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【英文标准名称】:StandardTestMethodforFlexuralStrengthofAdvancedCeramicsatElevatedTemperatures
【原文标准名称】:高温下高级陶瓷抗弯强度的标准试验方法
【标准号】:ASTMC1211-2002(2008)
【标准状态】:现行
【国别】:美国
【发布日期】:2002
【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】:C28.01
【标准类型】:(TestMethod)
【标准水平】:()
【中文主题词】:
【英文主题词】:elevatedtemperature;flexuralstrength;four-pointflexure;three-pointflexure;Advancedceramics;Flexuraltesting--ceramics;Loadingtests--ceramics
【摘要】:Thistestmethodmaybeusedformaterialdevelopment,qualitycontrol,characterization,anddesigndatagenerationpurposes.Thistestmethodisintendedtobeusedwithceramicswhoseflexuralstrengthis8764;50MPa(8764;7ksi)orgreater.Theflexurestressiscomputedbasedonsimplebeamtheory,withassumptionsthatthematerialisisotropicandhomogeneous,themoduliofelasticityintensionandcompressionareidentical,andthematerialislinearlyelastic.Theaveragegrainsizeshouldbenogreaterthan1/50ofthebeamthickness.Thehomogeneityandisotropyassumptionsinthetestmethodruleouttheuseofitforcontinuousfiber-reinforcedcompositesforwhichTestMethodC1341ismoreappropriate.Theflexuralstrengthofagroupoftestspecimensisinfluencedbyseveralparametersassociatedwiththetestprocedure.Suchfactorsincludethetestingrate,testenvironment,specimensize,specimenpreparation,andtestfixtures.SpecimenandfixturesizeswerechosentoprovideabalancebetweenthepracticalconfigurationsandresultingerrorsasdiscussedinMIL-STD1942(A),TestMethodC1161,andRefs(1x2013;3).SpecificfixtureandspecimenconfigurationsweredesignatedinordertopermitthereadycomparisonofdatawithouttheneedforWeibullsizescaling.Theflexuralstrengthofaceramicmaterialisdependentonbothitsinherentresistancetofractureandthesizeandseverityofflaws.Variationsinthesecauseanaturalscatterintestresultsforasampleoftestspecimens.Fractographicanalysisoffracturesurfaces,althoughbeyondthescopeofthistestmethod,ishighlyrecommendedforallpurposes,especiallyifthedatawillbeusedfordesignasdiscussedinMILSTD1942(A)andRef(4)andPracticesC1322andC1239.Thismethoddeterminestheflexuralstrengthatelevatedtemperatureandambientenvironmentalconditionsatanominal,moderatelyfasttestingrate.Theflexuralstrengthundertheseconditionsmayormaynotnecessarilybetheinertflexuralstrength.Flexurestrengthatelevatedtemperaturemaybestronglydependentontestingrate,aconsequenceofcreep,stresscorrosion,orslowcrackgrowth.Ifthepurposeofthetestistomeasuretheinertflexuralstrength,thenextraprecautionsarerequiredandfastertestingratesmaybenecessary.Note68212;Manyceramicsaresusceptibletoeitherenvironmentally-assistedslowcrackgrowthorthermallyactivatedslowcrackgrowth.Oxideceramics,glasses,glassceramics,andceramicscontainingboundaryphaseglassareparticularlysusceptibletoslowcrackgrowth.Timedependenteffectsthatarecausedbyenvironmentalfactors(e.g.waterashumidityinair)maybeminimizedthroughtheuseofinerttestingatmospheresuchasdrynitrogengasorvacuum.Alternatively,testingratesfasterthanspecifiedinthisstandardmaybeusedifthegoalistomeasuretheinertstrength.Thermallyactivatedslowcrackgrowthmayoccuratelevatedtemperatureevenininertatmospheres.Testingratesfasterthanspecifiedinthisstandardshouldbeusedifthegoalistomeasuretheinertflexuralstrength.Ontheotherhand,manyceramicssuchasboroncarbide,siliconcarbide,aluminumnitrideandmanysiliconnitrideshavenosensitivitytoslowcrackgrowthatroomormoderatelyelevatedtemperaturesandforsuchmaterials,theflexuralstrengthmeasuredunderinlaboratoryambientconditionsatthenominaltestingrateistheinertflexuralstrength.Thethree-pointtestconfigurationexposesonlyaverysmallportion..........
【中国标准分类号】:Q32
【国际标准分类号】:81_060_30
【页数】:17P.;A4
【正文语种】:英语