简介:Precipitationstrengtheningaswellassolutionstrengtheningiskeymechanismforheatresistantsteels.Itisveryimportanttocharacterizetheprecipitatesin9%Crferriteheatresistantsteels,especiallytoshowthenanometer-sizedparticles.Bytransmissionelectronicmicroscopeattachedwithanenergydispersivespectrometeraswellasopticalmicroscope,scanningelectronicmicroscope,themicrostructureandchemicalcompositionofprecipitatesina9%Crheatresistantsteelafterdifferentheattreatmentswereinvestigated.ItwasfoundthatthemicrostructureofnormalizedsamplewasmartensitewithfineNbCandFe3C.Themicrostructureoftemperedsampleistemperedmartensite,andtheremainlyweretwotypesofprecipitates,M23C6withthesizerangeof50-300nmandMXwiththesizeof10-100nm.SuperfineM23C6precipitatedpreferablyonpriorausteniticgrainboundariesandmartensiticlathboundaries,whilenanometer-sizedMXprecipitatesweredistributedrandomly.Aftershort-termcreep,Lavesphaseformedalonggrainboundariesofthe9%Crsteel,andM23C6andMXprecipitateswerefoundtobecomecoarser.Moreinformationaboutprecipitatesinthe9%Crsteelhadbeenexhibitedbyatomicforcemicroscopy.Thereby,distribution,sizeandshapeoftheprecipitatesaswellastheircompositionsandstructureswererevealed.
简介:TheextractionofCe(Ⅳ)inH2SO4/H3PO4systemwasinvestigatedsystematicallyusingbifunctionalionicliquidextractants(Bif-ILES)[A336][P507],[A336][P204]and[A336][C272]inn-heptane.TheeffectsofH2SO4concentration,extractantconcentrationandsalting-outagentconcentrationwereobservedindetail.TheextractionmechanismofCe(Ⅳ)inH2SO4/H3PO4systemwasobtained.ThecomparisonwithotherextractantssuchasCyanex923,TBPwasalsostudied.Thermodynamicfunctionsoftheextractionreactionwerecalculated,showingthattheextractionwasanexothermicprocess.TheseparationofCe(Ⅳ)fromRE(Ⅲ)andTh(Ⅳ)wasalsoinvestigated.TheresultindicatedthatCe(Ⅳ)couldbeselectivelyextractedinthissystem.CePO4nanoparticleswereobtainedintheprocessofstrippingusingH2O2inH2SO4/H3PO4system.X-raydiffraction(XRD),scanningelectronmicroscopy(SEM)andspectroscopywereadoptedforthecharacterizationofthesample.
简介:ThisstudyresearchestheeffectsoftherefiningtreatmentonthemicrostructureandthemechanicalpropertiesofH13mandrelsteelandcomparestheseeffectswiththoseoftheconventionaltreatment.Theresultsindicatethatbothcarbideparticlesandgrainswererefined,carbideparticleswereuniformlydistributedbytherefiningtreatment,andtherefore,thestrengthandtoughnessofH13mandrelsteelwereimproved.Rapidcoolingafterthesolutiontreatmentmayinhibitintra-granularprecipitationofcarbideparticles,whichisfavorabletoenhancingtoughness.Consequently,high-performanceH13mandrelsteelcanbeproducedbyproperrefiningtreatment.
简介:Thedifferencesofreductionbehaviorsbetweenironorelumpandpelletswerestudiedbyconductinglowtemperaturereductiondegradation,staticloadreductionanddroplettests.Thesetestssimulatedtheconditionsofreductiontemperatureandhydrogen-containinggasinCOREX.Duetoitsdensestructureandlowporositycomparedwithpellets,lumporepossessespoorreductiondegradationindex(RDI)andslowerreductionrateinearlyandmediumreactionstages,showingsignsoflowerstrength,lowersofteningandmeltingtemperatures,aswellasawidermeltingzoneandhigherΔP.Thatprovidessomebasistoexplainthephenomenaofdifferentialpressurerise,metallizationdeclineandmorestickingaftertheusageoflumporeinCOREXplant.
简介:Opticalmicroscope,stereomicroscope,scanningelectronicmicroscope(SEM)andmechanicalpropertytestingwereusedtoresearchtheeffectsofdifferentquenchingtemperaturesonthemicrostructureandmechanicalpropertiesoftheH13mandrelsteel.Theresultsindicatethatfollowinganincreaseinthequenching,thedegreeofalloyingisenhancedduetothecarbidesdissolvinggraduallyinaustenite,whichimprovesthehardenabilityofthespecimens,aswellastheirroomandhigh-temperaturestrength.Atthesametime,thefracturetoughnessincreasesduetotheincrementofthemartensitenumberandtheinterparticledistanceofthecarbides.However,extremelycoarsegrainandmartensitecandecreasetheimpacttoughness.Optimalperformancecanbeobtainedafterquenchingat1060℃anddoubletemperingat620℃.Consequently,theservicelifeoftheH13mandrelsteelisextendedsignificantly.
简介:通过对耐大气腐蚀钢SPA—H的成分设计、冶炼过程及轧制过程的控制,生产出尺寸公差、表面质量及各项性能都符合JISG3125—1987标准要求的SPA—H钢带。
简介:Inthiswork,boththethermalexpansionandelectricalconductivityofnanocrystallineLa2Mo2O9werestudied.ThenanocrystallinepowderofLa2Mo2O9wasobtainedbysol-gelmethod,andwiththehelpofSHP(superhighpressure)upto4.5×104atmat700℃forashorttime,andthenanocrystallinepowderwasdensifiedwithoutobviousparticlesizegrowth.TheelectricalconductivityofnanocrystallineLa2Mo2O9wasoneorderofmagnitudelowerthanthatofthemicrocrystallinesampleatthesametemperature.Owingtothephasetransition,themicrocrystallineLa2Mo2O9hasanabruptincreaseofthermalexpansionwithapeakvalueof48×10-6K-1at556℃.Forthenanocrystallinematerial,thepeakvalueincreasesto112×10-6K-1at520℃.Ontheotherhand,above600℃thesignificantgrowthofparticlesizeofthenanocrystallineLa2Mo2O9wasobserved,accompanyingbyatremendousincreaseofthermalexpansionwithapeakvalueofthirdhigherthanthatofLa2Mo2O9.