简介:TheeffectofrareearthelementyttriumonthehightemperatureoxidationresistanceofadirectionallysolidifiedNi-basesuperalloywasstudiedwithscanningelectronmicroscopy(SEM),energydispersivespectrum(EDS)andX-raydiffraction(XRD)techniques.Theresultsshowthattheoxidationresistanceofthealloyissubstantiallyimprovedbyaddingproperamountofyttrium.
简介:TheNaYF4:Yb,Ernanocrystalsweresynthesizedviathethermaldecompositionofmetaloleateprecursors.Thenanocrystalsinhexagonalstructurewerehighlyuniformandinsizeof25nm.Thebrightupconversionluminescencewasobservedundertheexcitationof980nmlaserandtheupconversionemissionspectrawereinvestigatedatdifferentpumppowers.Theemissionintensityratioofredlighttogreenlightlinearlyincreasedwithpumppowerincreasing.ThisresultindicatedthatthereexistedalargethresholdpowerofsaturationpumpforthefirstexcitationstateinNaYF4:Yb,Ernanocrystalscomparingtothatinbulkmaterial.
简介:Theeffectoftherareearthsonthehightemperaturepropertiesofdeformedleaded-brasseshasbeenstu-diedwiththehightemperaturetensiletest.Theresultsshowthattherareearthadditivescanincreaseelongationofalloysathightemperature,buttheyhadlittleeffectonthemaximumflowstress.WiththehelpofSEM.X-raydiffractioninstrument,quantitativemetallographyanalysisinstrument,etc.,theeffectoftherareearthelementsonthemierostruetureofalloyshasalsobeenexamined.
简介:Theactivatedaluminaasacatalystcarrierwerewidelyusedinautomotiveexhaustcatalystsunderhightemperature,suchas,petroleumrefiningcatalysts,hydrogenationandhydrodesulfurizationcatalystcarrierinChinaandabroad.γ-Al2O3wasthecatalystcarrierthatwasthemostwidelyusedandthebestcarrierofimprovedspecificsurfacearea.However,theactivationofthecoatingconsistedofγ-Al2O3wereusuallytransformedintoα-Al2O3at800oC,causingincreaseddensity,reducedspecificsurfacearea,andthecollapseresultofporestructure.Whilethetemperaturereached1200oC,activationofcoatingdetachedfromthecarrier,theresistanceofflowinggasincreased,catalyticactivitydecreased.AdditionofLa2O3stabilizedtheγ-Al2O3crystalstructure,whichwouldkeeptheactivationstabilityofcoatingatahightemperatureandinhibitactivityloss.Theactivatedaluminacarriertreatedwiththesolid-pore-expandingagentcontaining[La(EDTA)]-thatsynthesizedusingsolidandsolid-hybridapproachwiththethermalstabilizerlanthanaandEDTAatthehigh-temperaturehada10-30μmlargeporeporousnetwork-likestructure,afteraluminawascalcinedat1200oCfor1h.Thespecificsurfaceareaoffourspecimenwerebeyond120m2/g,whilethesamplespecificsurfaceareaofx([La(EDTA)]-)=1%wasupto150.36m2/g.
简介:TheeffectsofCeadditiononthequantity,size,distributionofinclusionsandthecontentofoxygen,sulfurandotherhazardousresidualelementsinspringsteelusedasfastenerinhighspeedrailwaywereinvestigatedbymetallographicexamination,SEM-EDSandcompositionanalysis.TheresultsindicatedthatthecontentsofoxygendecreasedwiththeadditionofCe([Ce]<0.1%)andthecontentofsulfurcontinuallydecreasedwithincreasingcontentofCe([Ce]<1.2%).However,withthefurtherincreaseofCeelementaddition,thecontentof[O]andT[O]begantoincrease.ThecontentofCecorrespondingtothelowest[O]andT[O]liedintherangeof0.10%–0.13%and0.045%–0.065%,respectively.TheadditionofCeinspringsteelresultedintheformationofrareearthoxides/oxysulfidesanddecreasedthesizeofinclusionstolessthan3μminglobularorspheroidshape.Moreover,theresidualharmfulelements(As,P,PbandSn)werefoundtoexistintheCe-containinginclusions,whichhadprovedthattheCeadditioncouldcapturetheresidualelementsandsuppresstheirprecipitationbehaviorsinthegrainboundary.
