简介:BondingofAl2O3tocuisperformeddirectlyusingTifoilattemperatureof1273K.Themicrostructureofthejointinterfaceisinuestigatedthroughscanningelectronmicroscope(SEM),electron.probemicroanalysis(EPMA)andX-raydiffraction(XRD).theeffectoftheinitialtifoilthicknessonthereactionlayerthicknessandthejointStrengthareinvestigated.
简介:CreeppropertyofsolderalloysisoneoftheimportantfactorstoaffectthereliabilityofsolderedjointsinSMT(surfacemounttechnology).Particle-enhancementisawaytoimprovethepropertiesofsolderalloysandhascausedmuchmoreattentionthanbefore.Temperaturesappliedtosolderedjointsareoneoftheprimaryfactorsofaffectingcreeppropertiesofparticleenhancementcompositesolderedjoints.Inthispapersingleshearlapcreepspecimenswitha1mm2cross-sectionalareawerefabricatedusingCuparticleenhancement63Sn37Pbbasedcompositesolderedjointsand63Sn37Pbeutecticsolderedjointstoexaminetheinfluenceoftemperatureoncreepbehaviorofsolderedjoints.ResultsindicatedthatthecreepresistanceofsolderedjointsofCuparticleenhancement63Sn37Pbbasedcompositesolderedjointwasgenerallysuperiortothatoftheconventional63Sn37Pbsolderedjoint.Atthesametime,creeprupturelifeofthecompositesolderedjointwasdeclinedwithincreasingtemperatureanddropfasterthanthatoftheconventional63Sn37Pbeutecticsolderedjoint.
简介:Forthedevelopmentofalow-melting-pointfillermetalforbrazingaluminumalloys,aseriesofAl-Si-Cu-(Ni,Sn,Zn)fillermetalshavebeenstudied.Throughdifferentialthermalanalysis(DTA),themeltingtemperaturesofsuchAl-Si-Cu-(Ni,Sn,Zn)fillermetalsweredetermined.Theresultsshowthattheadditionof3wt.%-5wt.%SnintotheAl-6Si-15Cufillermetalcausesitssolidustemperaturetodecreasebyabout12℃.ThefillermetalwiththecompositionAl-6Si-l5Cu-2Niisproposed,whichpossessesameltingtemperaturerangeof512℃to520℃andamicrostructarethatincludesanAl-Cueutecticphases,Al-Si-Cueutecticphases,siliconparticlesandCu_2Al,AlNi_3,Al_7Cu_4NiandAl_3Ni_2intermetalliccompounds.Anadditionof5wt.%-7wt.%ZnintosuchAl-Si-Cufillermetalscausetheirsolidustemperaturestodropfurthertoavaluelowerthan498℃.MetallographicobservationsindicatethattheadditionofZnintotheAl-Si-CufillermetalinhibitstheformationoftheAl-Si,Al-CuandAl-Si-Cueutecticphases.TheremainingphasesareaAl_2Cuintermetalliecompound,anα-Alsolidsolutionandsiliconparticles.
简介:Cracksmayeasilyoccurinthefusionweldbetweenvanadiumalloysandstainlesssteelduetothebrittleintermetallicsandweldingstress.Thehighvacuumelectronbeambraze-weldinghasbeensuccessfullyusedtojoinvanadiumalloy(V-5Cr-5Ti)tostainlesssteel(HR-2)withelectroplatedCuandAgcoating.Toinvestigatetheeffectsofelectroplatedcoatingontheweldability,thejointappearance,themicrostructureandthemechanicalpropertiesofthejointshavebeenthoroughlyanalyzed.Theresultsshowthatthejointsurfaceconfigurationwasgoodandrootreinforcementwasfullandsmooth.Areactionzone(RZ)wasgainedontheinterfacebetweentheVSCrSTialloyandHR-2stainlesssteelbasemetals.Thewidthofreactionzoneatthetopofthejointwasupto0.65mm,widerthanthatinthebottomofthejoint(0.46mm).Thereactionzoneconsistedofconsiderablysmallerdendriticstructureswithanaveragegrainsizeoflessthan10μm.ElementAgandCualmostenrichedtheinterfacebetweenV-5Cr-5TialloysubstrateandRZ,servingasaphysicalbarrierwhichdecreasesoravoidstheformationofintermetallics.Themaximumtensilestrengthofvanadiumalloy/stainlesssteeldissimilaralloyjointwasmorethan300MPa.Thejointwasdefectsfree.
简介:我国是铝的第一生产大国,但是在上世纪80年代初,因铝导体生产工艺低下严重影响了铝导体的使用。主要制约铝导体推广和使用因素是达不到国际公认的61%IACS导电率水平,以及与导电率相矛盾的断裂强度与伸长率,这就严重地制约了铝导体的使用。随着科学技术的不断发展,铝导体加工工艺的不断进步,人们想出了可在铝的熔炼过程中加入一些其他元素,来弥补铝导体性能的不足,发展到今天就形成了铝合金导体。从2005年开始,铝合金导体在电缆中的使用逐步发展起来,由于铝合金导体除了在导电率上与铜存在差距,在导体压蠕变、柔韧性、抗腐蚀以及电缆敷设方面都优于铜导体电缆,同时,在导电率上也可以通过扩大导体截面来弥补载流量的缺陷,从而人们也慢慢开始使用铝合金材料作为电缆导体。
简介:SolderingofLD31aluminumalloysusingSn-PbsolderpasteafterelectricbrushplatingNiandCucoatingswasnvestigated.ThetechnologyofelectricbrushplatingNiandCuwasstudiedandplatingsolutionwasdeveloped.Themicrostructureofthecoatings,solderedjointandfracturefacewereanalyzedusingopticmicroscopy,SEMandEDX.Theshearstrengthofsolderedjointcouldreachashighas26.83MPa.Theresultsshowedthatreliablesolderedjointcouldbeobtainedat230℃,theadhesionofcoatingsandLD31aluminumalloysubstratewashighenoughtobearthethermalprocessinthesoldering.
简介:IntheautomaticCO2arcwelding,thealterationoftheverticaldistancebetweentheweldingtorchandtheworkpiecehasastrongeffectontheweldingparameterssuchasweldingcurrentandvoltage,withtheresultthattheappearanceandqualityofweldarenotsteady.Toweakentheinfluenceofthedistancealteration,amethodisputforwardinthepaper.Themethodisthatthealternatewire-feedcontrolisusedforcompensatingtheweldingcurrent.Onthebasisoftheoreticalanalysis,astaticnumericalmodelforalternatewire-feedcontrolisestablished.Theexperimentsshowthatthemodel-basedregulationofthewirefeedratecancompensatetheweldingcurrentandensuretheappearanceofweld.Whenthealterationofverticaldistancebetweenthetorchandtheworkpieceisgreater,notonlyisthewirefeedrateregulated,buttheoutputvoltageofthepowersourceisadjustedtoensuretheappearanceandqualityofweld.