Study On The Application Of The Graphite Intercalation Compound In Millimeter Wave Passive Countermeasure

The millimeter wave guidance and detecting are being one of the importantdevelopment trends at present. Expanded graphite are used for forming camouflageshield screening that attenuate effective millimeter wave transmission, because of thefeatures of hollow cavity structure , feasible floating performance and powerfulelectric conductivity. In this dissertation, some problems in MMW passivecountermeasure application of the conventional H₂SO₄-GIC, HNO₃-GIC are analyzed.Several kinds of graphite intercalation compounds with easy low temperature expansion arefabricated, taking the theoretical calculation result of relationship betweentemperature and expanded volume of GIC as the instruction. The structure, elementcontents and magnetism performance of GIC are characterized and discussed and thecharacteristics of easy low temperature expansion, high expansion volume and low energyconsumption are studied.The millimeter wave dynamic attenuation performances andthe effect factors of expanded graphite are studied systematically. The main contentsare as follows:(1)Based on the Griffith crack theory, the theoretical model of pore growthduring thermal expansion of GIC is established. C₂H₅COOH, C₃H₇COOH, CH₃NO₂,HCIO₄, H₃PO₄ are used as intercalant of GIC, according to the calculation result ofrelationship between temperature and expanded volume.(2) The GICs are prepared by chemical oxidation method using CrO₃,KMnO₄ asoxidant. The sandwich structure, appearance and composition of GIC arecharacterized by using SEM, EDS, XRD, FTIR. The XRD results show thatC₃H₇COOH-FeCl₃-GIC is 2, 3 stage, others are all 1-stage. The VSM results showedthe GIC different from the pure graphite diamagnetism, display paramagnetism andthe expanded graphite's stronger, because of the FeCl₃ intercalated.(3)The weight loss process and decomposition reaction course of GICs areanalyzed by using TG, DSC technologies. Results show that the thermaldecomposition temperature of the GICs are 135～160℃, the conventional H₂SO₄-GICis about 250℃. The results of relationship between temperature and expanded volumeshow that the GICs obtain tugher expansion volume in low temperature, when GICparticle size are uniform. The experiment results of GIC percent in interference agentindicate the easy low temperature expansion GIC reach 75%, however, the conventionalH₂SO₄-GIC, HNO₃-GIC is only 55%. The low energy consumption performance ofthe easy low temperature expansion GIC is studied by analyzing the theoretical calculation result of combustion temperature.(4)The 3mm and 8mm dynamic attenuation characteristics effect factors of theeasy low temperature expansion GIC are studied systematieaUy. Compared withconventional H₂SO₄-GIC, the 3ram and 8mm attenuation decibels ofCH₃NO₂-FeCl₃-GIC improve 2.29 dB, 4.01 dB respectively under the same mass ofinterference agent.The magnetic expanded graphite in which pores adsorbed iron oxide areprepared by expanding mixture of ferrocene and GIC under high temperature. Withthe increase of iron oxides content, the mean conductivity of composites drop slowly,however, the magnetization intensity strengthen gradually. The magnetic expandedgraphite attenuation millimeter wave possess absorption both electric loss andmagnetic loss. These two kinds of absorption restrict each other. The 3mm, 8mmwave dynamic attenuation capability is strongest, when the weight ratio of ferroceneand expandable graphite is 2～3: 5.The expanded graphite attenuation to MMW incompletely conforms to thehalf-wave theory, but is slightly smaller than the half-wave length. The attenuationcapability of expanded graphite obtain through interference agent is obviously betterthan through muffle furnace.