1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58composites at high temperature under inert atmosphere Determination of creep behaviourThe European
2、Standard EN 13235:2006 has the status of a British StandardICS 81.060.30Advanced technical ceramics Mechanical properties of ceramic BRITISH STANDARDBS EN 13235:2006BS EN 13235:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 29 December 2
3、006 BSI 2006ISBN 0 580 49863 8Amendments issued since publicationAmd. No. Date Commentscontract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.National forewordThis British Standard was published by BSI. It is the U
4、K implementation of EN 13235:2006. It supersedes DD ENV 13235:2000 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee RPI/13, Advanced technical ceramics.A list of organizations represented on RPI/13 can be obtained on request to its secretary.This publi
5、cation does not purport to include all the necessary provisions of a EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 13235October 2006ICS 81.060.30 Supersedes ENV 13235:1998 English VersionAdvanced technical ceramics - Mechanical properties of ceramiccomposites at high temperature under inert atmo
6、sphere -Determination of creep behaviourCramiques techniques avances - Proprits mcaniquesdes cramiques composites haute temprature sousatmosphre inerte - Dtermination du comportement aufluageHochleistungskeramik - Mechanische Eigenschaften vonkeramischen Verbundwerkstoffen bei hoher Temperatur inine
7、rter Atmosphre - Bestimmung des KriechverhaltensThis European Standard was approved by CEN on 10 September 2006.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 alte
8、ration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by transla
9、tionunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary
10、, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue d
11、e Stassart, 36 B-1050 Brussels 2006 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 13235:2006: EEN 13235:2006 (E) 2 Contents Page Foreword. 3 1 Scope 4 2 Normative references . 4 3 Principle . 4 4 Terms, definitions and symbols 5 5
12、Significance and use 6 6 Apparatus 7 6.1 Test installations. 7 6.2 Load train. 7 6.3 Test chamber. 8 6.4 Set-up for heating . 8 6.5 Extensometer 8 6.6 Temperature measurement 9 6.7 Data recording system . 9 6.8 Micrometers. 9 7 Test specimens . 9 8 Test specimen preparation 10 8.1 Machining and prep
13、aration 10 8.2 Number of test specimens . 10 9 Test procedures 10 9.1 Test set-up: temperature considerations .10 9.2 Test set-up: loading considerations . 11 9.3 Test set-up: measurement of test specimen dimensions. 11 9.4 Test technique. 11 9.5 Test validity . 13 10 Calculation of results 14 10.1
14、Test specimen origin 14 10.2 Results . 14 10.3 Creep strain rate curve. 15 11 Test report . 15 EN 13235:2006 (E) 3 Foreword This document (EN 13235:2006) has been prepared by Technical Committee CEN/TC 184 “Advanced technical ceramics”, the secretariat of which is held by BSI. This European Standard
15、 shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by April 2007, and conflicting national standards shall be withdrawn at the latest by April 2007. This document supersedes ENV 13235:1998. ENV 13235 was approved by CEN/TC 1
16、84 for development into a full European Standard. The principal changes to the ENV are in the normative references, as follows: - in 6.1.1, reference to EN 10002-2 has been replaced by reference to EN ISO 7500-1; - in 6.2, reference to WI 136 has been removed; - references to ENV 1892 have been repl
17、aced by references to EN 1892. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Icel
18、and, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 13235:2006 (E) 4 1 Scope This European Standard specifies the conditions for the determination of the tensile creep deforma
19、tion and failure behaviour of ceramic matrix composite materials with continuous fibre reinforcement for temperatures up to 2 000 C under vacuum or in a gas atmosphere which is inert to the material under test. The purpose of these test conditions is to prevent changes to the material as a result of
20、 chemical reaction with the test environment. This European Standard applies to all ceramic matrix composites with a continuous fibre reinforcement, unidirectional (1 D), bidirectional (2 D), and tridirectional (x D, where 2 x 3), loaded along one principal axis of reinforcement. 2 Normative referen
21、ces The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 1892, Advanced technical ceramics Mechanic
22、al properties of ceramic composites at high temperature under inert atmosphere Determination of tensile properties 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) EN ISO 7500-1, Metallic materials Verific
23、ation of static uniaxial testing machines Part 1: Tension/compression testing machines Verification and calibration of the force-measuring system (ISO 7500-1:2004) ISO 3611, Micrometer callipers for external measurement 3 Principle A test specimen of specified dimensions is heated to the test temper
24、ature, and loaded under tension to a specified level of force. This force is maintained at a constant level for a specified time or until rupture. The variation in gauge length is recorded in relation to time. EN 13235:2006 (E) 5 4 Terms, definitions and symbols For the purposes of this document, th
25、e following terms, definitions and symbols apply. 4.1 creep total time-dependent increase of gauge length starting from the time when the constant specified level of force is reached 4.2 test temperature, T temperature of the test specimen at the centre of the gauge length 4.3 calibrated length, l p
26、art of the test specimen which has uniform and minimum cross-section area 4.4 gauge length, L0initial distance between reference points on the test specimen in the calibrated length at test temperature, at the moment when loading is completed 4.5 controlled temperature zone part of the calibrated le
27、ngth including the gauge length where the temperature is within 50 C of the test temperature 4.6 initial cross section area, A0initial cross section area of the test specimen within the calibrated length, at test temperature 4.7 applied tensile force constant force applied to the test specimen durin
28、g the test 4.8 applied tensile stress applied tensile force divided by the initial cross section area 4.9 longitudinal deformation, L change in the gauge length caused by creep 4.10tensile creep strain, cr relative change in the gauge length at time t, caused by creep NOTE The value corresponding to
