简介:ThemechanicalpropertiesofpressurelesssinteringFe-Si3N4bondedSiCandSi3N4bondedSiCwithsamemanufactureprocesshavebeencomparedinthispaper.TheoxidizingmechanismofFe-Si3N4bondedSiCceramicmatrixcompositehasbeeninvestigatedespeciallythroughTG-DSC(thermogravimetricanalysis-differentialscanningcalorimeter)experiment.DuringoxidationprocedurethemainreactionistheoxidationofSiCandSi3N4,SiO2whichformprotectingfilmtopreventfurtheroxidizing.AndresidualironinthesamplesbecomeFe2O3andFe3O4,theoxidationkineticsat1100~1300℃ofre-Si3N4bondedSiChasbeenstudiedespecially.Theweightgainperunitareaatinitialstagechangesaccordingtobeelinerule,inthemiddleaccordingtoconic,andinthelastoxidationperiodfollowsparabolarule.
简介:TheinfluencesoffourkindsofadditivesaddedintothematrixofMgO-Al2O3unbunedproductswereinvestigated,TheresultsshowthatsampleswithproperMgO/Al2O3rationandproperadditionofCr2O3(2%-4%)havegoodthermalshockresistanceandslagcorrosionresistanceaswell,XRDandSEMdeterminationresultsindicatethatakindofcompoundspinel(Mg,Al,Cr)O4wasformedandthemicrostuctureofthesamplesaredenser.
简介:TiN-Al2O3compositepowderswithdifferentTiNcontents(0,10vol%,20vol%,30vol%and40vol%)werepreparedwithmicrometerTiNandα-Al2O3powder(theirpuritieswere99%)asstartingmaterialsbywetballmillingfor5h.TiN-Al2O3compositewerethenpreparedbypressingtheabovecompositepowders,dryingat200℃for12handfiringat1800℃for3hinnitrogenatmosphereinhot-pressingfurnace.TheinfluencesofTiNcontentonmechanicalpropertiesandelectricalconductivityofTiN-Al2O3compositeswerestudied.TheresultsshowedthatthemechanicalpropertiesofthecompositeincreasedwithTiNcontentincreasing,whiletheresistivityofcompositesdecreased.Acompositewith40%TiNhad498MPabendingstrength,4.285MPa·m1/2fracturetoughness,1.34×10-3Ω·cmresistivity.TheSEManalysisshowedthatthefineTiNcrystalsdistributedamongthecrystalboundaryofAl2O3matrix.Theybondedtogetherforminganet-likestructurewhichplayedaroleofrestrainingAl2O3grainsfromgrowingup,tougheningandstrengthening,sothemechanicalpropertiesofTiN-Al2O3compositewereenhanced.
简介:DenseSi3N4BNcompositeceramicswerefabricatedbysparkplasmasinteringat1500,1600and1650℃under50MPafor5minusingSi3N4andBNpowdersasstartingmaterialsand2mass%Al2O3and6mass%Y2O3assinteringadditives.ThevolumefractionofBNinSi3N4BNcompositepowderswaschosenas10%,20%,and30%,respectively.TheresultsofXRDandSEMshowthatα-Si3N4completelyturnsintoβ-Si3N4whenthecompositeceramicsaresinteredat1650℃;theadditionofBNhindersthegrowthofSi3N4grains,refiningthestructure;VickershardnessandfracturetoughnessofthecompositeceramicsdecreasewiththeincreaseofBNcontent.
简介:TheinfluenceofthreedifferentAl2O3powderonself-flowingaluminacastablewasstudied.MaximumcompactionofsamplewascomputedbyAndresenEquation.TheresultshowedthattheAl2O3powder,whichhasmuchsmallerparticlesize,couldimprovethemicrostructureandthemechanicalpropertiesofcastableunderroomtemperatureandhightemperature.Withthesamepowdersize,theroomtemperaturestrengthofthecastableaddedwithAl2O3powderproPertiesofwhichwerealteredbyaddingmineralizingagent,washigherthanthatofthecastableaddedwithcommonAl2O3powder,buttheflowabilityofthesethreedifferentcastablewasalmostthesame.
简介:Thestabilizationofγ-aluminiumoxyni-tridespinel(γ-AlON)hasbeeninvestigatedbyadditionofMgO,MgAl2O4,etc.,inreactionprocess.Theresultsindicatedthattherearewidersolidsolutionareasnear,Al2O3-richsideinAlN-Al2O3-MgOternarysystems,ThecontentofstabilizedAlONphaseinsamplesisrelatedtoheatingtemperatures,additives,etc.ThelatticeparametersoftheirAlONphasescouldbewelldescribedbytheequation:a0=0.7900+0.0375[MgO]+0.015[AlN](nm)
简介:Thespecimenswerepreparedbymoldingthemixtureofsilicafume(w(SiO2)=94.5%;averageparticlesize:0.08μm)andsiliconnitride(≤0.074mm)withamassratioof11,carbonembeddedfiringat1300℃,1450℃,1500℃,1550℃and1600℃for3hinair,andthenwater-cooling,respectively.Themicrostructureandphasecompositionofthespecimenswereanalyzed.Theresultsshowthat:(1)silicafumereactsobviouslywithSi3N4formingSi2N2Oabove1550℃.TheedgesandcornersofSi3N4grainsbecomesmoothandtheSi3N4grainsdistributeinthecontinuouscementationphaseofSi2N2OformingthedensestructureofSi2N2OpackedSi3N4;(2)below1500℃,theedgesandcornersofSi3N4grainsareclear,Si2N2Odoesn'tform,andonlySiO2crystallizesfromsilicafumewhichhappensobviouslyat1300℃.
