carbon fiber processing 碳纤维加工制备

CarbonFiberProcessing Productionmethods propertiesandcompositeapplicationsCoreyBehrensFebruary19 2007 PropertiesofCarbonFibers HighstrengthHighstiffnessWithstandtemperaturesto 2500oCHighstrength 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 100 mcapillaryholesenterscoagulatingbath 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 1100oC 2800OCOnlysmalldiatomicmoleculesH2N2FasterheatingratepossibleGraphitizationabove 1800oCFinalCcontent 80 to 99 Temp dependentOverallYield 40 45 SurfaceTreatment ImprovesbondingwithpolymericmatrixmaterialsIncreasesoxygenatedgroupsatsurfaceGassingatelevatedtemps SodiumhypochloritesolutionNitricAcid C F sfromPANprecursorFibers PANandPitchprocessing Rayon cellulose precursorfibers Typicallylowmodulus 4x106psi Fiberheatedto400oC pyrolizationofcelluloseCarbonizationat 1000oCGraphitizedat 2000oCHighmodulusobtainedbystretchingatfinalheattreatmentstage 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 CarbonMaterialsandComposites