简介:ThefracturetoughnessandfractureworkofAl2O3/SiCprismaticceramiccompositeswasevaluatedinthispaper,whichshowedthefractureenergywasimprovedgreatly.Basedontheobservationforcrackpropagationandfracturemorphology,thefracturebehavioroftheprismaticcompositeswasanalyzed.Inthebendingtest,thecompositesdisplayedanon-catastrophicbehaviorandagracefulfailurewithreasonableload-carryingcapability.
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简介:Diamond-likecarboncoatingshavebeenusedassolidlubricatingcoatingsinvacuumtechnologyfortheirgoodphysicalandchemicalproperties.Inthispaper,thehybridtechniqueofunbalancedmagnetronsputteringandplasmaimmersionionimplantation(PIll)wasadoptedtofabricatediamond-likecarbon-basedfunctionallygradientfilm,N/TiN/Ti(N,C)/DLC,onthe304stainlesssteelsubstrate.ThefilmwascharacterizedbyusingRamanspectroscopyandglancingX-raydiffraction(GXRD),andthetopographyandsurfaceroughnessofthefilmwasobservedusingAFM.Themechanicalpropertiesofthefilmwereevaluatedbynano-indentation.Theresultsshowedthatthesurfaceroughnessofthefilmwasapproximately0.732nm.Thehardnessandelasticmodulus,fracturetoughnessandinterfacialfracturetoughnessofN/TiN/Ti(N,C)/DLCfunctionallygradientfilmwereabout19.84GPa,190.03GPa,3.75MPa.m1/2and5.68MPa@m1/2,respectively.ComparedwiththatofDLCmonolayerandC/TiC/DLCmultilayer,thisDLCgradientfilmhasbetterqualitiesasasolidlubricatingcoating.
简介:StructurehealthmonitoringbasedondiagnosticLambwaveshasbeenfoundtobeoneofthemostpromisingtechniquesrecently.Thispaperhasabriefreviewofthenewdevelopmentsonthismethodincludingthebasicnovelofthemethod,fundamentalsandmathematicsofLambwavepropagation,narrowbandandwidebandLambwaveexcitationmethods,optimizationofexcitationfactorsanddiagnosticLambwaveinterpretationmethods.
简介:Polyacrylate-basedconductivecoatingswerepreparedfrompolyacrylateemulsionasmatrixandcarbonblack(CB)whosesurfacewastreatedwithtitanatecouplingagentasconductingparticles.OnekindoforganiccrystalwasaddedtostudyitseffectsontheelectricalconductivityandPTC(positivetemperaturecoeffi-cient)effectoftheconductivecoatings.ExperimentalresultsshowthatthecoatingscontainingonlypolyacrylateemulsionandCBexhibitanexcellentelectricalconductivitybutbadPTCeffect,andwhenorganiccrystalisadded,PTCeffectischaracterizedandcanincreaseby2ordersofmagtitude.Thecriticaltransformationtemperatureofpolyacrylateemulsion/CBPTCcompositesisdecidedbymeltingpointoforganiccrystals.
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简介:TherelationshipbetweenCharpyabsorbedenergyandthefracturetoughnessbymeansofthe(cracktipopeningdisplacement(CTOD))methodwasanalyzedbasedontheWeibullstresscriterion.TheCharpyabsorbedenergyandthefracturetoughnessweremeasuredfortheSN490Bsteelundertheductile-brittletransitiontemperatureregion.FortheinstrumentedCharpyimpacttest,thecurvesbetweentheloadingpointdisplacementandtheloadagainsttimewererecorded.ThecriticalWeibullstresswastakenasafracturecontrolledparameter,anditcouldnotbeaffectedbythespecimenconfigurationandtheloadingpatternbasedonthelocalapproach.TheparameterscontrolledbrittlefractureareobtainedfromtheCharpyabsorbedenergyresults,thenthefracturetoughnessforthecompacttension(CT)specimenispredicted.Itisfoundthattheresultspredictedareingoodagreementwiththeexperimental.ThefracturetoughnesscouldbeevaluatedbytheCharpyabsorbedenergy,becausethelocalapproachgivesagooddescriptionforthebrittlefractureeventhoughtheCharpyimpactspecimenortheCTspecimenisusedforthegivenmaterial.
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简介:Sheetmetalformingiswidelyappliedtoautomobile,aviation,spaceflight,ship,instrument,andapplianceindustries.Inthispaper,basedonanalyzingtheshortcomingofgeneralfiniteelementanalysis(FEA),theconceptionofparametricfiniteelementanalysis(PFEA)ispresented.Theparametricfiniteelementanalysis,artificialneuralnetworks(ANN)andgeneticalgorithm(GA)arecombinedtoresearchthoroughlyontheproblemsofprocessparametersoptimizationofsheetmetalforming.Theauthorprogramstheoptimizationschemeandappliesitinaresearchofoptimizationproblemofinsidesquareholeflangingtechnologicalparameters.Theoptimizationresultcoincideswellwiththeresultofexperiment.Theresearchshowsthattheoptimizationschemeoffersagoodnewwayindiedesignandsheetmetalformingfield.
简介:AnewmethodforcorrosionprotectionofAl-basedmetalmatrixcomposites(MMC)wasdevelopedusingtwo-stepprocess,whichinvolvesanodizinginH2SO4solutionandsealinginrareearthsolution.Corrosionresistanceofthetreatedsurfacewasevaluatedwithpolarizationcurves.TheresultsshowedthattheeffectoftheprotectionusingrareearthsealingisequivalenttothatusingchromatesealingforAl6061/SiCp.TherareearthmetalsaltcanbeanalternativetothetoxicchromateforsealinganodizedAlMMC.
简介:AferromagneticamorphousFe73Al4Ge2Nb1P10C6B4alloywithhighglass-formingabilitywassynthesizedbymeltspinning.Thesupercooledliquidregionbeforecrystallizationreachesabout65.7K.Thecrystallizedstructureconsistsofα-Fe,Fe3B,FeB,Fe3PandFe3Cphases.TheFebasedamorphousalloyexhibitsgoodmagneticpropertieswithahighsaturationmagnetizationandalowsaturatedmagnetostriction.Thecrystallizationleadstoanobviousdecreaseinthesoftmagneticproperties.
简介:Thehydrodynamicdeepdrawingprocessenablesnetshapeornearnetshapeformingofcomplicatedsheetmetalpartsmadefromdifficultlyformingmaterials,suchasaluminiumorhighstrengthsteels.Basedontheconventionalhydrodynamicdeepdrawingprocess,anewprocess,hydrodynamicdeepdrawingprocess,inwhichradialpressureisappliedtotherimoftheblank,isproposed.ThisnewprocesshasbeenanalysedusingFEMsimulationsandtheobtainedresultshavebeencomparedwiththeexperimentalresults.ThematerialusedintheexperimentswasAl-Mg-Sialloy,andintheFEM-simulationstheelastic-plasticbehaviourofAl-Mg-SialloywasmodelledusingBarlat's89yieldcriteria.
简介:这篇论文试图基于充分温度地,集中地和速度地联合与模仿微观结构形成微动力学。作者介绍了一个新方法,它是频分多路复用和细胞的自动机(CAFD)的联合设想片由真空投资过程扔了的薄复杂超级合金汽轮机的微观结构形成。异构的成核的分发,取向和机制,树突的生长动力学并且对equiaxed转变(CET)圆柱被考虑。利用这些模仿的计划,谷物的规模和一致性上的关键进程变量的全面影响被调查了份量上。模仿的谷物尺寸和形态学与试验性的结果同意很好。