简介:TheCW-CO2laserdrivengasreactionwasappliedtopreparenano-sizedSiCpowder,SiH4andC2H4ofhighpurties,asstartingmaterials,weremixedtacertainrationandintroducedintotheresactioncell.Thegasesflewacrossthelaserbeamorthogonallyandthuswereheatedbylaserbeam.Thenano-sizedSiCultrafinepowderwswereformedthroughthermicgasreation.Thefinalproductivityofthisprocesswas97%,Theobtainedpowderswerecharacterizedandanalyzed.ChemicalanalysisrevealedthattheSiCcontentwas95.38wt%,Oxygen,theprimaryimpurity,weighted1.32%whiletraceimpurities,suchascalcium,magnesiumandothermetals,wereonly0.03%,XRD,XPSandTEMindicatedthatthpowderparticleswerenearlysphericalandnotagglomerated.Theparticlesizerangedfrom10nmto25nmwithanaverageof15nm,Theparticlestredtobenoncrystalline.
简介:Lowcement(LC)andultra-lowcement(ULC)bauxite-SiCcastablesareimportantandhighperformancemonolithicrefiactoriesandtheyhavebeenwidelyusediniron-makingandincineratorlinings.Inthiswork,rheo-logicalbehaviorofLCandULCbauxite-basedSiC-contain-ingcastableshasbeenstudied,includingtheeffectsofSiCcontentandcementcontentonrheologicalpropertiesofthecastables.TheresultsshowthatwithanincreaseofSiCandcementcontent,rheologicalpropertiesofthecastablesdeteriorate.Ontheotherhand,moderateamountsofSiC(4%~8%)andofcalciumaluminatecement(2%~4%)haveveryslightinfluenceonrheologicalproperties,(i.e.whenthecastablesareshearedtheirtorqueandyieldtorqueonlyslightlyincreasewiththeshearingspeed).Therheologicalcharacteristicsofthecastablesfol-lowBinghamfiuidandalwaysshowshearthinningbehav-ior.
简介:ThemechanicalpropertiesofpressurelesssinteringFe-Si3N4bondedSiCandSi3N4bondedSiCwithsamemanufactureprocesshavebeencomparedinthispaper.TheoxidizingmechanismofFe-Si3N4bondedSiCceramicmatrixcompositehasbeeninvestigatedespeciallythroughTG-DSC(thermogravimetricanalysis-differentialscanningcalorimeter)experiment.DuringoxidationprocedurethemainreactionistheoxidationofSiCandSi3N4,SiO2whichformprotectingfilmtopreventfurtheroxidizing.AndresidualironinthesamplesbecomeFe2O3andFe3O4,theoxidationkineticsat1100~1300℃ofre-Si3N4bondedSiChasbeenstudiedespecially.Theweightgainperunitareaatinitialstagechangesaccordingtobeelinerule,inthemiddleaccordingtoconic,andinthelastoxidationperiodfollowsparabolarule.
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:MicrostructureandgrainboundarycharacterofhotpressedbinaryAl2O3(mullite,ZrO2)-SiCompositesandquaternaryAl2O3-mullite-ZrO2-SiCcompositewerestudiedbyelectronmicroscopyandmicroanalysis,ResultssuggestthatthereexistgrainboundarysolidsolutionsduetoelementaldiffusionnearSiCandmatrixoxidesgrainboundaries.