北化大材料导论讲义第4章 复合材料(共4学时)(彩色版)

NaturallyOccurringCompositesWood:cellulosefibersinaligninmatrix.Bone:shortandsoftcollagenfibersembeddedinamineralmatrixcalledapatite.Glassfiberreinforcedresinshavebeeninusesinceaboutthe1940s.StiffnessStrengthWeightFatigueresistanceComparisonbetweenconventionalmonolithicStiffnessStrengthWeightFatigueresistanceComparisonbetweenconventionalmonolithicmaterialsandcompositematerials.SteelAluminumCompositesThermalexpansion定义1Amixtureoftwoormorematerialsthataredistinctincompositionandform,eachbeingpresentinsignificantquantities(e.g.,>5%)。两种或多种不同组成、不同存在形式材料的混合物，各以显著的量存在定义2Theunionoftwoormorediversematerialstoattainsynergesticorsuperiorqualitiestothoseexhibitedbyindividualmembers两种或多种不同材料的结合体，可获得协同的或优于个别材料的质量增强材料增强材料高分子材料PMCCMCMMCCMC陶瓷材料金属材料陶瓷材料复合材料按结构分类基本假定纤维与基体必须紧密结合。纤维必须是连续的或在长度方向上搭接的。存在一个临界纤维体积分数Vfcrit,高于此值方能发生纤维增强。存在一个临界纤维长度，高于此值方能发生4.2.1应力平行于纤维，等应变f与m分别代表纤维与基体。模量加和规律模量加和规律由等应变假定Ec=EfVf+EmVm求受力比故有FEVfFEV FEVmmm复合材料模量预测（复合材料模量预测（1）EXAMPLEPROBLEM4.1Acontinuousandalignedglassfiber-reinforcedcompositeconsistsof40vol%ofglassfibershavingamodulusofelasticityof69GPaand60vol%ofapolyesterresinthat,whenhardened,displaysamodulusof3.4GPa.(a)Computethemodulusofelasticityofthiscompositeinthelongitudinaldirection.(b)Ifthecross-sectionalareais250mm2andastressof50MPaisappliedinthislongitudinaldirection,computethemagnitudeoftheloadcarriedbyeachofthefiberandmatrixphases.(c)Determinethestrainthatissustainedbyeachphasewhenthestressinpartbisapplied.AAcontinuousandalignedglassfiber-reinforcedcompositeconsistsof40vol%ofglassfibershavingamodulusofelasticityof69GPaand60vol%ofapolyesterresinthat,whenhardened,displaysamodulusof3.4GPa.(a)Computethemodulusofelasticityofthiscompositeinthelongitudinaldirection.SOLUTION(a)ThemodulusofelasticityofthecompositeiscalculatedusingEquationEc=EmVm+EfVf:Ec=(3.4GPa)(0.6)+(69GPa)(0.4)=30GPaAcontinuousandalignedglassfiber-reinforcedcompositeconsistsof40vol%ofglassfibershavingamodulusofelasticityof69GPaand60vol%ofapolyesterresinthat,whenhardened,displaysamodulusof3.4GPa.(b)Ifthecross-sectionalareais250mm2andastressof50MPaisappliedinthislongitudinaldirection,computethemagnitudeoftheloadcarriedbyeachofthefiberandmatrixphases.Solution:Firstfindtheratiooffiberloadtomatrixload,AAcontinuousandalignedglassfiber-reinforcedcompositeconsistsof40vol%ofglassfibershavingamodulusofelasticityof69GPaand60vol%ofapolyesterresinthat,whenhardened,displaysamodulusof3.4GPa.