简介：本试验利用CMT-TWIN双丝焊接技术,在Q235基体上堆焊Φ1.2ER5356和Φ1.2ER50S-6,以获得致密、无裂纹孔洞等缺陷的Fe-Al堆焊层。堆焊层主要由柱状晶组成,内部析出了细小的弥散相,EDS表明堆焊层存在Fe3Al。硬度测试表明：熔合区硬度分布不均匀,硬度峰值达450HV,而焊缝中心区硬度大致在350-400HV之间,表明此区域可能含Fe3Al较多。

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简介：ThefrictionandwearbehaviorofFe-Alintermetallicsbasedcoatingproducedbyhighvelocityarcsprayingtechniqueunderdryslidingatroomtemperaturewereinvestigatedusingaball-on-disctribotester.Theeffectofslidingspeedonfrictioncoefficientandwearofthecoatingwasstudied.Thewornsurfaceofthecoatingwasanalyzedbyscanningelectronmicroscope(SEM)toexploreslidingfrictionandwearmechanism.Theresultsshowthatthevariationsoffrictioncoefficientcanbedividedintothreedistinctstepsduringthetrail.Boththefrictioncoefficientandthewearofthecoatingincreasewithincreasedslidingspeedduetoacceleratedcrackpropagationrateandlamellarstructurewithpoorductilityofthecoating.Thecoatingsurfaceissubjectedtoalternatelytensilestressandcompressionstressduringslidingwearprocess,andthepredominantwearmechanismofthecoatingsappearstobebrittlefractureanddelamination.

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：Fe3AlandCr18-Ni8steelwerebondedinvacuumandaninterfacewasformedbetweenFe3AlandCr18-Ni8steel.Stressdistributionatthediffusion-bondedinterfacewasresearchedbynumericalsimulationandfiniteelementmethod(FEM).TheresultsindicatedthatthepeakstressappearedattheinterfacenearCr18-Ni8steelside.Thisisthekeyfactortoinducecrackatthisposition.Withtheenhancementofheatingtemperature,thepeakstressatthebondedinterfaceincreases.Whenthetemperatureis1100℃,thepeakstressisupto65.9MPa,whichisbiggerthanthatat1000℃by9.4%.Inaddition,thepeakstressbecomesbiggerwiththeincreaseofthethicknessofbasemetalfrom1mmto8mm.Whilethethicknessismorethan8mm,thepeakstressvariesslightlywiththechangeofthethickness.

简介：ThevacuuminductionbrazingofSiCparticulatereinforcedLY12alloymatrixcompositeusingAl-28Cu-5Si-2Mgfillermetalhasbeencarriedout.Themicrographofthejointinterfacewasobservedbyscanningelectronmicroscopy.Thejointstrengthwasdeterminedbysheartests.Theresultsshowthatbrazingtemperature,holdingtime,SiCparticlevolumepercentageandpostheattreatmentinfluencejointstrength.SiCparticleshappeninthebrazingseamandthedistributionofSiCparticlesinthejointisnotuniform.Particle-poorzonesinthejointexistnearthebasemetal,andparticleconcentratezonesexistinthecenterofthebrazingseam.Inaddition,thefailureofthecompositeispredominantlyinitiatedbytherootingofSiCparticleinthebrazingseamandthemicro-crackexpandedalongthebrazingseamwithlowenergy.

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简介：BasemetalsofdomesticpipelinesteelswereusedtostudytheeffectofMnoncorrosionpropertiesofSSCC(SulfideStressCorrosionCracking),andweldswerecarriedouttostudytheeffectofMnSoncorrosionpropertiesofHIC(HydrogenInducedCracking)bothinsolutionswithwethydrogensulfide(H2S).TheywererespectivelyconductedbyreferringtothestandardsofSSCCandHIC.TestingresultsrevealedthatwiththeincreaseofcontentMn,theresistanceofSSCCwillbedecreased,fromthepointofmetallurgicview,anditisMnelementnotCelementtoleadtothetestingresultsofSSCC.Meanwhile,evenundertheconditionwithoutinclusionsMnS,HICinweldsstilloccurred.Thatistosay,MnSisnotnecessaryforHIC,thepresenceoflocalbandedstructuresinwhichMnandPareinclinedtoaggregatecausetothephenomenaofHIC.

