ASTM C1674-2008 环境温度下带工业孔隙(蜂窝状孔道)的高级陶瓷抗挠强度的标准试验方法

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【英文标准名称】:StandardTestMethodforFlexuralStrengthofAdvancedCeramicswithEngineeredPorosity(HoneycombCellularChannels)atAmbientTemperatures
【原文标准名称】:环境温度下带工业孔隙(蜂窝状孔道)的高级陶瓷抗挠强度的标准试验方法
【标准号】:ASTMC1674-2008
【标准状态】:现行
【国别】:美国
【发布日期】:2008
【实施或试行日期】:
【发布单位】:美国材料与试验协会(US-ASTM)
【起草单位】:C28.04
【标准类型】:(TestMethod)
【标准水平】:()
【中文主题词】:
【英文主题词】:advancedceramics;catalysts;cellularstructure;filters;flexuralstrength;four-pointflexure;honeycomb;honeycombstructurestrength;nominalbeamstrength;porosity;three-pointflexure;wallfracturestrength
【摘要】:Thistestmethodisusedtodeterminethemechanicalpropertiesinflexureofengineeredceramiccomponentswithmultiplelongitudinalhollowchannels,commonlydescribedasx201C;honeycombx201D;channelarchitectures.Thecomponentsgenerallyhave30%ormoreporosityandthecross-sectionaldimensionsofthehoneycombchannelsareontheorderof1millimeterorgreater.Theexperimentaldataandcalculatedstrengthvaluesfromthistestmethodareusedformaterialandstructuraldevelopment,productcharacterization,designdata,qualitycontrol,andengineering/productionspecifications.Note18212;Flexuretestingisthepreferredmethodfordeterminingthenominalx201C;tensilefracturex201D;strengthofthesecomponents,ascomparedtoacompression(crushing)test.Anominaltensilestrengthisrequired,becausethesematerialscommonlyfailintensionunderthermalgradientstresses.Atruetensiletestisdifficulttoperformonthesehoneycombspecimensbecauseofgrippingandalignmentchallenges.Themechanicalpropertiesdeterminedbythistestmethodarebothmaterialandarchitecturedependent,becausethemechanicalresponseandstrengthoftheporoustestspecimensaredeterminedbyacombinationofinherentmaterialpropertiesandmicrostructureandthearchitectureofthechannelporosity[porosityfraction/relativedensity,channelgeometry(shape,dimensions,cellwallthickness,etc.),anisotropyanduniformity,etc.]inthespecimen.Comparisonoftestdatamustconsiderbothdifferencesinmaterial/compositionpropertiesaswellasdifferencesinchannelporosityarchitecturebetweenindividualspecimensanddifferencesbetweenandwithinspecimenlots.TestMethodAisauser-definedspecimengeometrywithachoiceoffour-pointorthree-pointflexuretestinggeometries.Itisnotpossibletodefineasinglefixedspecimengeometryforflexuretestingofhoneycombs,becauseofthewiderangeofhoneycombarchitecturesandcellsizesandconsiderationsofspecimensize,cellshapes,pitch,porositysize,crushstrength,andshearstrength.Asageneralrule,theexperimenterwillhavetodefineasuitabletestspecimengeometryfortheparticularhoneycombstructureofinterest,consideringcomposition,architecture,cellsize,mechanicalproperties,andspecimenlimitationsandusingthefollowingguidelines.Detailsonspecimengeometrydefinitionaregiveninsection9.2.Four-pointflexure(TestMethodA1)isstronglypreferredandrecommendedfortestingandcharacterizationpurposes.(FromTestMethodC1161section4.5:x201C;Thethree-pointtestconfigurationexposesonlyaverysmallportionofthespecimentothemaximumstress.Therefore,three-pointflexuralstrengthsarelikelytobemuchgreaterthanfour-pointflexuralstrengths.Three-pointflexurehassomeadvantages.Itusessimplertestfixtures,itiseasiertoadapttohightemperatureandfracturetoughnesstesting,anditissometimeshelpfulinWeibullstatisticalstudies.However,four-pointflexureispreferredandrecommendedformostcharacterizationpurposes.x201D;)Thethree-pointflexuretestconfiguration(TestMethodA2)maybeusedforspecimenswhicharenotsuitablefor4-pointtesting,withtheclearunderstandingthat3-pointloadingexposesonlyaverysmallportionofthespecimentothemaximumstress,ascomparedtothemuchlargermaximumstressvolumeina4-pointloadingconfiguration.Therefore,3-pointflexuralstrengthsarelikelytobegreaterthan4-pointflexuralstrengths,basedonstatisticalflawdistributionfactors.TestMethodB(withaspecifiedspecimen......