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Preparation and Microwave Absorbing Properties of Metal Composite Nanoplates

Author: HuangZuoHui
Tutor: JiGuangBin
School: Nanjing University of Aeronautics and Astronautics
Course: Physical and chemical
Keywords: carbonyl iron thermal decomposition microwave absorbing FeCoSm compositematerials
CLC: TB333
Type: Master's thesis
Year: 2013
Downloads: 12
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Abstract


The morphology and structure of the magnetic material are the two key factors which affect itsabsorbing properties. In this work, carbonyl iron-graphene nanocomposite and FeCoSm metalcomposites with flaky morphology were fabricated using a simple and low cost method whichcombining the thermal decomposition and mechanical milling, respectively. The morphology andcrystal structure of samples were characterized by XRD, SEM, TEM, FT-IR and Raman spectroscopy,while its magnetic properties and electromagnetic parameters were investigated by VSM and vectornetwork analyzer. The frequency dependence of microwave absorbing properties in different thicknesswas calculated by the reflection loss formula.The carbonyl iron-graphene composite materials prepared by the liquid thermal decompositionof iron carbonyl and possess laminar morphology, the carbonyl iron nanoparticles loaded at thesurface and inter layer of the multi-graphene with the diameter of about20100nm. The resultsrevealed that the samples with the decomposition time of360min have the highest saturationmagnetization of113emu/g. When mixed with paraffin （whoes mass ratio is about83%）, thereflection loss values less than10dB in the frequency range of1016GHz with a thickness of1.5mm. When the thickness of the composite is3mm, the reflection loss up to the maximum of25dBat the frequency of4.3GHz. The carbonyl iron-graphene composites prepared via a one-step thermaldecomposition method also have a flaky structure with the iron particles in uniform size and wellcoated on the multi-graphene. When the vapor decomposition time of the sample was120min, thecomposite have the highest saturation magnetization of46emu/g; the reflection loss value below-5dB in the frequency range of1018GHz when mixed with paraffin （80wt%） with a thickness of1.5mm, and the maximum absorption value is-11dB at the frequency of13GHz with a thickness ofabout3mm. It can be indicated that the carbonyl iron-graphene nanocomposite is a potential lightmaterial in the field of radar absorbing.The rare earth element Sm was doped into FeCo alloy, and Fe50Co50Sm2was selected as the basissample after considering both the structure and the performance parameters of the material. Alloyribbons were obtained by rapid quenching melt spinning method with Fe50Co50Sm2alloy ingot assource material. Subsquently, the alloy ribbons converted to flaky alloy by mechanical ball milling.The optimal parameters to prepared the flaky Fe50Co50Sm2is using acetone as the milling media andcalcium stearate （0.5%） as milling aid with the milling time of2hours. The reflection loss valuelower than-5dB in the frequency range of7.315.8GHz when mixed with paraffin （70wt%） with athickness of1mm, and the maximum absorption value is-15.4dB at the frequency of11GHz with a thickness of about2mm.

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