简介:Thenormallycenteredelectronbeamandnon-centeredelectronbeamweldingofTiAltoTC4wasinvestigatedinordertoanalyzetheelectronbeamweldabilitybetweenTiAl/TC4dissimilarmaterials.MacroscopiccoldcrackeasilyoccurrednearTiAlsubstrateinthejoints.Theoptimaltensilestrengthwasrelatedtotheweldingheatinput.Theweldstructureswerecomposedofbulkycolumnargrainsandequiaxedgrains.Theisolatedphasesconsistedoflargequantitiesofα2-Ti3Alphase,smallquantityofB2phase,γ-TiAlphaseandYAl2phase.InsufficientmeltingofthebasemetaloccurredintheweldwhenthebeampositionleanedtotheTC4side.Thetensilestrengthcouldbeimprovedwhenthedeflectionwaslimitedintheoptimumrange.Otherwise,non-fusionzonewaseasilygeneratedintheweld,whichledtothelowtensilestrength.
简介:本文针对N4/1Cr18Ni9Ti与N4/0Cr25Ni20复合板的特殊焊接要求,根据NB/T47014—2011《承压设备焊接工艺评定》的要求,制备2块N4/1Cr18Ni9Ti试板,2块N4I/0Cr25Ni20试板,尺寸均为500mmX150mmX(4+14)mm。不锈钢基层采用GTAW打底,焊丝选用HOCr21Ni10,SMAW填充与盖面,焊条选用A302与A402。镍复层的焊接采用手工钨极氩弧焊,焊丝选用含Ti、AI等脱氧元素的ERNi-1焊丝,保护气体选择98%Ar+2%H2。试板焊接完成,外观检验合格后进行100%RT,检测结果符合JB厂r4730,2—2005I级合格,镍复层进行100%PT,检测结果符合JB/T4730.5—2005I级。两种焊接试板分别取样并做拉伸、弯曲力学性能分析,镍复层焊缝做化学成分分析。通过两块焊接试板试验对比,不锈钢基层焊接材料选择HOCr21Ni10焊丝与A302焊条。镍复层焊接采用ERNi-1焊丝,焊接保护气体为98%Ar+2%H2。通过焊接工艺评定试验研究,解决了N4/1Cr18Ni9Ti与N4I/0Cr25Ni20复合板焊接问题,提高了用户坩埚的返修质量与再次使用寿命,为使用单位节约了成本。
简介:ThedosimetricphosphorsLi_3PO_4:M(M=Tb,Cu)wereproducedbymodifiedsolid-statemethod.ThestructuralandmorphologicalcharacterizationwascarriedoutthroughX-raydiffraction(XRD)andscanningelectronmicroscope(SEM).Additionally,thephotoluminescence(PL),thermoluminescence(TL)andopticallystimulatedluminescence(OSL)propertiesofpowderLi_3PO_4dopedwithTbandCuwerestudied.ItisadvocatedthatLi_3PO_4:CuphosphornotonlyshowshigherOSLsensitivity(25timesormore)butalsogivesfasterdecayinOSLsignalsthanthatofLi_3PO_4:Tb~(3+)phosphor.Theminimumdetectabledose(MDD)ofLi_3PO_4:M(M=Tb,Cu)phosphorsisfoundtobe21.69×10~(-3)and3.33×10~(-6)J·kg~(-1),respectively.InOSLmode,phosphorshowslineardoseresponseintherangeof0.02-20.00J·kg~(-1).InTLmode,sensitivityofLi_3PO_4:CuphosphorismorethanthatofLi_3PO_4:Tbphosphor.Thekineticsparameterssuchasactivationenergyandfrequencyfactorsweredeterminedbypeakshapemethod,andphotoionizationcrosssectionsofpreparedphosphorwerecalculated.
简介:有一致的杆形状的单斜晶的LaPO4nanostructures被一个简单大音阶的第五音胶化方法成功地综合了。过程包含形成同类,透明,metal-citrate-EDTA胶化先锋,由锻烧列在后面支持胶化先锋的热分解产出LaPO4nanoparticles。他们的形态学和结构被XRD,TEM,TG-DSC和HRTEM描绘。结果显示单个单斜晶的阶段LaPO4nanorods乐意地在800点被获得吗?在3h以内。而且,做Eu3+的LaPO4nanocrystals的光致发光(PL)描述被执行。在PL性质上做内容的锻烧温度和Eu3+的效果详细被详细描述。房间温度光致发光(PL)描述表明光亮度以及到5D0-7F2的5D0-7F1的紧张比率高度依赖于锻烧温度,并且Eu0.05La0.95PO4nanophosphor与最强烈的排放显示出相对有希望的PL表演。
简介:InordertoimprovethehydrogenstoragepropertiesofLiBH_4-MgH_2composite,twodifferentkindsofNb-basedcatalysts,NbCandNbF_5,wereaddedtoLiBH_4-MgH_2compositebyballmilling,andtheeffectofcatalystsonhydrogenstoragepropertiesofthemodifiedLiBH_4-MgH_2systemwasinvestigated.TheexperimentalresultsshowthatLiBH_4-MgH_2compositeisatwo-stepdehydrogenationprocess,andNb-basedcompoundscanremarkablyenhanceitsdehydrogenationkinetics.Forthecompositewithoutadditionofcatalysts,thestartingdecompositiontemperatureforthefirstdehydrogenationstepisaround320℃,andthereisalongperiodofincubationtime(around220min)fortheoccurrenceoftheseconddecompositionstepevenathightemperatureof450℃.Itneedsmorethan10htocompletethedecompositionprocessandreleasearound9wt%H_2.Afteradditionof5mol%NbF_5,thestartingdecompositiontemperatureforthefirstdehydrogenationstepisaround150℃,thereisnoincubationtimefortheseconddecompositionstep,andittakesaround40mintocompletethesecondstepandreachesatotaldehydrogenationcapacityof9.5wt%.NbF_5hasbettercatalyticeffectthanNbC.Basedonthehydrogenation/dehydrogenationbehaviorsandstructuralvariation,themechanismofcatalyticeffectwasdiscussed.