1、Licensed Copy: Wang Bin, ISO/Exchange China Standards Information Centre, 09 September 2003, Uncontrolled Copy, (c) BSIBRITISH STANDARD BS EN 12789:2002 Advanced technical ceramics Mechanical properties of ceramic composites at high temperature under air at atmospheric pressure Determination of flex
2、ural strength The European Standard EN 12789:2002 has the status of a British Standard ICS 81.060.30 Licensed Copy: Wang Bin, ISO/Exchange China Standards Information Centre, 09 September 2003, Uncontrolled Copy, (c) BSIBS EN 12789:2002 This British Standard was published under the authority of the
3、Standards Policy and Strategy Committee on 17 April 2003 BSI 17 April 2003 ISBN 0 580 41587 2 National foreword This British Standard is the official English language version of EN 12789:2002. It supersedes DD ENV 12789:1998 which is withdrawn. The UK participation in its preparation was entrusted t
4、o Technical Committee RPI/13, Advanced technical ceramics, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in
5、this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a
6、contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposa
7、ls for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 13 and a back cover. The BSI copyright date displayed
8、 in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments Licensed Copy: Wang Bin, ISO/Exchange China Standards Information Centre, 09 September 2003, Uncontrolled Copy, (c) BSIEUROPEANSTANDARD NORMEEUROPENNE EUROPISCHENORM EN12789 Octo
9、ber2002 ICS81.060.30 SupersedesENV12789:1998 Englishversion AdvancedtechnicalceramicsMechanicalpropertiesofceramic compositesathightemperatureunderairatatmospheric pressureDeterminationofflexuralstrength CramiquestechniquesavancesPropritsmcaniques descramiquescompositeshautetempraturesousair pressio
10、natmosphriqueDterminationdelarsistance enflexion HochleistungskeramikMechanischeEigenschaftenvon keramischenVerbundwerkstoffenbeihoherTemperaturau LuftbeiAtmosphrendruckBestimmunngder Beigefestigkeit ThisEuropeanStandardwasapprovedbyCENon7September2002. CENmembersareboundtocomplywiththeCEN/CENELECIn
11、ternalRegulationswhichstipulatetheconditionsforgivingthisEurope an Standardthestatusofanationalstandardwithoutanyalteration.Uptodatelistsandbibliographicalreferencesconcernings uchnational standardsmaybeobtainedonapplicationtotheManagementCentreortoanyCENmember. ThisEuropeanStandardexistsinthreeoffi
12、cialversions(English,French,German).Aversioninanyotherlanguagemadebytra nslation undertheresponsibilityofaCENmemberintoitsownlanguageandnotifiedtotheManagementCentrehasthesamestatusasthe official versions. CENmembersarethenationalstandardsbodiesofAustria,Belgium,CzechRepublic,Denmark,Finland,France,
13、Germany,Greece, Iceland,Ireland,Italy,Luxembourg,Malta,Netherlands,Norway,Portugal,Spain,Sweden,SwitzerlandandUnitedKingdom. EUROPEANCOMMITTEEFORSTANDARDIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre:ruedeStassart,36B1050Brussels 2002CEN Allrightsofexploitationinany
14、formandbyanymeansreserved worldwideforCENnationalMembers. Ref.No.EN12789:2002E Licensed Copy: Wang Bin, ISO/Exchange China Standards Information Centre, 09 September 2003, Uncontrolled Copy, (c) BSIEN12789:2002(E) 2 Contents page Foreword3 1 Scope 4 2 Normativereferences 4 3 Principle4 4 Termsanddef
15、initions. .4 5 Apparatus .5 5.1 Testmachine 5 5.2 Testjig .5 5.3 Setupforheating 5 5.4 Temperaturemeasurement. 6 5.5 Datarecordingsystem . .6 5.6 Micrometers6 6 Testpieces. .6 7 Testpiecepreparation .7 7.1 Machiningandpreparation. 7 7.2 Numberoftestpieces . 7 8 Testprocedures . 7 8.1 Testsetup:tempe
16、ratureconsiderations . .7 8.2 Testsetup:otherconsiderations. .8 8.3 Testingtechnique . .8 8.4 Testvalidity . .9 9 Calculationofresults 9 9.1 Testpieceorigin. 9 9.2 Flexuralstrength. .9 10 Testreport 11 Bibliography 13 Licensed Copy: Wang Bin, ISO/Exchange China Standards Information Centre, 09 Septe
17、mber 2003, Uncontrolled Copy, (c) BSIEN12789:2002(E) 3 Foreword Thisdocument(EN12789:2002)hasbeenpreparedbyTechnicalCommitteeCEN/TC184“Advancedtechnical ceramics“,thesecretariatofwhichisheldbyBSI. ThisEuropeanStandardshallbegiventhestatusofanationalstandard,eitherbypublicationofanidenticaltextor bye
