简介:采用金相组织观察、力学性能测试和统计分析等手段,研究了成品退火工艺对Φ5mmTP2内螺纹铜管微观组织和力学性能影响规律。结果表明:Φ5mmTP2内螺纹铜管退火温度为470~480℃时,铜管组织细小、均匀,同时能获得较高塑性和较高强度;490~500℃时,铜管晶粒尺寸、力学性能波动大;510~520℃时,铜管组织易粗大。Φ5mmTP2内螺纹铜管在470℃退火时,晶粒尺寸随退火时间的规律变化为d=0.0008t3-0.062t^2+1.7t-1.3,保温21min时,铜管再结晶基本完成,保温时间为28~31min时,铜管组织状态和综合力学性能最佳。
简介:Praseodymium(Pr)wasimpregnatedtoCeO2-ZrO2solidsolutionbyanimpregnationmethod.Theas-obtainedPrmodifiedCeO2-ZrO2wasimpregnatedwith1wt.%Pdtopreparethecatalysts.ThestructureandreducibilityofthefreshandhydrothermallyagedcatalystswerecharacterizedbyX-raydiffraction(XRD),Raman,X-rayphotoelectronspectroscopy(XPS),COchemisorptionandH2temperature-programmedreduction(H2-TPR).Theoxygenstoragecapacity(OSC)wasevaluatedwithCOservingasprobegas.EffectsofimpregnatedPronthestructureandoxygenstoragecapacityofcatalystswereinvestigated.TheresultsshowedthattheagedPr-impregnatedsampleshadmuchhigherOSCandbetterreducibilitythantheunmodifiedones.TheschemeofstructuralevolutionsofthecatalystswithandwithoutPrwasalsoestablished.PartialoftheimpregnatedPrdiffusedintothebulkofCeO2-ZrO2duringageing,whichinhibitedthesintering,andincreasedtheamountofoxygenvacanciesinCeO2-ZrO2support.Furthermore,thoseimpregnatedPrspecieswhichcoveredonthesurfaceofthesupportobstructedthestrongmetal-supportinteractionbetweenPdandCesoastoreducetheencapsulationofPdaswellasthebackspill-overoftheoxygenduringthecatalyticprocess.
简介:TwonovelwashcoatsCe0.8Zr0.15La0.05OδandCe0.8Zr0.2O2waspreparedbyanimpregnationmethod,whichactedasahostfortheactivePdcomponenttopreparePd/Ce0.8Zr0.15La0.05Oδ/substrateandPd/Ce0.8Zr0.2O2/substratemonolithiccatalystsfortoluenecombustion.ThewashcoatswascharacterizedbyX-raydiffraction(XRD),Ramanspectroscopy,Brunauner-Emmett-Teller(BET),andH2-temperature-programmedreduction(H2-TPR).Theresultindicatedthatboththewashcoatshadstrongvibration-shockresistanceaccordingtoultrasonictest.DopingLa3+intoCeO2-ZrO2solidsolutioncouldgeneratemoreoxygenvacancies,andcouldinhibitthesinterofCeO2-ZrO2solidsolutionwhencalcinedathightemperatures(800,900and1000°C).ThewashcoatCe0.8Zr0.15La0.05Oδhadmuchbetterredoxproperties.ThereductivetemperatureofCe4+speciesshiftedtolowtemperatureby60°Cwhenthewashcoatscalcinedathightemperatures(800,900and1000°C).ThePd/Ce0.8Zr0.15La0.05Oδ/substratemonolithiccatalystcalcinationat500°Chadthebestcatalyticactivityandthe95%tolueneconversionatatemperatureaslowas190°C.Whencalcinedatlowtemperature(500and700°C),thecatalyticactivityhaslittleimprovement,however,whencalcinedathightemperature,thecatalyticactivityofPd/Ce0.8Zr0.15La0.05Oδ/substratemonolithiccatalystshadsignificantimprovement.Ascatalystwashcoat,theCe0.8Zr0.15La0.05OδhadbetterthermalstabilitythanthewashcoatCe0.8Zr0.2O2,thedevelopedPd/Ce0.8Zr0.15La0.05Oδ/substratemonolithiccatalystinthisworkwaspromisingforeliminatingVolatileorganiccompounds.