简介:Thispaperstudiesthechemicalcomposition,tensileproperties,inclusions,metallogrophicstructure,andothersuchparameterstoidentifythecausesofcrackingduringthebendingofhigh-strengthsteel.Theresultsshowthatthemajorcausesofcrackingaretheoriginaltransversecracksorholesonthesurfaceoftheslabandthepresenceofscalesrolledintothecracksorholes.Coldfracturingfromsuchdefectsisrare,andcanbeeleminatedbyenhancingthecontrolofthesteelmakingprocessandbymechanicalclean-upofthesurfacecracksandholesintheslab.
简介:Thechargingpatternmayaffectblastfurnacepermeability,cokeratio,andthefreedomtoselectlow-graderawmaterials.Ore-cokemixedchargingisapotentialtechniqueforoptimizingthechargingpattern.Inrecentyears,chargingsmall-sizedcoke(nutcoke)intotheburdenlayerhasbeenappliedtosaverawmaterialsanddecreasecost.Althoughmixedcharging,especiallyaddingnutcokeintotheburdenlayer,mayhavemanyadvantages,themechanismsandsideeffectsofnutcokeusearenotwellunderstood,andthemixingratioisstilllimitedinindustrialblastfurnaceoperation.Inthisstudy,thestatusofmixedcharging,especiallynutcokeusedinblastfurnaces,wasinvestigated.Acoldflowmodelwasestablishedtostudythepermeabilityofthepackedbedintheblastfurnace"dryzone"underdifferentconditionswiththeaimofbetterunderstandingthemechanismsofmixingcokeandnutcokeintotheburdenlayer.Theeffectofcokesize,mixingcokeratio,layernumbers,andgasflowrateonthepressuredropofthepackedbedwasinvestigated.Theexperimentalresultsshowthatmixingthenutcokeintheorelayersdecreasesthepressuredroptodifferentextentsdependingonmixingratio.
简介:ThisstudyinvestigatedthevolatilizationkineticsofleadinpelletsmadeofZn-Pb-bearingdustsmixedwithcoalpowder,inanitrogenatmosphereandinthetemperaturerangebetween1100℃-1300℃,andshowedthatthereductiontemperaturehasasignificanteffectonthevolatilizationrateofleadandthatneithertheparticlesizeofthecoalpowdernortheextracarboncontenthasanyeffectonthevolatilizationrate.Theobtainedactivationenergyforthevolatilizationofleadis88.74kJ/mol.Thevolatilizationrateofleadiscontrolledbyboththeleadevaporationreactionandthediffusionofgaseousleadthroughthegasboundarylayercoveringthesurfaceofthereducedliquidlead.
简介:Sm0.2Ce0.8O1.9(SDC)electrolytewaspreparedbyamodifiedsolidstatemethodatrelativelylowsinteringtemperatureswithoutanysinteringpromoters.ThephasecompositionandmicrostructureoftheelectrolyteswereinvestigatedbyX-raydiffraction(XRD)andfieldemissionscanningelectronmicroscopy(FESEM)technologies.ArelativedensityofSDCelectrolytesinteredat1300oCreached97.3%andthemeanSDCgrainsizewasabout770nm.Theirionicconductivityandthermalexpansioncoefficientwerealsomeasuredbyelectrochemicalworkstationanddilatometer.Theelectrolyteattainedahighconductivityof5×10–2S/cmat800oCwithanactivationenergyof1.03eVandaproperthermalexpansioncoefficientof12.6×10–6K–1.
简介:Semi-solidAl2Y/AZ91magnesiummatrixcompositesslurrywaspreparedbyultrasonicvibration,effectofultrasonicvibrationtemperatureandtimeonmicrostructureofsemi-solidslurrywasinvestigated.Theresultsshowedthatwiththeultrasonicvibrationtemperaturedecreasingthesolidvolumefractionofsemi-solidslurryincreased.Thebestultrasonicvibrationtemperaturewas600oC.Withtheincreaseofultrasonicvibrationtime,theaveragegraindiameterofprimaryа-Mgparticlesdecreasedfirstly,thenincreased,theaverageshapefactorincreasedgraduallyanddecreasedslightlyafter90s,andafewrosettedendriteswereobservedafter120s.Thebestsemi-solidslurrywithaveragegraindiameterof75μmandshapefactorof0.7weregainedafterthemeltwastreatedbyultrasonicvibrationforabout60satnearliquidustemperature(600oC).Atlast,themicrostructureevolutionmechanismofsemi-solidmagnesiummatrixcompositesslurrywasanalyzedbythetheoriesofthermodynamicsandkinetics.