简介:Researchonnewtypesofcastables,pre-castassemblypartsandthermalinsulationmaterialswithgoodresistancetowear,thermalshockanderosion,andlowthermalconductivity,wasdonetosolveproblemsofhighsystemenergyconsumption,crackingandspallingofpartialliningandmismatchoffurnacetopmaterialandhangingmaterialandsoon,causedbyunreasonabledesignofChina'sAl(OH)3dilutephasefluidizedbedroastingfurnacelining.Severaldifficultproblemssuchasthematchingofdifferentmaterials,preservationofexpansionjointsamongdifferentzonesandreasonablemechanicaldistributionofliningweresolved.'Integratedfurnace'conceptwasestablishedincludingrefractoriesR&D,liningstructuredesign,constructionoptimization,furnacewarmingtechnology,initialoperationandliningmaintenancetechnology.Thekeytechnologiesofhigh-efficiencyandenergy-savingforfurnacesweredeveloped.TheseachievementshavebeenappliedtoChina'sAl(OH)3dilutephasefluidizedbedroastingfurnacestoreduceenergyconsumptionby1000MJpertonalumina,enhancethecapacityandreducetheexhaustgasemission.
简介:Inordertoimprovetheservicelifeofcorundumliningforinductionfurnace,corundumdryrammingmixwaspreparedusingbrowncorundum,fusedmagnesia,andα-Al2O3micropowderasmainstartingmaterials,andtheinfluenceofα-Al2O3micropowderadditions(0,1%,2%,and3%,inmass)onpropertiesofcorundumdryrammingmixwasinvestigated.Theresultsshowthatafterheattreatingat1600℃,withtheincreaseofα-Al2O3addition,thepermanentchangeindimensionsonheatingofthespecimensdecreasesfirstlyandthenincreases,bulkdensityincreases,apparentporositydecreases,andthecrushingstrengthdeclinesfirstlyandthenenhances;whentheadditionofα-Al2O3is2mass%,thepermanentchangeindimensionsonheatingofthespecimensisrelativelysmallandthecrushingstrengthdecreasesto22.8MPa.TheXRDandSEMresultsshowthatafterfiringat1600℃for3hsmallgranularmagnesiumaluminatespinelformsandiswelldistributed,whichenhancesthedensity.
简介:TheAl2O3-SiCcompositepowderswerepreparedinargonatmosphereusingcoalgangueandcarbonaceousmaterials
简介:Simplethree-pointbendingtestatambienttemperaturecharacterizedthemechanicalbehaviorofburnedAl2O3-Crefractoriesbeforeandafterthermalshockinassociationwiththeprocessingparameters(graphitecontentandcokingtemperature,etc.).Theresultsshowedthatnon-linearplastic-elasticbehaviorunderloadlowerthancoldmodulusofrupture(CMOR)wasregisteredinallspecimensandreallinearelasticbehaviorcouldbeidentifiedafterthefirstload.Thetotaldeformationcouldbedividedintotwoparts,plasticandelasticareas.ThegraphitecontentandjointbondingsystemofcarbonandceramicphaseswereresponsibleformechanicalbehaviorofAl2O3-Crefractories.
简介:TheeffectoftheadmixturesofAlandSimetalsandB4CandMgAlONcompoundsontheoxidationofMgO/Si3N4compositerefractoryhasbeenstudied,whichisapromisingcarbonfreerefractoryforsteel-makingapplicatlon.Thefourkindsofadmixturescanbeusedasanti-oxidantsforSi3N4,butthemixtureofAlandSiachievedthebestresult.Themixturecannotonlyplaytheroleasantioxidant,butalsoassistthesinteringprocessandhelpformdensesinteringlayer,improvingthepropertyofthecomposite.
简介:UsingAl2O3-MgOcastableinlargeladlecanavoidcontainationofmoltensteelfromcarbon-containingrefractoriesandincreasladleservicliferemarkably,Theadditionofmagnesiaandfinepowder,theeffectofgrainsizeontheproper-tiesofthecastable,especiallylinearchangeandstructurespallinghavebeenstudied,Castablepro-duedforlargeladlewithsmallweareratehasgotgoodapplicatioresult.