell composites as high-performance microwave absorbers

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2020年第6期29卷 505-511页

作者：刘渊李茸贾瑛何祯鑫 Xi’an Research Institute of High Technology Xi’an 710025China

The SrFe12O19@carbonyl iron(CI) core–shell composites used in microwave absorption are prepared by the metal–organic chemical vapor deposition(MOCVD). The x-ray diffractometer, scanning electron microscope, energy dispersive spectrometer, and vector network analyzer are used to characterize the structural, electromagnetic, and absorption properties of the composites. The results show that the SrFe12O19@CI composites with a core–shell structure could be successfully prepared under the condition: deposition temperatures above 180℃, deposition time 30 min, and gas flow rate 30 m L/min.The electromagnetic properties of the composites change significantly, and their absorption capacities are improved. Of the obtained samples, those samples prepared at a deposition temperature of 180℃ exhibit the best absorption performance.The reflection loss of SrFe12O19@CI(180℃) with 1.5 mm–2.5 mm in thickness is less than-10 dB in a frequency range of 8 GHz–18 GHz, which covers the whole X band and Ku band.

关键词： SrFe12O19 carbonyl iron electromagnetic properties microwave absorption

Electromagnetic parameters and microwave-absorption properties for the mixtures of mechanically milled spherical and flaky carbonyl iron powders

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2012年第3期25卷 201-206页

作者： Jinghua HE Wei WANG Aimin WANG Jianguo GUAN State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan Universityof TechnologyWuhan 430070China

The electromagnetic parameters were measured for the mixtures of mechanical milled carbonyl iron powders （CIPs） with different mass ratios of spheroid-like particles to flake-shape particles. The results indicate that mixing the sphere-like CIP particles with flake-shaped CIPs can be used to adjust effectively the electromagnetic parame- ters and enhance the absorption property in high frequency. In addition, a theoretic simulation based on the principle of superposition was carried out and compared with the microwave measurement results, indicating that the simple principle of superpo- sition can not reflect truly the internal interaction mechanism in the composites with different particle shapes.

关键词： carbonyl iron Mechanical milling Electromagnetic property Microwave-absorption property

Electromagnetic Characterization of Recyclable Polymer Nanofibers Based on PSU/carbonyl iron

在线全文

学校读者我要写书评

暂无评论

Journal of Renewable Materials 2019年第3期7卷 279-287页

作者： Daniel Consoli Silveira Tiago Teixeira da Silva Braga Daniel Molina Gil Newton Adriano dos Santos Gomes Lilia Müller Guerrini Edson Cocchieri Botelho Department of Materials and Technology Sao Paulo State University(UNESP)School of EngineeringGuaratinguetá/SP-Brazil Electronic Warfare Laboratory Technological Institute of Aeronautics(ITA)Sao Josédos Campos/SP-Brazil Institute of Science and Technology Federal University of Sao Paulo(UNIFESP)Sao Josédos Campos/SP-Brazil

This study investigated and defined the optimal processing parameters for the electrospinning of polysulfone polymer solutions with N,N-dimethylacetamide.Variation of parameters such as solute concentration,electrical voltage,and working distance were correlated with the quality of the obtained nanofibers using morphological characterization via scanning electron microscopy(SEM).carbonyl iron additive was dispersed in the polymer solutions,using ultrasonic tip,and the material processed via electrospinning with aforementioned parameters defined.Nanofibers with the property of interaction with electromagnetic waves were obtained.The dispersion of different concentrations of the additive and electromagnetic characterizations in the X-band of microwaves(8.2 and 12.4 GHz),using vector network analyzer(VNA)and rectangular waveguide,allowed the identification of the materials electromagnetic behaviors.Scattering parameters allowed the calculation of reflected and transmitted energy by the material.

关键词： carbonyl iron electromagnetic characterization electrospinning nanofibers polysulfone

Microwave Absorption Properties of the carbonyl iron/EPDM Radar Absorbing Materials

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2007年第2期22卷 266-270页

作者：冯永宝 College of Materials Science and Engineering Nanjing University of Technology

Employing carbonyl iron powder and Ethylene-Propylene-Diene Monomer （EPDM） as the absorbent and matrix, rubber radar absorbing materials （RAM） were prepared. Effects of the carbonyl iron volume fraction and the thickness of the RAM on the microwave absorption properties in the frequency range of 2.6-18GHz were studied, and a mathematical analysis was made using the electromagnetic theory. The experimental results indicate that the minimum reflectivity of the radar absorbing materials continuously decreases with the increase of the carbonyl iron volume fraction, and the absorption peak also moves towards the low frequency for the same thickness of the RAM. The minimum reflectivity of the 3.0 mm RAM is -21.7dB at 3.5 GHz when the volume fraction of carbonyl iron is 45%. The reflectivity of the RAM is not in direct proportional to the thickness of the RAM, when the RAM has the same volume fraction of the carbonyl iron. The reflectivity of the RAM presents a regular trend at a given carbonyl iron volume fraction in the frequency range of 2.6-18 GHz. With the increase of the thickness, the maximum absorption peak moves towards low frequency band, the minimum reflectivity firstly decreases and then increases, and the absorption bandwidth for reflectivity〈-10 dB firstly increases and then decreases. The microwave absorption properties of the RAM are determined by the thickness and the composition of the radar absorbing materials. Theoretical analysis indicates that the reflectivity of the RAM is determined by the matching degree of the air＇s characteristic impedance and the input impedance.