18、ndorsement,atthelatestbyApril2003,andconflictingnationalstandardsshallbewithdrawnatthelatestby April2003. ThisdocumentsupersedesENV12789:1998. AccordingtotheCEN/CENELECInternalRegulations,thenationalstandardsorganizationsofthefollowing countriesareboundtoimplementthisEuropeanStandard:Austria,Belgium
19、,CzechRepublic,Denmark,Finland, France,Germany,Greece,Iceland,Ireland,Italy,Luxembourg,Malta,Netherlands,Norway,Portugal,Spain, Sweden,SwitzerlandandtheUnitedKingdom. Licensed Copy: Wang Bin, ISO/Exchange China Standards Information Centre, 09 September 2003, Uncontrolled Copy, (c) BSIEN12789:2002(E
20、) 4 1Scope ThisEuropeanStandardspecifiestheconditionsfordeterminationoftheflexuralstrengthofceramicmatrix compositematerialswithcontinuousfibrereinforcementunderthreepointorfourpointbendingfortemperatures upto1700Cinairatatmosphericpressure. Thisstandardappliestoallceramicmatrixcompositeswithacontin
21、uousfibrereinforcement,unidirectional(1D), bidirectional(2D),andtridirectional(xD,with2x3),loadedalongoneprincipalaxisofreinforcement. NOTE1 Inmostcases,ceramicmatrixcompositestobeusedathightemperatureinairarecoatedwithanantioxidation coating. NOTE2 Thepurposeofthisstandardistodeterminetheflexuralst
22、rengthofamaterialunderanoxidizingenvironmentbut nottomeasurematerialoxidation. 2 Normativereferences ThisEuropeanStandardincorporatesbydatedorundatedreference,provisionsfromotherpublications.These normativereferencesarecitedattheappropriateplacesinthetext,andthepublicationsarelistedhereafter.For dat
23、edreferences,subsequentamendmentstoorrevisionsofanyofthesepublicationsapplytothisEuropean Standardonlywhenincorporatedinitbyamendmentorrevision.Forundatedreferencesthelatesteditionofthe publicationreferredtoapplies(includingamendments). ENISO75001, MetallicmaterialsVerificationofstaticuniaxialtestin
24、gmachinesPart1:Tension/compression testingmachines(ISO75001:1999) . EN605841, ThermocouplesPart1:Referencetables.(IEC605841:1995) . EN605842, ThermocouplesPart2:Tolerances .(IEC605842:1982+A1:1989) . ISO3611, Micrometercallipersforexternalmeasurement. 3Principle Atestpieceofspecifieddimensionsisheat
25、edtothetestingtemperature.Itissubsequentlyloadedinflexureto fractureinsuchawaythatfailureoccursintensionorincompressionalongoneprincipalaxisofreinforcement. Thetestisperformedatconstantcrossheaddisplacementrate. Thetestdurationislimitedtoreduceanytimedependenteffects(creep,etc.). 4 Termsanddefinitio
26、ns ForthepurposesofthisEuropeanStandard,thefollowingtermsanddefinitionsapply. 4.1 testtemperature, T temperatureatthecentreofthetestpiece 4.2 maximumflexuralforce, F m highestrecordedforceinaflexuraltestonthetestpiecewhentestedtofailure Licensed Copy: Wang Bin, ISO/Exchange China Standards Informati
27、on Centre, 09 September 2003, Uncontrolled Copy, (c) BSIEN12789:2002(E) 5 4.3 flexuralstress, ss thenominalstressontheoutersurfaceofthetestpiece,calculatedatmidspan NOTE Thisstressisconventionallycalculatedaccordingtothesimplebeamtheory,whosebasicassumptionscannotbe metbyceramicmatrixcompositemateri
28、als. 4.4 flexuralstrength, ss f,m maximumflexuralstressappliedtoatestpiecethatfracturesduringaflexuraltest twoflexuralstrengthscanbedistinguished: apparentflexuralstrength, s f,m,a ,whentheapparentdimensionsareused effectiveflexuralstrength, s f,m,e ,whenthedimensionsarecorrectedbyafactortoaccountfo
29、rthepresence oftheantioxidativeprotection 5Apparatus 5.1 Testmachine Themachineshallbeequippedwithasystemformeasuringtheforceappliedtothetestpiece.Thesystemshall conformtograde1accordingtoENISO75001. 5.2 Testjig Thetestjigiscomposedoftwoparts,linkedtothefixedandmobilepartsofthemachine.Ithastwoouters
30、upport rollersandone(threepointbending)ortwo(fourpointbending)innersupportrollers. Thematerialofthejigandthatoftherollersshallnotreactwiththatofthespecimen,norwiththeenvironment. Thecylindricalrollersshallhaveadiameterof4mmto10mm.Theirlengthshallbeatleastequaltothewidthof thespecimen.Theyshallbemade