(b)Ifthecross-sectionalareais250mm2andastressof50MPaisappliedinthislongitudinaldirection,computethemagnitudeoftheloadcarriedbyeachofthefiberandmatrixphases.ThetotalforcesustainedbythecompositeFc:Fc=Acσ=(250mm2)(50MPa)=12,500NThistotalloadisjustthesumoftheloadscarriedbyfiberandmatrixphases,thatis13.5Fm+Fm=12,500NorFm=860NwhereasFf=Fc-Fm=12,500N-860N=11,640NAcontinuousandalignedglassfiber-reinforcedcompositeconsistsof40vol%ofglassfibershavingamodulusofelasticityof69GPaand60vol%ofapolyesterresinthat,whenhardened,displaysamodulusof3.4GPa.Thecross-sectionalareais250mm2andastressof50MPaisapplied.(c)Determinethestrainthatissustainedbyeachphasewhenthestressinpartbisapplied.Forstresscalculations,phasecross-sectionalareasarenecessary:Am=VmAc=(0.6)(250mm2)=150mm2Af=VfAc=(0.4)(250mm2)=100mm2ThusThus,Finally,strainsarecomputedas4.2.2外力垂直于纤维：等应力复合材料的应变可表示复合材料模量预测（2）(3.4GPa)(69GPa)(3.4GPa)(69GPa)(0.6)(69GPa)+(0.4)(3EXAMPLEPROBLEM4.2ComputetheelasticmodulusofthecompositematerialdescribedinExampleProblem4.1,butassumethatthestressisappliedperpendiculartothedirectionoffiberalignment.SOLUTIONAccordingtoEquation17.16,Ec=4.2.3基体的塑性流动基体发生塑性流动时，复合材料的极限强度可表示为：mm其中σfu是纤维的极限拉伸强度，σ’m是应变硬化基体的流动应力。复合材料的极限强度σcu必然高于基体的极限强度：4.2.3基体的塑性流动4.2.3基体的塑性流动可导出发生增强的临界纤维体积分数Vfcrit：4.2.4应力传递4.2.44.2.4应力传递Positionστ临界纤维长度：l=fcc2τc σfu=d2τ临界长度StressStressStressMaximuml/2l/2StressStressStressMaximuml/2l/2σl=lσσσl<lappliedloadl/2l/2 σσl>lσσσ非连续纤维整齐排列，复合材料的强度可以按下式修非连续纤维整齐排列，复合材料的强度可以按下式修非等长纤维：只要l<lc，以上分析仍对比σcu=σfuVf+σ’mVm热塑性基体聚酰胺、聚碳酸酯、聚砜、聚苯硫醚、聚醚醚热塑性基体聚酰胺、聚碳酸酯、聚砜、聚苯硫醚、聚醚醚酮、氟塑料聚合物基体热固性基体聚苯硫醚(PPS)聚砜(PES)聚醚醚酮(PEEK)===-S-nOS---S--nOn=OC--n-O=OC--nImportantcharacteristics1.Asmalldiameter2.Ahighaspectratio3.AveryhighdegreeofflexibilityFlexibilityTheflexibilityFlexibilityTheflexibilityofamaterialisdeterminedbyshape,sizeofthecrosssection,anditsradiusofcurvature.Wecanusetheinverseoftheproductofbendingmoment(M)andtheradiusofcurvature(R)asameasureofflexibility.25nylon252015glassmulliteCCZrOBSiC5SiNAlO50100200300400500E(GPa)Fiberdiameterofmaterialswithflexibilityequaltothatofa25-μm-diameternylonfiber. 加热 加热BCl/H气相沉积钨丝预热卷取H4.4.1BoronFibers硼纤维Chemicalvapordeposition(CVD)化学气相沉积法2BX3+3H22B+6HX 加热AboronfilamentproductionfAboronfilamentproductionfacilityReactionzoneW2B5ReactionzoneW2B5+WB4BSiCW4.4.1硼纤维拉伸强度：2.1~5.1GPa模量：~400GPa4.4.2CarbonFibers碳纤维碳含量在92~95%之间，模量在344GPa以下的为碳纤维，碳含量在99%以上，模量在344GPa以上的为石墨纤维。在1300°C左右热解的称碳纤维在1900°C以上热解的称石墨纤维OxidationCarbonizationOxidationCarbonizationupto250°C250~1500°C4.4.2碳纤维与石墨纤维Graphitization1500~2500°CHHHHHHHHHCNHCNHCNHCNCCCCCCCCHCHCHCHCLaddermoleculeHHHHHHHHpolyacrylonitrileNNNNΔEx-PitchCarbonEx-PitchCarbonFibersSourcesofpitchPolyvinylchloride(PVC)PetroleumasphaltCoaltarPropertiesofdifferentcarbonfibersPrecursorDensity(g/m3)Young'smodulusElectricalresistivity(10-4Ω_cm)RayonPolyacrylonitrilePitch(Kureha)41HT41Mesophasepitch2.19HTSingle-crystalgraphite2.25l0004.4.3OrganicFibersKevlar®O4.4.3OrganicFibersKevlar®OOC4.4.3有机纤维拉伸强度3.4GPaKevlar49：模量130GPaKevlar149：模量180GPaCH