简介:VariousopticalluminescencespectroscopictechniqueswereusedtocharacterizethehighTcsuperconductorYBa2Cu3Ox.TheemissionbandsrevealthatCu3+coexistwithCu2+andCu+inthismaterial.
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简介:Surface-treatedMmNi3.55Co0.75Mn0.4Al0.3alloyasnegativeelectrodematerialofnickel-metalhydridebatterywasemployedtoimprovethehigh-ratedischargeability.SurfacetreatmentwasrealizedbydippingandstirringthealloyintoaHClaqueoussolutionwithvariousconcentrationsatroomtemperature.ThemicrostructureofthealloybeforeandaftersurfacetreatmentwasanalyzedbyX-raydiffraction(XRD)andscanningelectronmicroscopy(SEM).Theelectrochemicalpropertiesbeforeandaftersurfacetreatmentwerecompared,andthealloytreatedin0.025mol/LHClsolutionshowedtheoptimalhigh-ratedischargeability.
简介:CeB6粉末被CeO2,B2O3和Mg作为反应物在被拿的高温度的自我繁殖的合成(SHS)准备。SHS反应的断热的温度和动力学被调查。SHS反应产品和沥滤的产品被X光检查衍射(XRD)和扫描电子显微镜学(SEM)描绘。结果比让反应由自己宣传的1800K,和明显的激活精力(Ea)和反应在微分扫描热量测定(DSC)曲线是的Mg-B2O3-CeO2上订发热的山峰的(n)的显示Mg-B2O3-CeO2反应系统的断热的温度相当高23.03kJ/mol并且1.31,分别地。明显的激活精力更低,因此反应容易发生了。SHS产品由MgO,CeB6和小Mg3B2O6组成了。沥滤的产品由单个CeB6阶段组成了,它的纯净比99.0%高,并且CeB6的平均粒子尺寸比150nm小。
简介:ThephotoluminescencepropertiesofBiTaO4∶Pr3+andBiTaO4atroomtemperaturewerestudied,andtheinfraredtransmissionanddiffusionreflectionspectraofBiTaO4weremeasured.ThephotoluminescencespectrumofBiTaO4peaksatabout420,440and465nm.Therehasanobviousexcitationbandfrom330to370nm.ThephotoluminescencespectrumofBiTaO4∶Pr3+consistsofthecharacteristicemissionofPr3+,anditsmainpeakisat606nmfrom3P0→3H6transitionofPr3+.Itsexcitationspectrumconsistsofthewidebandwithmaximumat325nm,thewidebandintherangeof375~430nm,andthecharacteristicexcitationofPr3+.Thebandsat325nmand375~430nmmaybefromtheabsorptionofthechargetransfertransitionofthetantalategroupanddefectenergylevelsinitsforbiddenband,respectively.ThereisenergytransferfromhosttoPr3+.BecauseboththehostdensityandphotoluminescencepeakintensityofBiTaO4∶Pr3+aresuperiortoPbWO4,BiTaO4∶Pr3+maybeapotentialheavyscintillator.
简介:试图为高温度的熔融的盐反应堆的安装和电极的建设开发材料,在750和950湩爠晥湩浥湥?瑳敲杮桴湥湩?猠汯摩猠汯瑵潩?瑳敲杮桴湥湩?眠牯?慨摲湥湩?愠摮瀠敲楣楰慴楴湯猠牴湥瑧敨楮杮的Ni-11Fe-10Cu的高温度的氧化行为上的艾尔和Y的效果
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简介:(Y,Gd)BxV1-xO4-x:Eu3+phosphorswerepreparedbysolidstatereaction.Theredemissioncolorpurityof(Y,Gd)BxV1-xO4-x:Eu3+phosphorismuchbetterthanthatoftherecentwidely-usedcommercialredemittingphosphor(Y,Gd)BO3:Eu3+anditsrelativeemissionintensityis84%ofthecommercialphosphor(Y,Gd)BO3:Eu3+.Itisexpectedthat(Y,Gd)BxV1-xO4:Eu3+phosphorwillbeapromisingcandidateforPDP(plasmadisplaypanels)application.