简介:Cr2O3canbesinteredwellat1500℃incarbon-embeddedconditionorH2atmosphere.Butthehighchromebearingrefractoriescannotreachdensificationwhensinteredat1700℃for10hinweakreducingatmosphereformedbythecombustionoffuel,anditsapparentporosityisabout18%.Thehighchromebearingrefractoriesaremainlyusedincoalgasifiers.Thetemperatureinthefurnaceisabout1500℃andtheproductsareH2andCO,whicharejustthesinteringconditionsofthedensechromerefractorieswithapparentporositylessthan10%.Thehighchromebearingrefractoriesusedincoalgasifiersmaybesinteredagainandthenshrink,destroyingthegasifierlining.Thethermodynamiccalculationshowsthatitissafeaboutthehighchromebearingrefractoriesusedingasifiers.Itisalsoexplainedthatthehighchromebearingrefractoriescan’tbesintereddenselyinweakreducingatmosphereformedbythecombustionoffuel.Thenewsinteringtechnologiescanbeusedtoimprovethebulkdensityofthehighchromebearingrefractories.
简介:Inthisstudy,inordertoevaluatetheperformanceofhomogenizedbauxite,twoAl_2O_3-SiC-Ccastableswerepreparedusinghomogenizedbauxiteandbrownfusedcorundumasaggregates,respectively.5mass%andalusitewasintroducedintothetwocastablessoastoresearchtheeffectandmechanismofandalusiteinAl_2O_3-SiC-Ccastables.Theresultsshowedthat:(1)comparedwiththebrownfusedcorundumbasedcastables,thehomogenizedbauxitebasedcastableshadhighercoldstrengthafterheattreatment,butlowerhotmodulusofrupture;(2)additionof5mass%andalusitecouldenhancethecoldandhotmodulusofrupture,improvethethermalshockresistance,andoptimizethemicrostructureofspecimens;(3)themullitizationofandalusitewasnotobviousinthecastablesfiredat1100-1400℃.
简介:Inthispaper,X-raydiffractogramanalysisandSEMobservationofAl4C3formedathightemperaturefromcarbon-containingrefractorieswithAlhavebeencarriedout.Aluminumaddedtocarbon-containingrefractoriesreactswithC(s)toformAl4C3(s)graduallyduringheatingfrom600℃to1200℃.ItisconsideredthattheinterlockedstructureofAl4C3platecrystalspromotestheoutstandingincreaseofhotmodulusofruptureofcarbon-containingrefractorieswithAl.TheHMORofcarbon-containingrefractoriesaddedwithAladditivefrom0to5wt%increasesby2.8timesbeingfrom6.5MPato18.2MPa.AfterathermochemicalcalculationforhydrationreactionprocessesofAl4C3andH2O(g),theequilibriumpartialpressurechartofH2O(g)inH2O-Al4C3-Al(OH)3systemvsvarioustemperatureshasbeenattained.TheH2O(g)partialpressureintheairneededfortheAl4C3hydrationreactionisnomorethan10~18atmatthetemperaturebelow120℃.Itisconsideredthattheburnedcarbon-containingrefractorieswithAlisextremelyeasytohydrateandthecrackingofburnedcarbon-containingrefractoriesisgeneratedbecausethatthehydrationexpansionis2.11timesduringtransformingfromAl4C3toAl(OH)3.ThefundamentalmeasureagainsthydrationoftherefractoriesistoinsulatetherefractoriesfromH2O(g)byvariousmeanssuchaspitchimpregnationorothersealingmaterials.
简介:ThispapertestifiesthataluminiumandsiliconaswellastheircarbidexandnitridescanreactwithCOincarbon-containingzonetoformAl2O3andSiOgasthroughexperimentandthermodyanmicanalysis,ThegasesdiffusetooxidizedzoneandreactwithoxidizerssuchasCO2,Asaresult,Al2O3andSiO2aredepositedfromthegases,wihichblockthepores,thusreducetheamountofgasdiffusionandincreaseoxidationresistnaceofcarbon-containingmaterials.