31、ofamaterialwithahardnessatleastequaltothatofthespecimen.Theaxesof therollersshallbeparalleltowithin0,01mm/mm. Theouterrollers(threeandfourpointbending)andinnerrollers(fourpointbending)shallbefreetorotate(see Figure1). Eithertwoorthreerollers,forthreepointorfourpointbendingrespectively,shallbefreetop
32、ivotaroundanaxis paralleltothelongitudinaldirectionofthetestpiece,inordertoadapttothenonparallelismoftheupperandlower facesofunmachinedtestpieces(seeFigure1). Therollingandpivotingabilityoftherollersshallnotbeaffectedbyheating.Thedistancebetweenrollersshallbe inaccordancetoclause6. Theinnerroller(s)
33、shallbecentredwithrespecttotheouterrollerstowithin0,2mm.Inthecaseoffourpoint bendingalevellingsystemshallbeusedtoensuresymmetricalloadingofthetestpiece. Theperformanceshallnotchangebecauseofheating. 5.3 Setupforheating Thesetupforheatingshallbeconstructedinsuchawaythatthevariationoftemperatureofpart
34、ofthetestpiece whichisbetweentheoutersupportrollersislessthan50Cattesttemperature. Licensed Copy: Wang Bin, ISO/Exchange China Standards Information Centre, 09 September 2003, Uncontrolled Copy, (c) BSIEN12789:2002(E) 6 5.4Temperature measurement ThermocouplesshallcomplywithEN605841andEN605842.Alter
35、natively,pyrometersorthermocoupleswhich arenotcoveredbyEN605841andEN605842,butwhichareappropriatelycalibratedcanbeused. 5.5 Datarecordingsystem Acalibratedrecordershallbeusedtorecordforcetimecurve.Theuseofadigitaldatarecordingsystemcombined withananaloguerecorderisrecommended. 5.6Micrometers Microme
36、tersusedforthemeasurementofthedimensionsofthetestpieceshallbeinaccordancewithISO3611. 6 Testpieces RecommendedspecimendimensionsaregiveninTable1.Thesedimensionshavebeensuccessfullyusedand takedueaccountofthefollowingfactors: Theamountofmaterialunderloadshallberepresentativeofthenatureofthematerialan
37、dofthereinforcement structure.Thissetsminimumlimitstothespanandtothewidthandthicknessofthespecimen.Inthecaseof flexural,asopposedtotensiletesting,alsothedistributionofthelongitudinalreinforcementthroughthethickness hastobeconsidered.Whenthisdistributionisnotsymmetricalwithrespecttotheneutralplane,ca
38、reshallbe takentoinsurethatitissimilarbetweenspecimens. Thethicknessandthedistancebetweentheinnerandouterroller(s)shallbechosensoastoavoidshearfailure. Thisisachievedbysettingaminimumlimittotheratiobetweenthemomentarmandthespecimenthickness.A valueof10iscommonlyusedandtranslatesintoaminimumL/hratioo
39、f20inthreepointbending,andaminimum (LLi)/hratioof20infourpointbendingwithLi=L/3. Otherfactorsaffectingthesizeanddimensionsofthespecimensarethetypeoftheheatingandoftheloading system. Table1Recommendedtestspecimenandspandimensions Dimensionsinmillimetres 1D,2D&xD Tolerance L t ,totallength L+10 +1 b,w
40、idth 10 +0,2 h,thickness 2,5 +0,2 Innerspan fourpointbending,L i 25 +0,1 Outerspan fourpointbending,L 75 +0,1 threepointbending,L 50 +0,1 NOTE Ifitisnecessarytodefinetestpiecesofdifferentdimensions,theconditionsofclause6shouldbetakeninto account. Licensed Copy: Wang Bin, ISO/Exchange China Standards
41、 Information Centre, 09 September 2003, Uncontrolled Copy, (c) BSIEN12789:2002(E) 7 7 Testpiecepreparation 7.1 Machiningandpreparation Duringcuttingout,careshallbetakentoalignthelongitudinaltestpieceaxiswithoneoftheprincipalaxesof reinforcement. Specimensmaybetestedwitheithermachinedornonmachinedtop
42、andbottomsurfaces.Insomecases machiningisnotrecommendedbecauseitmaycausebreakageofthefibresnearthetopandbottomsurfacesas wellasdamagetotheantioxidationcoatingifpresent.Whenmachiningthesesurfaces,careshallbetakento maintainareinforcementgeometryacrossthethicknessofthespecimen,whichisrepresentativeoft
43、hematerialin theasprocessedcondition.Inparticular,itshallbeassuredthatthesymmetryofanoriginallysymmetric reinforcementgeometryispreservedinthespecimencrosssectionaftermachining. Machiningparameterswhichavoiddamagetothematerialshallbeestablishedanddocumented.These parametersshallbeadheredtoduringtest
44、piecepreparation. NOTE Whenspecimensaremachinedfromaplatewhichhasbeenprotectedagainstoxidation,thecutsurfacesofthe specimenareunprotected.Thesesurfacesshouldbeprotectedtopreventoxidation. 7.2 Numberoftestpieces Atleastfivevalidtestresults,asspecifiedinparagraph8.4arerequiredperloadingcondition.Forspecimenswith anonsymmetricreinforcementgeome