关键词： EPDM radar absorbing materials （RAM） carbonyl iron reflectivity

Model of In Situ Composite of Cobalt(Ⅱ)-Phthalocyanine and carbonyl iron for Organic/Inorganic Nanocomposites

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2001年第1期16卷 1-4页

作者：龚荣洲 Huazhong University of Science and Technology Wuhan University of Technology

Cobalt-phthalocyanine/iron nanocomposite particles have been obtained using method of composite in situ, with the mixture of carbonyl iron and solution of cobalt ( Ⅱ ) - phthalocyanine (Co-Pc) ultrasonic dispersing in N,N-dimethyl-formamide (DMF). Structure characterization of their inner and surface have relation with method of carbonyl iron joined in the mixture, contents of carbonyl iron and Co-Pc in the mixture of Co-Pc ultrasonic dispersing in DMF. With a method of composite in situ controlling reasonable experiment condition, it can be obtained that cobalt-phthalocyanine/iron nanocomposite particles has completely been covered with Co-Pc, they had structure of Chinese gooseberry in inner and mere made up of almost regular spherical shape and the average diameter is 1. 4 μm.

关键词： composite in situ nanocomposites model structure characterization carbonyl iron cobalt ( Ⅱ ) -phthalocyanine

Multicomponent induced localized coupling in Penrose tiling for electromagnetic wave absorption and multiband compatibility

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第35期130卷 86-92页

作者： Xinran Ma Yuping Duan Lingxi Huang Ben Ma Hao Lei Key Laboratory of Solidification Control and Digital Preparation Technology(Liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian 116085China

In the electronic information and intelligent era, microwave absorption materials have been focused on the issue of electromagnetic(EM) pollution, but high-performance absorbers with thin thickness are highly desirable. The positive action between structural design and component selection can be regarded as a function to optimize the microwave loss capacity, which contributes to understanding the response mechanisms from the micro and macro. Therefore, we designed the absorber with quasiperiodic structures of Penrose tiling that has finely engineered the location of maximum absorption peak, the spherical carbonyl iron in thin rhombus, and flakey carbonyl iron in fat rhombus, the effective absorption bandwidth(Reflection Loss ≤ –10 d B) was realized from 6.46 GHz to 15.78 GHz in the 2 mm thickness. The unique arrangement of Penrose tiling can respond alternatingly to EM waves at large scales, and multicomponent coupling is distinctly in the neighboring unit cells. In addition, spraying aluminum pigment as the upper layer, the infrared emissivity is less than 0.35 to meet the complex application environment.This work opens up novel ideas on quasiperiodic structure combined multicomponent and injects infinite vitality to provide prospects for broadband responsive and high-efciency EM absorbers.

关键词： Microwave absorber Penrose tiling carbonyl iron Localized coupling

Microwave Permeability Change of FeCo Nanocrystalline During High Energy Ball Milling

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2006年第1期21卷 16-18页

作者：王维官建国 State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070China

The microwave magnetic properties of the ball milled FeCo panicles were investigated as functions of ball milling time （ t ） using microwave electromagnetic parameters analysis techniques. The results show that the imaginary part of intrinsic dynamic permeability （ ui ） of the ball- milled panicles is much bigger than that of raw powders. ui strongly depends on t and exhibits several slightly damped ferromagnetic resonances. These phenomena are in qualitative agreement with the formation of the corresponding microstructure or the Aharoni ＇ s model of non-uniform exchange resonance modes. The present microwave permeabilhy behavior indicates that nanocrystalline materials with the same grain size may exhibit different properties that depend upon the microstructure, which provides a possibility for manufacturing high performance microwave absorber.

关键词： high energy ball milling carbonyl iron cobalt alloy nanocrystalline microwave electromagnetic parameters

XRD and HRTEM Analyses of the Ball Milled Nanocrystalline FeCo Alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2006年第1期21卷 68-71页

作者：王琦官建国 State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070ChinaSchool of Materials Science and EngineeringJinan UniversityJinan 250022China State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070China

The nanostractures of the ball milled FeCo particles were characterized as functions of the ball milling time （ t ） using quantitative X- ray diffraction （ XRD ）, high resolution transmission electron microscopy （HRTEM） analysis techniques. The results show that the nanocrystalliue bcc FeCo particles are available using carbonyl iron and cobalt powders as the start materials during the high-energy ball milling. At the early stage of ball milling, Co powders are easily mashed into nanocrystalllites, by which the surface of the larger Fe particles of about 80- 150 nm is coated. With t increasing, the refinement of grain size and the incorporation of defects including dislocations, disclinations and grain boundaries happen, and then FeCo alloy with a certain layered structure is formed, finally the layered stractare disappears with the formation of isotropic grains having a steadystate grain size in the nanometer regime after a certain period of t.

关键词： high energy ball milling carbonyl iron cobalt alloy nanocrystalline materials

Reaction of [(μ -RE)(μ -CO)Fe_2(CO)_6]-[Et_3NH]^+ (E=S, Se, Te)Salts with Benzenesulfinyl Chloride and Carbon Disulfide

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 1999年第11期10卷 973-974页

作者： Chao Guo YAN(Department of Chemistry, Yangzhou University, Yangzhou 225002) Department of Chemistry Yangzhou University Yangzhou 225002 China

The salts of [(μ -RE)(μ-CO)Fe2(CO)6] -[Et3NH]+(E = S. Se, Te) react withbenzenesulfinyl chloride to give the μ -sulfinyl group bridged complexes (μ-RE)(μ- PhS=O)Fe2(CO6), in good yields. Whereas the salts [(μ -RS)(μ -CO)Fe2(CO)6]-[Et_3NH]+(R =t- Bu, Ph) react with carbon disulfide to yield the dithioformato-bridged anionic salts [(μ -RS)(μ- S=C-S)Fe2(CO)6]-[Et3NH], which react in situ at the exo-sulfur atom of the dithioformato-groupwith diverse α.β-unsaturated carbonyl compounds to give Michael addition products inmoderate yields.

关键词： Cluster carbonyl iron sulfur selenium synthesis.