FeNi软磁合金吸波材料的设计与制备

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1、北京工业大学博士学位论文Fe-Ni软磁合金吸波材料的设计与制备姓名：张晓宁申请学位级别：博士专业：材料学指导教师：周美玲;王群20031001ABSTRACTABSTRACTTheaimofthisdissertationiStoprovidetheoreticalevidenceandpracticalapplicationsforresearchinganddevelopingnewtypeelectromagneticwaveabsorbers．Thisinvestigationwillshowseveraldisadvantagesinthetraditionaltypesofapp

2、liedelectromagneticwaveabsorbingmaterialswhosewaveabsorbersareferriteorSiCpowders：narrowingtheabsorbingfrequencybands，enlargingtheirthickness，andweakeningtheeffectivenessoftheirabsorption．Inordertomakesubstitutionsfortraditionaltypesofelectromagneticwaveabsorbers．forthefirsttimea“shell-core’’struct

3、uretheoreticalmodelwillbeoutlinedanddiscussed．Afterconsideringmaterialapplicationsandtherelationshipsofmicrostructureversuselectromagneticcharacteristics，‘'shell—core”structurecompositepowders，thenewtypewaveabsorberswhichpossessFeNi3，Y一(Ve，Ni)andFe304phasesandwerepreparedbyusingthemethodof“mechanic

4、alalloying+oxidation+re—crystallizingheattreatment”willbedescribed．Themicrostructureofthe“shell．core”structurecompositepowderswasstudiedbymeansofmodemmaterialanalyzingtechniques，includingXRD，MFM，FEG-SEM，EDS，andSOon．ItWasprovedthatthecomplexmagneticpermeabilitybenefitSfromtheincreasingaveragecrystal

5、grainsize，thedecreasingmagneticdomainwidthandwallthicknessofthenewtypewaveabsorbers；the“shelllayer’’whichpossessesFe304phasecallbeeffectivetoreducecomplexelectricpermittivity．Twokindsofsingle·-layeranddouble-·layerflattypecompositescontainedwithinthe“shell—core”structurecompositepowderswhosegraingr

6、anularityWaSunderlOktmweremanufactured．Thesenewtypesofelectromagneticabsorbingmaterials，aSwellastheabsorbingmechanismwillbedeeplyanalyzed．Thedouble—layerabsorbingphysicalmodel“matchleadinglayer+electromagneticdissipationlayer'’willbediscussedandevaluatedbytheoreticalcalculationsofabsorbingeffective

7、ness(AE)onflattypecompositesastheywerecarriedoutviadeduceddouble—layerabsorbingformulaeandcomputer-aideddesignofmaterials．AEtheoreticalcalculationvaluesconformedtoAEtestingvaluesofabsorbingmaterialswithlami