SIST EN 12789:2004

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Advanced technical ceramics - Mechanical properties of ceramic composites at high temperature under air at atmospheric pressure - Determination of flexural strengthHochleistungskeramik - Mechanische Eigenschaften von keramischen Verbundwerkstoffen bei hoher Temperatur au Luft bei Atmosphärendruck - Bestimmunng der BeigefestigkeitCéramiques techniques avancées - Propriétés mécaniques des céramiques composites a haute température sous air a pression atmosphérique - Détermination de la résistance en flexionAdvanced technical ceramics - Mechanical properties of ceramic composites at high temperature under air at atmospheric pressure - Determination of flexural strength81.060.30Sodobna keramikaAdvanced ceramicsICS:Ta slovenski standard je istoveten z:EN 12789:2002SIST EN 12789:2004en01-januar-2004SIST EN 12789:2004SLOVENSKI
STANDARDSIST ENV 12789:20001DGRPHãþD



SIST EN 12789:2004



EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 12789October 2002ICS 81.060.30Supersedes ENV 12789:1998English versionAdvanced technical ceramics - Mechanical properties of ceramiccomposites at high temperature under air at atmosphericpressure - Determination of flexural strengthCéramiques techniques avancées - Propriétés mécaniquesdes céramiques composites à haute température sous air àpression atmosphérique - Détermination de la résistanceen flexionHochleistungskeramik - Mechanische Eigenschaften vonkeramischen Verbundwerkstoffen bei hoher Temperatur auLuft bei Atmosphärendruck - Bestimmunng derBeigefestigkeitThis European Standard was approved by CEN on 7 September 2002.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Management Centre or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2002 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 12789:2002 ESIST EN 12789:2004



EN 12789:2002 (E)2ContentspageForeword.31Scope.42Normative references.43Principle.44Terms and definitions.45Apparatus.55.1Test machine.55.2Test jig.55.3Set-up for heating.55.4Temperature measurement.65.5Data recording system.65.6Micrometers.66Test pieces.67Test piece preparation.77.1Machining and preparation.77.2Number of test pieces.78Test procedures.78.1Test set-up: temperature considerations.78.2Test set-up: other considerations.88.3Testing technique.88.4Test validity.99Calculation of results.99.1Test piece origin.99.2Flexural strength.910Test report.11Bibliography.13SIST EN 12789:2004



EN 12789:2002 (E)3ForewordThis document (EN 12789:2002) has been prepared by Technical Committee CEN /TC 184 "Advanced technicalceramics", the secretariat of which is held by BSI.This European Standard shall be given the status of a national standard, either by publication of an identical text orby endorsement, at the latest by April 2003, and conflicting national standards shall be withdrawn at the latest byApril 2003.This document supersedes ENV 12789:1998.According to the CEN/CENELEC Internal Regulations, the national standards organizations of the followingcountries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland,France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain,Sweden, Switzerland and the United Kingdom.SIST EN 12789:2004



EN 12789:2002 (E)41 ScopeThis European Standard specifies the conditions for determination of the flexural strength of ceramic matrixcomposite materials with continuous fibre reinforcement under three-point or four-point bending for temperaturesup to 1 700 °C in air at atmospheric pressure.This standard applies to all ceramic matrix composites with a continuous fibre reinforcement, unidirectional (1D),bidirectional (2D), and tridirectional (xD, with 2 < x < 3), loaded along one principal axis of reinforcement.NOTE 1In most cases, ceramic matrix composites to be used at high temperature in air are coated with an antioxidationcoating.NOTE 2The purpose of this standard is to determine the flexural strength of a material under an oxidizing environment butnot to measure material oxidation.2 Normative referencesThis European Standard incorporates by dated or undated reference, provisions from other publications. Thesenormative references are cited at the appropriate places in the text, and the publications are listed hereafter. Fordated references, subsequent amendments to or revisions of any of these publications apply to this EuropeanStandard only when incorporated in it by amendment or revision. For undated references the latest edition of thepublication referred to applies (including amendments).EN ISO 7500-1, Metallic materials - Verification of static uniaxial testing machines - Part 1: Tension/compressiontesting machines (ISO 7500-1:1999).EN 60584-1, Thermocouples - Part 1: Reference tables. (IEC 60584-1:1995).EN 60584-2, Thermocouples - Part 2: Tolerances. (IEC 60584-2:1982 + A1:1989).ISO 3611, Micrometer callipers for external measurement.3 PrincipleA test piece of specified dimensions is heated to the testing temperature. It is subsequently loaded in flexure tofracture in such a way that failure occurs in tension or in compression along one principal axis of reinforcement.The test is performed at constant crosshead displacement rate.The test duration is limited to reduce any time dependent effects (creep, etc.).4 Terms and definitionsFor the purposes of this European Standard, the following terms and definitions apply.4.1test temperature, Ttemperature at the centre of the test piece4.2maximum flexural force, Fmhighest recorded force in a flexural test on the test piece when tested to failureSIST EN 12789:2004



EN 12789:2002 (E)54.3flexural stress, ssthe nominal stress on the outer surface of the test piece, calculated at mid-spanNOTEThis stress is conventionally calculated according to the simple beam theory, whose basic assumptions cannot bemet by ceramic matrix composite materials.4.4flexural strength, ssf,mmaximum flexural stress applied to a test piece that fractures during a flexural testtwo flexural strengths can be distinguished:¾ apparent flexural strength, sf,m,a, when the apparent dimensions are used¾ effective flexural strength, sf,m,e, when the dimensions are corrected by a factor to account for the presenceof the antioxidative protection5 Apparatus5.1 Test machineThe machine shall be equipped with a system for measuring the force applied to the test piece. The system shallconform to grade 1 according to EN ISO 7500-1.5.2 Test jigThe test jig is composed of two parts, linked to the fixed and mobile parts of the machine. It has two outer supportrollers and one (three-point bending) or two (four-point bending) inner support rollers.The material of the jig and that of the rollers shall not react with that of the specimen, nor with the environment.The cylindrical rollers shall have a diameter of 4 mm to 10 mm. Their length shall be at least equal to the width ofthe specimen. They shall be made of a material with a hardness at least equal to that of the specimen. The axes ofthe rollers shall be parallel to within 0,01 mm/mm.The outer rollers (three and four-point bending) and inner rollers (four-point bending) shall be free to rotate (seeFigure 1).Either two or three rollers, for three-point or four-point bending respectively, shall be free to pivot around an axisparallel to the longitudinal direction of the test piece, in order to adapt to the non-parallelism of the upper and lowerfaces of unmachined test pieces(see Figure 1).The rolling and pivoting ability of the rollers shall not be affected by heating. The distance between rollers shall bein accordance to clause 6.The inner roller(s) shall be centred with respect to the outer rollers to with
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