简介:ThisworkstudiedthecharacteristicsofSiO2distributionandstructureofsilicatephasesinMgO-ZrO2compositessynthesizedbyrawmaterialsoflightfiredmagnesitendzircon,Theresultsindicatethat30wt%-40wt%SiO2contentinthesystemisexistedintheformofcrystallineofforsterite(M2S),theremainderingofSiOcontent(60wt%0-70wt%)isexistedintheglassphase,Thechemicalcompositionofglassphaseiswellagreedwiththechemicalcompositionofmonticellite(CMS).
简介:β-sialon/alumina/silicamixturesweresinteredinflowingnitrogenat1500℃and1600℃respectively.ThesinteringpropertiesandmorphologyofsampleswereinvestigatedbySEM,EDSandXRD.Resultsshowthatsinteredpropertiesofthesamplesareinfluencedbysoakingtemperaturesandcompositions.Bulkdensitiesofsamplesareincreasedwiththeincreaseofthesoakingtemperature,whereastheapparentporositiesaredecreased.Masslossofthesinteredsamplesat1500℃islowerthanthatat1600℃,butallthemasslossremainsapproximatelyconstantwiththeincreaseofsialoncontent.Fromthepointofthermodynamicanalysis,ComplexchemicalreactionstakeplaceinsamplesduringsinteringprocessandthevolatileofSiO(g)isresponsibleforthemasslossofsamples.Comparedtocrosssectionmicrostructureofβ-sialon/Al2O3/SiO2mixturessinteredincokepowderbedconsistingofthedensecenterwithwell-developedcolumnofsialonphase,thetransitionalpartwithneedlelikegrainnitrogen-containingphaseandtheloosepartwithshortgranularAl2O3phase,thoseofmixturessinteredinflowingnitrogenisofwell-developedsialonindensecenterandslightlyloosepartwithsialondebris.
简介:IntheprocessofsynthesisofnanometerSiCprecursorswithsol-gelofSiO2andlignin,theproductsofallsizesrequiredcanbecontrolledbytheconcentrationofreac-tants,pH,temperature,ractionandageingtime,andsoon.Thebestconditionsinthisreserchare:theconcentrationofNa2SiO3andorganicmattersare4.50%and26.4%respectively,pH=3.3,T=65℃,ageingtimeis30min,driedat150℃,thesizeofSiCprecursorsisabout2.0μm。
简介:LowcementAl2O3-SiO2castableswaspreparedusingsupergradebauxite(w(Al2O3)>85%)asaggregate,brownfusedcorundum,siliconcarbide,Secar71CAcement,α-Al2O3micropowderandmicrosilicaasfinepowders.TheinfluenceofSiC(0,5wt%,10wt%,and15wt%)onresistancetoPbO-richslagwasinvestigatedbystaticcrucibleslagtest(1300℃for5h,inair).TheslagcorrosionmechanismofthecastableswasanalyzedbymeansofSEM,EDSandXRD.TheresultsshowthattheresistanceofAl2O3-SiO2castablestoPbO-richslagisimprovedobviouslybytheadditionofSiC.ThecorrosionmechanismofthePbO-richslagcanbediscribedasthatPbOintheslagreactswithSiO2andCaOinAl2O3-SiO2castables,forminglow-meltingcompounds(suchasPbO·SiO2and2PbO·SiO2).
简介:InordertoimprovethemechanicalpropertiesofSiO2aerogel-glassfibercomposites,effectsofdifferentsolvents(cyclohexane,n-hexane,ethanol,acetone)anddifferentdispersingmodes(planetaryballmilling,ultrasonicdispersionandmechanicalstirring)anddispersingduration(10-40min)onthedispersionofchoppedalkali-freeglassfiberbundleswerestudiedtodeterminethebestdispersionprocess.Onthisbasis,thematerialswerebatchedaccordingtothemassfractionofSiO2aerogelpowdertochoppedalkalifreeglassfiberbundlesof90:10,andacertainamountofzincoxidelight-screeningagentandphenolicresinbinderwereadded.SiO2aerogelglassfibercompositespecimenswerepreparedbydirectaddingchoppedalkalifreeglassfiberbundlesandpre-dispersedchoppedalkalifreeglassfiberbundles,respectively.Thecoldcrushingstrengthandthethermalconductivityatdifferentsurfacetemperatures(300,400,500and600℃,respectively)ofthespecimensweremeasured.Theresultsshowthat:(1)theoptimumdispersionprocessofchoppedalkali-freeglassfiberbundlesisusingethanolassolventandmechanicalstirringfor30min;(2)pre-dispersionofchoppedalkali-freeglassfiberbundleshaslittleeffectonthethermalconductivityofSiO2aerogel-glassfibercompositesbutcanimprovethecoldcrushingstrength.
简介:Thisworkinvestigatedthethermo-gravimetric(TG)changeandexplosionresistanceofultra-lowcementAl2O3-SiO2castablesaddedwith0,5%,10%,15%and20%of≤74μmrawbauxitepowderscontaining72.8%Al2O3,respectively.Thecastableswerepreparedusingwhitefusedaluminaasaggregate,powdersofwhitefusedalumina,fusedmullite,α-Al2O3ultrafines,3%CAcementand5%microsilicaasthematrixportion.TGchangeofthecastableswasinvestigatedbyathermo-gravimetricanalyzerforlargesizespecimen.Whentherawbauxiteadditionislessthan10%,themass-losingbehaviorofthecastablesissimilartothatwithoutrawbauxite,tendingtoreachaconstantmassaround400℃,beforewhichthemass-lossismildandproducinglittledestructiveinfluence.Withmorethan10%rawbauxiteaddition,however,themass-lossincreasessignificantly,andthetemperaturetoreachaconstantmassincreasesto600℃orhigher,unfavorabletostructuralstabilization.Withtherawbauxiteadditionupto20%,nonegativeinfluenceonexplosionresistanceisfound.
简介:AnO'-Sialon-Al2O3compositerefractorywaspreparedbyinsitureactionofSi3N4-ZrSiO4-Al2O3mixturewithfusedaluminaaggregates.Densification,insitureactionprocedureandmicrostructureofthematerialwereinvestigatedbymeansofX-raydiffraction,opticalandscanningelectronicmicroscopesandEDAX.