【英文标准名称】:StandardTestMethodforKnoopIndentationHardnessofAdvancedCeramics
【原文标准名称】:高级陶瓷的努氏压痕硬度的标准试验方法
【标准号】:ASTMC1326-2008e1
【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】:C28.01
【标准类型】:(TestMethod)
【标准水平】:()
【中文主题词】:
【英文主题词】:advancedceramics;indentation;Knoophardness;microscope;Advancedceramics;Hardness(indentation);Knoophardness(HK)number;Microscopicexamination--advancedceramics;Opticalmicroscopy
【摘要】:Foradvancedceramics,Knoopindentersareusedtocreateindentations.Thesurfaceprojectionofthelongdiagonalismeasuredwithopticalmicroscopes.TheKnoopindentationhardnessisoneofmanypropertiesthatisusedtocharacterizeadvancedceramics.AttemptshavebeenmadetorelateKnoopindentationhardnesstootherhardnessscales,butnogenerallyacceptedmethodsareavailable.Suchconversionsarelimitedinscopeandshouldbeusedwithcaution,exceptforspecialcaseswhereareliablebasisfortheconversionhasbeenobtainedbycomparisontests.Foradvancedceramics,theKnoopindentationisoftenpreferredtotheVickersindentationsincetheKnooplongdiagonallengthis2.8timeslongerthantheVickersdiagonalforthesameload,andcrackingismuchlessofaproblem(1).Ontheotherhand,thelongslendertipoftheKnoopindentationismoredifficulttopreciselydiscern,especiallyinmaterialswithlowcontrast.Theindentationloadschoseninthistestmethodaredesignedtoproduceindentationsaslargeasmaybepossiblewithconventionalmicrohardnessequipment,yetnotsolargeastocausecracking.TheKnoopindentationisshallowerthanVickersindentationsmadeatthesameload.Knoopindentsmaybeusefulinevaluatingcoatinghardnesses.Knoophardnessiscalculatedfromtheratiooftheappliedloaddividedbytheprojectedindentationareaonthespecimensurface.Itisassumedthattheelasticspringbackofthenarrowdiagonalisnegligible.(Vickersindentersarealsousedtomeasurehardness,butVickershardnessiscalculatedfromtheratioofappliedloadtotheareaofcontactofthefourfacesoftheundeformedindenter.)Afullhardnesscharacterizationincludesmeasurementsoverabroadrangeofindentationloads.Knoophardnessofceramicsusuallydecreaseswithincreasingindentationsizeorindentationforce(load).Thetrendisknownastheindentationsizeeffect(ISE).Hardnessapproachesaplateauconstanthardnessatsufficientlylargeindentationsizeorforces(loads).Thetestforcesorloadsthatareneededtoachieveaconstanthardnessvarywiththeceramic.Thetestforcespecifiedinthisstandardisintendedtobesufficientlylargethathardnessiseitherclosetoorontheplateau,butnotsolargeastointroduceexcessivecracking.AcomprehensivecharacterizationoftheISEisrecommendedbutisbeyondthescopeofthistestmethodwhichmeasureshardnessatasingle,designatedload.1.1ThistestmethodcoversthedeterminationoftheKnoopindentationhardnessofadvancedceramics.1.2ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregulatorylimitationspriortouse.
【中国标准分类号】:Q32
【国际标准分类号】:81_060_99
【页数】:9P.;A4
【正文语种】:英语