固相含量对氧化钇稳定氧化锆性能的影响

Influncesofsolidloadinonproperites

ofyttria—stabilizedzirconia。

LIuXiao-guang,LIGu叫un,ToNGJian-feng,cHENDa-ming(NationalKeyLaboratoryofAdvancedcompositeS,BeijinglnstituteofAeronautical

Macerials?Beijing100095?china)Abstract:TheinfluencesofsolidsloadingontherheoIogicalpropertiesusedforaqueousgel—casting

werestudied,andalsointhispaperthemicrostructures,densities,

andstrengthsofyttria—stabi“zedzirconiawereinVestigated?Resultsshowthataqueousslurriesofdifferentsolidloadingsexhibitshearingthinningbehavior.Densitiesofgreenbody

increasewithincreasirlgsolids,andstrengthsdecrease.However,densitiesofsinteredbody

increasefirstlyandreachmaximumat53Vol%,thendecrease?Strengthsdecreasewithincreasingsolidloadings.

Microstructuresof53volsolidloadingaremoreuni{ormandlesspores?So53vol%iscompromisingsolidloadinginthissystem.

KeywoI?ds:solidsloading;rheologic萌properties;aqueousgel—casting;yttria。stabilized

zirconja;aqueousslurrles;poresCLCnumber:TQl74.758

1Introduction

DocumentcOde:AArticleID:l001—973l(2005)05一0767一04

Yttria—stabilizedzirconia(YSZ)isthemostwidelyusedelectrolytematerialforoxygensensorands01idox—idefueIcellsapplication.PurezirconiacannotactasagoodelectrolyteduetoitspoorionicconduchVityandphasetransformation(monoclinicandtetragonal)onheatingassociated

withalargeVolumechange.DopingofZrOzwith8m01%yttriacanstabiIizethecubicfluoritephaseand,intheprocess,increaseitsoxygenVacancy

concentration1eadingtoanenhancedionicconductivity.Thismakesstabilizedzirconiasuitableforuse

asane一

1ectrolytematerialandyttriaisthemostcommonlyuseddopantforstabilizingzirconiaforthe

aforesaidapplica—tion[1I.

Denseandfine—grainedceramicsarerequiredformanyapplications.Thecontrolofgreencompactmicro—structuresaswellastheselectionofpowderisimportant.Specifically,densegreencompactswithuniformlydistributedsmallDoressintertodenseceramics.1tisdifficulttomakedesirablecompactsbyconVentionalfabri—cationmethods[引.Thetraditionalfabricationofceramicpartsislimitedtoseveralformingproceduressuchaspressing,slipcasting,andinjectionmolding.Althougheachtechniquepossessesmerits,noneonitsownisca—pableofmeetingtoday’schallengessuchasreproducibility,reliability,andfabricability[3~5].Aqueousgelcast—ingisanearnet—shapeformingtechniqueandisbasedonideasborrowedfromtraditionalceramicprocessingandfrompolymerchemistry.ItisagenericprocesseswhichcanbecarriedoutreadilyinavailabIeequipment.Inad—dition,aqueousgelcastingisalowcostceramicfabricationtechniquethatcan

beemployedtoproduce1argeareaandthin—substrateYSZelectrolyte[¨.Thedispersionofpowdersisanimportantprocessforthepreparationofdesirablecompacts.Solidloadinghasanimportanteffectondispersionofpowdersandflowingofaqueousslur—ries.Thepresentworkaimstostudythecorrelationbetweenslurryrheology,densities,strengths,microstruc—turesandsolidloadingsofYSZaqueousslurries.

2Experimentalprocedures

Theyttria—stabilizedzirconiapowders(YSZ,99.9%purity)haveanaveragesizeof1.5肛m.Acrylamide(AM)wasusedasthemonomerandN,N—methylenebisacrylamide((C2H3CONH)2CH2,MBAM)actedasthecross—linker.N,N,N’,N’一tetramethylethylenediamine(TEMED)and(NH4)2S208wereusedascatalystandinitiatorrespectively.AcommercialproductDAproducedbyBeijinginstituteandchemicalindustrywasselect—edasthedispersants.YSZslurrieswithdifferentsolid10adingswereball—milledfor20htogiveweUdisperseda—aueous

slurries.Thentheslurriesweredeairedfor15min.Afteraddingcatalystsandinitiator,theseslurrieswerecastineitherplasticorglassm01ds.Aftergelation,theceramicpartsweredem01dedandimmediatelydriedatroomtemperature.Thenbothbinderburnoutandsinteringwerecarriedoutinairfurnace.Rheological

*Receiveddate:2004—11一03Corr髑pondingauthor:LIUXia0-guang

Bi0鬓阳phy:LIUxia0-guang,male,doctor,engineer,majorinceramicandceramicmatrixcomposites.

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