简介:Inthispaper,thebrazingmechanismofLY12aluminumalloyatmiddlerangetemperaturewaspresented.TheCsF-AlF3non-corrosivefluxwasutilizedtoremovethecomplexoxidefilmonthesurfaceofLY12aluminumalloy.TheresultsrevealedthattheoxidefilmwasremovedbytheimprovedCsF-AlF3fluxaccompaniedwiththeoccurrenceofreactionaswellasdissolutionandthecompoundsCsFplayedanimportantroletoremovetheoxidefilm.Actually,thehighactivityofflux,say,theabilitytoremovetheoxidefilm,wasduetothepresenceofthecompounds,suchasNH4F,NH4AlF4andcompositemoltensalt.TheproductionofHFwasthekeyissuetoacceleratethereactionandenhancetoeliminatetheoxidefilmbydissolution.ItwasfoundthattherareearthelementLaatsmallpercentagewasnotenrichedattheinterface.Moreover,therareearthfluorideenhancedthedissolutionbehavior.
简介:在催化剂P-TSA的作用下,运用原位溶液-凝胶法,将BGPPO、DDM和TEOS合成了具有纳米结构的含磷环氧/硅黏土复合材料,经傅立叶红外转移(FTIR)、核磁共振(NMR)和扫描电子显微镜(SEM)表征后发现,环氧树脂中的硅粘土达到了纳米级尺寸,并且,随着粘土含量的增加,
简介:Anewenvironmentalfriendlycatalyst,H4SiW12O40/PAnwaspreparedandidentifiedbymeansofFT-IR,XRDandTG/DTA.Cyclohexanone1,2-propanediolketalwassynthesizedfromcyclohexanoneand1,2-propanediolinthepresenceofH4SiW12O40/PAn.Thefactorsinfluencingthesynthesiswerediscussedandthebestconditionswerefoundout.Theoptimumconditionsare:molarratioofcyclohexanoneto1,2-propanediolis1:1.4,thequantityofcatalystisequalto1.0%offeedstocks,andthereactiontimeis40min.H4SiW12O40/PAnisanexcellentcatalystforsynthesizingcyclohexanone1,2-propanediolketalanditsyieldcanreachover96.5%.
简介:ThevacuuminductionbrazingofSiCparticulatereinforcedLY12alloymatrixcompositeusingAl-28Cu-5Si-2Mgfillermetalhasbeencarriedout.Themicrographofthejointinterfacewasobservedbyscanningelectronmicroscopy.Thejointstrengthwasdeterminedbysheartests.Theresultsshowthatbrazingtemperature,holdingtime,SiCparticlevolumepercentageandpostheattreatmentinfluencejointstrength.SiCparticleshappeninthebrazingseamandthedistributionofSiCparticlesinthejointisnotuniform.Particle-poorzonesinthejointexistnearthebasemetal,andparticleconcentratezonesexistinthecenterofthebrazingseam.Inaddition,thefailureofthecompositeispredominantlyinitiatedbytherootingofSiCparticleinthebrazingseamandthemicro-crackexpandedalongthebrazingseamwithlowenergy.
简介:Inthispaperanewmethodforpreventingweldinghotcracking—theinversestrainmethod(ISM)isdevelopedontheprincipleofweldingmechan-ics.EffectivenessandfeasiblityofmethodinpreventingweldinghotcrackingofhighstrengthaluminumalloyLY12CZbysynchronousrollingduringwelding(SRDW)alongbothsidesoftheweldatasuitabledistancebehindtheweldingarcareexamined.ExperimentalresulteindicatethatweldinghotcrackingofLY12CYcanbeeffectivelypreventedandthemechanicalpropertiesofweldedjointcanalsobeimprovedbythemethod.Itisanimportantnewsolutionforpreventinghotcrackinginweldingofsheetmetal.