简介:ThenatureofbondinginthetitlecompoundshasbeenstudiedbyusingCASSCFandFOCItechniques.ThegroundstatesofPtCandPtNarefoundtobe1Σ+and2Πstatearisingprimarilyfrom:…1σ22σ21π41δ43σ2and…1σ22σ21π41δ43σ22π1configurationrespectivelyandbothofwhichformtriplebond(ones,twoπbonds),butthebondofPtCismuchstrongerthanthatofPtN.
简介:Theelevatedtemperaturetensileexperimentshavebeencarriedoutonthemagnesiumalloyandresultsindicatethatthemagnesiumalloyhasexcellentsuperplasticproperty.Gleebe-1500testingmachinewasusedinthediffusionbondingexperimentonthesuperplasticmagnesiumalloy.Then,theshearstrengthofthejointsunderdifferentconditionsisobtainedthroughsheartestingandtheoptimumprocessingparametersforthediffusionbondingareachieved.Bymetallurgicalmicroscopeandscanningelectronmicroscope(SEM),itisrevealedthatthemicromechanismofdiffusionbondingistheslideofgrainboundariescausedbythegrowthofgrainsandatomdiffusionofthesuperplasticmagnesiumalloy.
简介:TheZrcoatingwasdepositedontitaniumsurfaceusingthemagnetronsputteringtechnique.EffectsofZrcoatingonmicrostructureandmechanicalpropertiesofporcelainfiredtotitaniumhavebeeninvestigated.Theresultsshowthatinterdiffusionofelementsoccursduringporcelainfiring,andtheZrcoatingcaneffectivelyprotecttitaniumsurfacefromexcessoxidation.ThestrengthofbondzonewithZrcoatingdepositedfor1hourreaches29.7MPa,whichhasincreasedby26.4%ascomparedwiththatofbondzonewithoutcoating(23.5MPa).
简介:Theceramicsettingbindersobtainedbymeansoftherawmixmechano-chemicalprocessing(mechanicaldispersionandchemicalinteractionprocessescombination),usedforbondingrefractoryconcretes,becomemoreavailablewithasubsequentincreasedinterestintheirpropertiesbecausetheydevelopinitialstrengthduringaheatupoftheunitswithin8-10h,incontrastto24hafterplacementforhighAl2O3cements(HAC).Thisstrengthdevelopmentenableshightemperatureprocessingunitstoberelinedwithminimumturnaroundtime,thusprovidingafavoredcost/performanceratio.Thepresentpaperidentifiesthepredominantphosphatephasesresponsiblefordevelopinggoodmechanical-strengthpropertiesofzirconiaandaluminaconcretesbondedwithmechano-chemicalbinders.Itsetsoutthecolloidandcrystallinephasesresultedfrominterphaseinteractionthatprovidethebasisforhighconcentratedbondingsuspensions(HCBS)technologyusefultotherefractoryindustry.
简介:Thevacuumdiffusionbondingoftitaniumalloytotin-bronzehasbeenstudiedandthefeasibilityandappropriateprocessingparametershavebeeninvestigated.Themaximumtensilestrengthofthejointsis168MPa,andafirmjointisobtained.ThemicrostructureofdiffusionbondedjointhasbeenobservedbySEM.X-rayandEPMA,andthemainfactorsaffectingdiffusionbondinghavebeenanalyzed.TheintermetalliccompoundsTi2CuandTiCuwereformedneartheinterface.Thewidthandquantityoftheintermetalliccompoundincreaseswiththeincreaseofthebondingtime.Theformationoftheintermetalliccompoundsresultsinembrittlementofthejointandthepoorjointproperties.
简介:ThehydrogenbondpercentageanditstemperaturedependenceofthethreeTPUsamplessynthesizedfrompolytetrahydrofuran,4,4-diphenylmethanediisocyanate,N-methyldiethanolamineor1,4-butanediolwerestudiedbymeansofIRthermalanalysis.TheenthalpyandtheentropyofthehydrogenbonddissociationweredeterminedbytheVantHoffplot.
简介:Theadsorptionisothermsofcaffeinefromaqueoussolutionontothreehydrogendonatingadsorbents-hydroxypolystyrene,polystryene-azo-pyrogallol,andD72resin-weremeasured.TheadsorptionenthalpiescalculatedfromtheisothermsaccordingtotheClausisu-Clapeyronequationwere-24-36kJ/mol,-32-37kJ/mol,and-19-24kJ/molrespectively.Thesevaluesimpliedthattheadsorptionprocesseswerebasedonhydrogenbonding.Furthermore.themechanismoftheadsorptionofcaffeineontoD72resinwasstudiedbyIRspectraandthesmallmolecularmodelexperiments,andtheresultsshowedthattheadsorptionofcaffeineontohydrogendonatingadsorbentswasbasedonhydrogenbonding.
