carbon fiber processing 碳纤维加工制备

.,CarbonFiberProcessing,Productionmethods,propertiesandcompositeapplicationsCoreyBehrensFebruary19,2007,.,PropertiesofCarbonFibers,HighstrengthHighstiffnessWithstandtemperaturesto2500oCHighstrength/weightratioTensilemodulirangefrom4x106psito100 x106psi,.,MethodsofproducingCarbonFiber,AllcommercialC.F.sfrom3processes:Polyacrylonitrile(PAN)Rayon(cellulose)MesophasePetroleumPitchNewmethodfordiscontinuousC.F.VaporGrowth(highperformanceapplication),.,PANprocess,Accountsfor90%ofcommercialC.F.s93-95%acrylonitrileunitsPANdecomposesbelowitsmelttemperatureTrueMeltprocessnotpossibleThereforeextrudedintofilamentform,.,ProcessMethod,Copolymerisfirstdissolvedinsuitablesolvente.g.Dimethylacetamide15-30%polymerbyweightextrudedthroughaspinneretlarge#ofapprox.100mcapillaryholesenterscoagulatingbath(Wetspinning)Alsohotgasenvironments1-2stagesoffurtherstretchingAlignspolymermoleculesparalleltofiberaxisMolecularorientationmustbelockedintoplaceEffectsfinalmechanicalpropertiesofC.F.s,.,PANprecursorfiberprocess,.,ConsiderationsofPAN,WetspinningRequiresexcessivesolventNecessitatesremovalfromfiber,solventrecoveryTraceimpuritieslimitfinalC.F.propertiesBASFpseudo-meltalternativeAcrylonitrilecopolymerpolymerizedinaq.Soln.Purified,dewatered,pelletizedHomogenousmeltbelowdegradationtemp.EliminatesneedforexpensivesolventLowerwastewaterrequirements,.,BASFPANpseudo-melt,.,ProductionofCarbonFiberfromPAN,Heating/StretchingPre-carbonizationCarbonizationSurfaceTreatment,.,Chemistryofcarbonfiberproduction,.,Heating/Stretching,Stretching(500-1300%)220-270oCfor30minto7hrsTemp./Timedependentoncomposition/diameterofPrecursorChemicalchangesCyclizationofnitrilegroupsDehydrationofsaturatedC-CbondsOxidationGeneratesCO2andHCNLargefurnace+DriverollersControlledtensionessentialforalignmentPANcarboncontent:54%,.,Pre-carbonization,Heatingupto1100oCNon-CarbonelementsdrivenoffInitiallylargermoleculesCH4H2ONH3N2HCNCO2COSlowerheatingrate,.,Carbonization,1100oC2800OCOnlysmalldiatomicmoleculesH2N2FasterheatingratepossibleGraphitizationabove1800oCFinalCcontent:80%to99%Temp.dependentOverallYield:40-45%,.,SurfaceTreatment,ImprovesbondingwithpolymericmatrixmaterialsIncreasesoxygenatedgroupsatsurfaceGassingatelevatedtemps.SodiumhypochloritesolutionNitricAcid,.,C.F.sfromPANprecursorFibers,.,PANandPitchprocessing,.,Rayon(cellulose)precursorfibers,Typicallylowmodulus(4x106psi)Fiberheatedto400oC,pyrolizationofcelluloseCarbonizationat1000oCGraphitizedat2000oCHighmodulusobtainedbystretchingatfinalheattreatmentstage,.,MesophasePitchPrecursors,SamegeneralprocessasPANLowtensilestrengthofprecursorfibersMelt-spinisusedDonotrequirestretchingprocesstomaintainpreferredalignment,.,FinalCarbonFibers,Woven,Braided,orWoundUnidirectionallay-upsMulti-directionalweavesStrengthlimitingfactorsPurityofprecursorPrecursorvoidcontentTemperatureTension,.,C.F.sfromdifferingprocesses,.,Carbonvs.Steel,.,ModulusClassifications,Ultrahighelasticmodulustype(UHM)Highelasticmodulustype(HM)Intermediateelasticmodulustype(IM)Standardelasticmodulustype(HT)Lowelasticmodulustype(LM),.,CarbonFiberModulus,http:/www.carbonfiber.gr.jp/english/index.html,.,Compositeusesofcarbonfibers,Polymer-MatrixCompositesMetal-MatrixCompositesCarbon-MatrixCompositesCeramic-MatrixCompositesHybridcomposites,.,Carbon-CarbonComposites,CarbonsubstrateinCarbonaceousMatrixSameelementdoesnotsimplifycompositebehavioreachconstituenthasawiderangeofformsCarbonfiberscontinuousandwovenDisadvantagesHighfabricationcostPooroxidationresistancePoorinter-laminarproperties,.,FabricationofC-CComposites,Liquidphaseimpregnation(LPI)Hotisostaticpressureimpregnationcarbonization(HIPIC)HotpressingChemicalVaporInfiltration(CVI),.,ApplicationsofC-CComposites,AircraftBrakesHeatPipesReentryvehiclesRocketmotornozzlesHipreplacementsBiomedicalimplantsToolsanddiesEnginepistonsElectronicheatsinksAutomotiveandmotorcyclebodiesBicycles,.,Buckley,JohnD.andDan.D.Edie,eds.Carbon-CarbonMaterialsandComposite