硅酸盐学报英文模板

342013Cr2AlC-Fe(100044)Cr2AlC-FeXCr2AlCCr2AlCCr2AlCCr2AlC30%1417MPaTB333A0454–5648(2013)01–FabricationofCr2AlCFe-basedCompositesbyin-situReactionMethodCHENXinhuaZHAIHongxiangWANGWenjuanHUANGZhenying(CenterofMaterialsScienceandEngineering,SchoolofMechanicalandElectronicControlEngineering,BeijingJiaotongUniversity,Beijing100044)Abstract:ACr2AlC-Fecomposite,whichcouldhavepotentialapplicationsinnuclearenergyindustryasengineeringmaterials,wassynthesizedbyanin-situreactionmethod.Thein-situreactionsbetweenCr2AlCandFeatdifferenttemperaturesandratioswereana-lyzedbythermogravimetricanalysis-differentialthermalanalysis,X-raydiffractionandscanningelectronmicroscopy,respectively.TheeffectofsCr2AlCcontentonthebendingbehaviorswasinvestigated.TheresultsshowthatCr2AlCcanin-situreactwithFe,anddecomposetoformchromiumcarbide.Thesynthesizedcompositeexhibitsahigherflexuralstrengthandagreaterfracturetoughnessatroomtemperature.Keywords:basedcomposites;insitureaction;sintering;bendingbehaviors1IntroductionCombinewiththeuniquedesirablepropertiesofasin-glemetalorceramicmaterialandoffsettingeachother'sdeficiencies,compositescanbeusedastheengineeringmaterialsforextremeenvironmentofnuclearenergyin-dustry,miningindustry,chemicalandmetallurgicalin-dustryandsoon.[1–3]ThereinforcingceramicparticulatesincludeAl2O3,TiC,Si3N4,WC,etc..[4–8]Althoughthosetraditionalceramicreinforcementsownhighstrength,theyhavelowfracturetoughness,poorwetting,inconsis-tencyoflinearexpansioncoefficientwithiron,andarehardtobemachinedbyusingnormaltools.Recently,Cr2AlCandrelatedcompositeshaveat-tractedincreasingattention,[9–13]whichbelongtoanewtypeofternarystructuresadvanceceramicssocalledMAXphase.Comparedwithtraditionalceramicrein-forcingagents,thesekindsofceramicspossessuniquecrystallaminatedstructureasgraphite.IntheCr2AlCcrystalstructure,theCratomsandCatomsformtwocommonedgesCr6CtetrahedronwithstrongionicbondareseparatedbyAlatomicplanes,[14]andthelinkbe-tweenAlatomicplanesandCr6CtetrahedronareweakCr–Almetallicbond.[15–16]ThisstructureleadtheCr2AlCphasecombinationalpropertiesofbothmetalsandce-ramics,suchaslowdensity,highmodulus,easyma-chinability,goodelectricalandthermalconductivity,ex-cellentthermalshockandhigh-temperatureoxidationresistance,butalsocanreactwithFebythetechniqueofinsitureactionmethod,[17–19]whichisaprocesswhere2012–04–232012–09–25863(2006AA03Z527)(1983)Receiveddate:2012–04–23.Reviseddate:2012–09–25.Firstauthor:CHENXinhua(1983–),male,Ph.D.,Candidate.E-mail:[e-mail]41120131JOURNALOFTHECHINESECERAMICSOCIETYVol.41No.1January2013Cr2AlC-Fe35411reinforcementsaresynthesizedinmetallicmatrixbychemicalreactions,andensuredtheintroductionofchemicalbondingforceintheinterfaceofthereinforce-mentsandthemetalmatrix,andthehighperformancebondingwillmaketheexternalappliedstresstransferredfromthematrixtothereinforcements.Zhangetal.[20]nosedoutthatthereactionbetweenCuandTi3AlC2formTiCxandCu(Al)above950.Ourpreviouswork[21–24]showsthattheincorporationofTi3SiC2orTi3AlC2withCuincreasethestrengthandmodulusaswellaswearresistancewithoutthelossofconductivityandmeettherequirementsofapplicationsinelectricalslidingcontactsinhigh-speedrailway.Infact,similarreactionsalsoexistbetweentheCr2AlCwithFematrix.Hence,thispaperintendstoreportonprocessingandpropertyofFe-basedMetalMatrixComposites(MMCs)usingtheCr2AlC,whichisatypememberoftheMAXphaseceramics,asprecursorintherawmaterial.Byus-ingthisin-situreactionmethod,theCr2AlCceramicpar-ticlesmightdecomposetofinechromiumcarbiderein-forcingagents.Differentfromthetraditionaldirectsyn-thesismethods,thismethodhasseveraladvantages,suchasthebetterlinkbetweenthereinforcingagentswiththematrix,andtheeasierdistributedevenlyofthereinforc-ingagents,andsoon.2ExperimentalReducedironpowders(purity99.5%,size74μm,BeijingChemicalReagentCompany)andCr2AlCpow-ders(purity97%,averagesize5.197μm,thedetailscanbefoundelsewhere[10])aremixedfor10hinplasticcanstoensurehomogeneousreactantmixtures.TheCr2AlCparticlepowderssizemeasurementwasperformedonlaserdiffractionparticlesizeanalyzer(Mastersizer2000,Malvern,Britain).Then,themixedpowderswerehot-pressed(HP)at1300under30MPafor30mininflowingargongas.Theflexuralstrengthofthecompos-iteswastestedbythree-pointbendingmethodbyGB/T6569–1986,andthefracturetoughnesswastestedbysingleedgenotchedandthree-pointbendingmethod(SENB).Thefinalsampleswerecutintoblockswithdi-mensionsof3mm×4mm×36mmforbendingtests,of4mm×6mm×36mmforSENBtests,thebothtestswereperformedonauniversaltestingmachine(ZWICK,Z005)ataloadingspeedof0.5mm/min.Accordingtothestandardforceanddisplacementfromtheuniversaltestingmachine,thebendingstrengthandfracturetoughnessofthecompos-itesarecalculatedfromfollowingequationsrespectively:tr232FLRbh=(1)IC22342343(1.933.07214.5325.0725.80)FLaKabhhaaahhh=×−+−+(2)whereRtrandKICaretheflexuralstrengthandfracturetoughnessofthecompositesrespectively,Fistheforcerequiredtothefracture,Listhedistancebetweenthefulcrums,bandharethewidthandthicknessofthesam-plesrespectively,aisthecracklengthofthecomposites,hereis2.8mm.Afterthebendingtests,