简介:Twohydrogen-bondingadsorbents-macroporouscrosslinkedpoly(P-nitrostyrene)andpoly(p-vinylbenzylamide)-weresynthesized,andtheadsorptionpropertyofphenolfromcyclohexanesolutionontotheadsorbentswasstudied,ThedifferentialadsorptionheastsforvariedadsorptioncapacitiescalculatedfromtheadsorptionisothermsaccordingtotheClaperyron-Clausiusequationlayintherangeofhydrogenbondenergy(8-50kJ/mol),Theadsorptioncapaccityofo-nitrophenolincyclohexanewasmochlessthanthatofphenolunderthesamecondition.Theadsorptioncapacityofphenolfromcyclohexaneontopolyacrylonitrilewasmuchlessthanthatontopoly(p-nitrostyrene)orpoly(p-vinylbenzylamide),Alltheseresultsrevealedthatadsorptionofphenolfromcyclohexanebypoly(p-nitrostyrene)orpoly(p-vinylbenzylamide)isbasedonhydrogen-bonding.
简介:Factorsinfluencingbondingstrengthoflaminatedbamboostripslumber(LBSL)wereinvestigatedinthispaper.Inordertofindanoptimizedtechnology,thispaperinvestigatedhowthethicknessofbamboostrips,theassemblyorientationofbamboocurtain,thetypeofadhesives,aswellascouplingagenttreatmentofbamboocurtainaffectedthebondingstrength.Thefollowingconclusionsweredrawn:1)Thethinnerthethicknessofthebamboostrips,thebiggerthebondingstrengthofLBSL;2)Theassemblyor...
简介:BondingofAl2O3tocuisperformeddirectlyusingTifoilattemperatureof1273K.Themicrostructureofthejointinterfaceisinuestigatedthroughscanningelectronmicroscope(SEM),electron.probemicroanalysis(EPMA)andX-raydiffraction(XRD).theeffectoftheinitialtifoilthicknessonthereactionlayerthicknessandthejointStrengthareinvestigated.
简介:Wehavestudiedtheelectronic,bondingandenergeticcharacteristicsoftheFe-Sibinarysystemusingthetight-bondingextendedHuckelmethod.AmongtheFe-Sibinarycompounds,FeSihasthemostsymmetricgeometricarrangementinthecrystalstructure.Italsopossessesthelargestcohesiveenergyperatom.ThiscorrelatestothefactthatFeSiisthemoststablecongruently-meltingcompoundinthebulkphasediagram.Anestimateofinteractionenergiesbetweendifferentatomsisalsogiven.
简介:Possibilitiesforenhancementofcatalyticreactionratebycombiningphasetransfercatalysisandhydrogenbondingofthecatalystwiththesubstrateandreagentwerestudied.Aphasetransfercatalystlibrarywithsixtypolystyrene-supportedquaternaryammoniumsaltcatalystswassynthesized.ThereductionofacetophenonebyNaBH4wasusedastheprobingreactiontoselectouttheostactivecatalystinthelibrarybyusingiterativemethod.whichwasthegel-typetriethanolamineaminsatingstronglyasicanionexchangeresinwiththecrosslinkingdegereeof2%Ahydrogenbondingassistedcatalyticmechanismwasproposedtoexplainthehighcatalyticactivityofthecatalyst.
简介:Theliquid-filmsolution-diffusionbondingofZCuBe2.5alloyswasconductedusingCu-basedalloypowders.Thetensilestrengthofthebondingtimedecreasesandtheinterfacemigrationvelocityincreasesbondingtime,thethicknessofdiffusionlayerincreaseswiththeincreaseoftemperaturegradient,andthistendencybecomesmoreremarkablewiththeprolongingofbondingtime.
简介:Thebondingofsteelplatetoaluminumliquidwasconductedusingrapidsolidification.Theinfluenceofdiffusiontimeoninterfacialstructurewasstudied.Theresultsshowedthatundertheconditionof750℃forthetemperatureofaluminumliquidand200℃forthepreheattemperatureofsteelplate,whendiffusiontimewasshorterthan4.3s,therewasonlyFe-Alsolidsolutionattheinterface.Whendiffusiontimewaslongerthan4.3s,Fe-Alcompoundbegantoformattheinterface.TherelationshipsbetweendiffusiontimetandthicknessofFe-AlcompoundlayerHareH=-9.72+2.62t-0.08t^2(4.3s≤t≤15s)andH=2.79+0.647t=0.033t^2(t>15s).