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简介：Carbonnanotube(CNT)reinforcedaluminummetalmatrixcompositeswereweldedbyelectronbeamweldingandthemicrostructuresofweldedjointswereinvestigated.TheresultshowedthattheinterfacialreactionhappenedbetweentheCNTsandAlmatrix,whichresultedinproducingbrittleAl_4C_3compoundsinelectronbeamwelds.Theextentofinterfacialreactionvariesgraduallyinthedepthandwidthdirection.ThelengthofthereactantsAl_4C_3becameshortduotothetemperaturegradientinthemoltenpool.ThequantityandsizeofAl_4C_3compoundsincreasedwiththeincreaseofbeamcurrentandthedecreaseofweldingspeedinthemiddlezoneofweld.However,noneedle-likephaseAl_4C_3wasobservedinHAZ.

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简介：Sinceamorphousalloyshavewiderapplication,theycannotbefabricatedusingtheconventionalcoolingvelocity.ThebarmaterialplasmasprayingisadoptedtofabricateFebaseamorphousalloyinthisinvestigation.Thecrystallizationdegree,microstructure,micro-hardness,composition,crystallizationtemperatureoftheamorphousalloyandtheflyingrulesoftheatomizedparticlesintheprocessoftheplasmasprayaretested.Theresultsshowthatthealloypreparedhasthehighamorphousdegreeandhomogeneousmicrostructure,micro-hardnessandthecrystallizationtemperaturecanreach1187HVand531℃respectively.Theatomizationisverywellduringtheprocessofplasmaspraying;andthereishighthermalgradient,thecoolingvelocityreaches6.07×107K/s.

简介：BondingofAl2O3tocuisperformeddirectlyusingTifoilattemperatureof1273K.Themicrostructureofthejointinterfaceisinuestigatedthroughscanningelectronmicroscope（SEM）,electron.probemicroanalysis（EPMA）andX-raydiffraction（XRD）.theeffectoftheinitialtifoilthicknessonthereactionlayerthicknessandthejointStrengthareinvestigated.

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简介：Dynamicsinpartialtransientliquidphasebonding(PTLPbonding)ofSi3N4ceramicwithTi/Cu/Timulti-interlayerwassystematicallystudiedthroughmicro-analysisofjointinterfaces.Theresultsshowthatgrowthofreactionlayerandisothermalsolidificationprocessiondoatthesametime.GrowthofreactionlayerandmovingofisothermalsolidificationinterfaceobeytheparaboliclawgovernedbythediffusionofparticipatingelementsduringthePTLPbonding.Coordinationoftheabovetwodynamicsprocessisdonethroughtimeandtemperature.Whenreactionlayerthicknessissuitableandisothermalsolidificationprocessisfinished,thehighbondingstrengthatroomtemperatureandhightemperatureareobtained.

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简介：Inordertosolvethehigh-priceandshort-lifetimeproblemsofthecutterofagriculturalmachinery,andimprovethewearresistanceofthecutter,theTiCN/FemetalceramiccompositecoatingwaspreparedonthesubstrateofQ235steelbyreactionnitrogenarccladdingtechnique.ThemixturepowderoftitaniumandgraphitewaspreplacedontheQ235steelsurfaceafterintensivemixingbyplanetaryballmillandgluingwithstarchbinder.Themicrostructureandphaseofthecoatings,interfacebehaviorbetweencoatingsandthesubstratewereinvestigatedbyscanningelectronicmicroscopeandX-raydiffractometer.Themicro-hardnessdistributionofthecoatingsectionwastestedbymicro-hardnesstester.Frictioncoefficientandwearweightlossweremeasuredbyabrasionmachine.Wearingsurfacemorphologywasinvestigatedbyscanningelectronicmicroscope.TheresultsshowthatanexcellentbondingbetweenthecoatingsandtheQ235steelsubstrateisensuredbythestrongmetallurgicalinterfaceandphaseofthecoatings.ThecoatingsaremainlycomposedofTiCN.Thehighestmicrohardnessofthecoatingsreaches1089HVO.2,whilethemicro-hardnessofQ235steelsubstrateisonlyabout286HVO.2.Theanti-abrasivetestresultsshowthatthewearresistanceofthecladdingcoatingisbetterthanthatofquenchedandtempered65Mnsteelwhichisoftenusedascutterofagriculturalmachinery.ThefieldtestresultsshowthattheTiCN/Femetalceramiccompositecoatingpreparedbyreactionnitrogenarccladdingisfeasibletothemanufactureandremanufactureofthecutterofagriculturalmachinery.