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2Spectra聚乙烯纤维CH2CH24.4.3有机纤维：聚乙烯纤维聚乙烯溶液聚乙烯溶液烘箱冷却4.4.3有机纤维聚乙烯纤维的性质性质Spectra900Spectra1000密度(g/cm3)0.970.97直径(μ)3827拉伸强度(GPa)2.73.0拉伸模量(GPa)119175Kevlar1494.4.4CeramicFibers陶瓷纤维Threefabricationmethods1.Chemicalvapordeposition2.Polymerpyrolysis3.Sol-geltechniques-DryspinningPrecursorfiber(organoaluminum-DryspinningPrecursorfiber(organoaluminumpolymerandalkylsilicate)CalcinationInorganicfiberAlO:70-100%SiO:30-0%OrganoaluminocompoundAlkylaluminumoralkoxyPolymerizationTheSumitomoprocessofmakingasilica-stabilizedAlOfiberSi-containingcompound(alkylsilicate)-Al－O-Raluminum(AlR)Organicsolvent+AlR+HOThe3MCo.processofmakingAl2O3fiberPumpPumpSpinneretPyrolysisTakeupspoolDrawwheelsFilterSolreserviorfurnaceCompositionandpropertiesofCompositionandpropertiesofNextelseriesfibersNo.CompositionDiameterDensityTensileYoung’s(wt%)(μm)(g/cm)strength(MPa)modulus(GPa)312AlO62,SiO24,BO1410-122.71700152440AlO70,SiO28,BO210-123.052000186550AlO73,SiO2710-123.032000193610AlO99+,(SiO,FeO)10-123.751900370720AlO85,SiO1510-123.42130260OpticalOpticalmicrographofNextel312(Al2O3+SiO2+B2O3)Density(g/cm3Density(g/cm3)3.3Diameter(μm)CVDSiliconCarbideFibersCH3SiC13(g)H2HCl(g)PropertiesSiC(s)+3TensileYoung’sstrengthmodulus (MPa)(GPa)35004304.4.5GlassFiber55%二氧化硅，20%氧化钙，15%氧化铝，10%氧化硼拉伸强度：5GPa（Electricalapplication）10%氧化镁，25%氧化铝，65%二氧化硅拉伸强度：7GPa（HighStrength）BatchmixingBatchhopperBatchmixingBatchhopperFurnacemeltingareaPlatinumbushingGlassfibermanufactureFilamentcollectingandsizeapplicatorStrandtraversemotionWindingheadunitChoppedChoppedstrand4.4.5玻璃纤维continuousyarncontinuousyarnFabricRovingFabricRoving4.4.6Wiskers4.4.6Wiskers晶须单晶接近理论强度（1~2万MPa）直径：几μ至几mm长径比：50~10000缺点：尺寸不均一性能不均一 研磨 焦化破碎 研磨 焦化破碎4.4.6晶须：谷糠法碳管反应器碳管反应器>1600°C拌匀分离残糠拌匀分离残糠烘干脱碳碳化硅晶须30μ的固体催化剂30μ的固体催化剂4.4.6晶须：VLS法1400°C3C+SiO2SiC+2COH2CH4液体催化剂含过饱和Si与C4.5界面InterfaceThebehaviorofacompositematerialisaresultofthecombinedbehaviorofthefollowingthreeentities:FiberorthereinforcingelementMatrixFiber/matrixinterfaceLiquidVaporLiquidWettabilityLiquidVaporLiquidWettabilityPartialWettingCompleteWettingθ=0°LiquidVapor ImportanttypesofinterfacialbondingMechanicalbondingPhysicalbondingChemicalbondingMechanicalbondingVoid(a)MechanicalbondingVoid(a)Goodmechanicalbonding(b)LackofwettabilityMatrixFiberMatrixFiberPhysicalBondingAnybondinginvolvingweak,secondaryorvanderWaalsforces,dipolarinteractions,andhydrogenbondingcanbeclassifiedasphysicalbonding.Thebondenergyinsuchphysicalbondingisapproximately8-16kJ/mol.PhysicalBondingTwoPhysicalBondingTwopolymersurfacesmayformabondowingtothediffusionofmatrixmoleculestothemolecularnetworkofthefiber,thusformingtangledmolecularbondsattheinterface.ChemicalBondingAtomicormoleculartransport,bydiffusionalprocesses,isinvolvedinchemicalbonding.Solidsolutionandcompoundformationmayoccurattheinterface.Thisencompassesalltypesofcovalent,ionic,andmetallicbonding.Chemicalbondinginvolvesprimaryforcesandthebondenergyintherangeofapproximately40-400kJ/mol.ChemicalBondingCouplingagents(silanesChemicalBondingCouplingagents(silanesarethemostcommonones)areusedforglassfibersinresinmatrices树脂基复合材料热塑性树脂基热固性树脂基树脂基复合材料热塑性树脂基热固性树脂基复合材料复合材料低性能高性能中温型中温高强型高温型不饱和聚酯酚醛环氧树脂聚酰亚胺热塑性树脂基复合材料维维-酚醛基复合材料（中温型）布布环氧树脂基复合材料（中温高强型）23高温型塑料基复合材料高温型塑料基复合材料聚酰亚胺双马来酸酐树脂50%玻璃纤维树脂68.3%T300碳纤维57.7%2.00工作温度(°C）260-260230230230拉伸强度(MPa）200-400400-模量(GPa）4.04.7.64.7.6预制片(Prepreg)制备PreformStructuresCarbonCarbonfiberImpregnationCFRC2500-3000°CPolymerorpitchbinderGreenfabricationFirstcarbonizationupto1000°CLiquidimpregnationwithpolymerorpitchCuringofthepolymerPressurecarbonizationofthepitchCarbonization1000°CCFRC1000°CFinalgraphitization2500-3000°CIntermediatecarbonization1300-1900°CH2H2HydrocarbonOriginalfibersubstrateDepositionTheinductionfurnacesusceptor(1)Isothermal(2)Pressuredifferential(3)ThermalgradientInductioncoilsJacketGraphitesusceptorH2H2CarbonsubstrateCarriergasH2CarbonsubstrateSleeveJacketGraphitesusceptorHydrocarbongasCarriergasTheinductionfurnacesusceptor(3)ThermalgradientInductioncoilsLowso.Lowso.fteningpoints,lowviscosityintheliquidstageandhighgraphiticyield.PitchResinProcessingFormlargesheet-likemoleculesuponpolymerization,notacross-linked3-Dnetwork,asinthecaseofthermosettingresinsmeltedpitch650°C,meltedpitch650°C,108.4MPa24hinductionfurnace2300°CPressure3-Dwovenfabricsandcuring3-Dwovenfabricsandcuringformsilicondioxide1650°C,siliconcarbideformedsilicaandaluminapowderandpyrolyzedPreparationofRocketnozzlestreatmentwithtetraethylorthosilicateimpregnatedwithtrimmingandpyrolyzingimpregnatedwithfurfurylalcoholOxidationBehaviorandProtectionWeightloss(%)AWeightloss(%)ABAir200ml/min6543CC/CSheetA2.3mmB2.7mmC5.5mmD7.9mm2D10TemperatureCoatingthroughCVDSiliconcarbide,titaniumcarbideandboronnitrideCoatingthroughCVDSiliconcarbide,titaniumcarbideandboronnitride(高温效果不佳)Boronoxideorborates(1000°C以上或水蒸气存在下效果不佳)Boratesalsowerefoundtohemoreeffectivewhentheyweremixedwithparticulaterefractoryphasessuchaszirconiumandhafniumborides.C/Ccompositeswithsuccessivelayersofboronoxide,zirconiumborideandsiliconcarbidecanpreventoxidationattemperatureashighas1500°Cindryair.SurfaceCarbideConversionConversionofthecarbonsurfaceofthecompositetoanoxidationresistantcarbide.ChemicalreactionbetweencarbonandmeltedsiliconwillformsiliconcarbidelayeronthesurfaceofC/Ccomposite.碳碳复合材料的典型性能（括号中为1900碳碳复合材料的典型性能（括号中为1900°C下数据）X-Y度ApplicationsAerospaceindustry(jet-aircraftbrakelinings)Medicalimplantation,astheyofferbiocompatibility.Carbonfiber