简介:Hexagonplate-likeAl8B4C7powdersweresuccessfullysynthesizedusingamixtureofdiborontrioxide,activatedcarbonandaluminumoraluminabyacarbothermalreductionprocess.TheeffectofAlsourceandstartingmaterialsadditionsonsynthesisofAl8B4C7wasinvestigated.ThephasecompositionandmicrostructureofAl8B4C7powderwerecharacterizedbymeansofXRD,SEMandEDS.ThemainphasecompositionsoftheproductssynthesizedfromAl,B2O3andactivatedcarbonareAl8B4C7andAl2OC.Al2O3canreplaceAltosynthesizeAl8B4C7.Al8B4C7grainssynthesizedfromAl2O3,B2O3andactivatedcarbonarehexagonplate-likeandhaveathicknessof10μmandasizeofabout100μm.
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:化肥生产形势自1997年第3次滑坡以来,一直处于低谷。特别是2001年12月中国加入WTO以后,化肥形势更加严峻。为了生存和发展,许多企业采取了相应的对策。从降低化肥生产成本着手,狠抓造气技术改造工作。尤其是中氮肥煤造气工序中,存在工艺流程落后,设备陈旧、余热回收不完全等诸多缺陷,因而煤耗高、气化强度低,长期影响着中氮肥生产的发展和企业的效益。近年来,个别厂对中氮肥余热回收装置和工艺流程以及设备进行了技术改造,取得了明显的经济效益。在技术改造时,重点放在应用新技术、新设备上。原化工部化肥司负责人王文善司长在2001年11月厦门全国化肥会议上指出:“中氮肥行业必须进行技术改造,不断造就是等死,改造得不好就是找死,一定要改造得好才有出路,才能生存和发展下去”。