29、 rupture is denoted cr,m. 4.11creep rupture time, tcr,mtime elapsed from the moment when loading is completed until the moment of rupture 4.12 creep strain rate, the type of heating system; the type of gripping system. The volume in the gauge length shall be representative of the material. The total
30、 specimen length will depend on the furnace and on the loading system. NOTE Generally the total length is greater than 150 mm. EN 13235:2006 (E) 10 8 Test specimen preparation 8.1 Machining and preparation During cutting out, care shall be taken to align the test specimen axis with the desired fibre
31、 related loading axis. Machining parameters which avoid damage to the material shall be established and documented. These parameters shall be adhered to during test specimen preparation. 8.2 Number of test specimens At least five valid test results, as specified in 9.5 are required. By agreement bet
32、ween parties the number of valid test results per datum point may be reduced. 9 Test procedures 9.1 Test set-up: temperature considerations 9.1.1 General The following determinations shall be carried out under conditions representative of the tests, and shall be repeated every time there is a change
33、 in material, in specimen geometry, in gripping configuration etc. Every time a test parameter of test material is changed, time shall be allowed for temperature stabilisation. 9.1.2 Controlled temperature zone Prior to testing, the temperature gradient within the calibrated length inside the furnac
34、e shall be established over the temperature range of interest. This shall be carried out by measuring specimen temperature at a minimum of three locations, which shall be the extensometer reference points and midway between the two. To establish the length of the controlled temperature zone, it is a
35、lso necessary to measure temperature outside the gauge length. The temperature variation within the controlled temperature zone and the gauge length shall meet the requirements of 6.4 (see also 4.5), respectively. Temperatures shall be measured in accordance with 6.6. If thermocouples are used to me
36、asure the temperature at different locations on the specimen, they shall be embedded (and sealed if necessary) into the specimen to a depth approximately equal to half the specimen dimension in the direction of insertion. 9.1.3 Temperature calibration The test temperature can be determined either di
37、rectly by measurement on the specimen itself, or indirectly from the temperature indicated by the temperature control device. In the latter case, calibration is necessary. The relationship between the control temperature and test specimen temperature at the centre of the gauge length shall be establ
38、ished beforehand on a dummy test specimen over the range of temperature of interest. NOTE The relationship between the temperature indicated by the temperature control system and the test temperature is usually established simultaneously with the controlled temperature zone. EN 13235:2006 (E) 11 9.2
39、 Test set-up: loading considerations For a given test temperature, it is recommended that the loading rate is set for the highest load level. Once these conditions are established they can be used for the lower load levels. Loading shall be sufficiently fast in order to insure that creep deformation
40、 does not add to the pure tensile deformation during the loading phase. To determine the loading rate which minimises the creep phenomenon; it is necessary to carry out two tests with different loading rates, at the highest load level. If the longitudinal deformations differ by less than 10 % for th
41、e two tests, either of the two rates can be used for all tests. If the longitudinal deformations differ by more than 10 %, another test at a higher loading rate is carried out. This is repeated until deformations fall within 10 %. Two cases can be distinguished: a) when using an universal test machi
42、ne: in this case, tensile tests shall be carried out at the required load level in accordance with EN 1892; b) when using a creep testing rig: the same load shall be applied with two different time conditions. 9.3 Test set-up: measurement of test specimen dimensions The cross section area is determi
43、ned at the centre of the specimen and at each end of the gauge length. The cross section area varies with temperature and the variation is very difficult to measure, for this reason, cross section area is measured at room temperature. Dimensions shall be measured to an accuracy of 0,01 mm. The arith
44、metic means of the measurements shall be used for calculations. If the test specimen is equipped with marks, the gauge length measured at room temperature shall be known with an accuracy of 1 %. If thermal expansion between room temperature and the temperature of test is less than the tolerance on t
45、he gauge length measurement, then the gauge length can be measured at room temperature. If this is not the case, the gauge length shall be corrected to take the thermal expansion into account, or shall be measured at temperature. 9.4 Test technique 9.4.1 Specimen mounting Install the test specimen i
46、n the gripping system with its longitudinal axis coinciding with that of the test machine. Care shall be taken not to induce flexural or torsional load. In some cases, it is necessary to apply a preload during the whole heating period to prevent the alignment from being lost. The preload shall not i
47、ncrease beyond 5 % of the expected failure load at any moment. 9.4.2 Setting of extensometer In the case where a contacting extensometer is positioned at ambient temperature, the extensometer output shall be adjusted to read zero after the stabilisation period at the test temperature. EN 13235:2006
48、(E) 12 NOTE In the case where the material has a high thermal expansion coefficient, it is recommended that the extensometer is mechanically preset, taking expansion into account in order to be close to zero when at the test temperature. 9.4.3 Setting of inert atmosphere When testing under inert gas
49、, any air or water vapour shall be removed before setting the inert atmosphere. This can be carried out by establishing vacuum (below 10 Pa) in the enclosure, or by circulating inert gas. When testing under vacuum, the vacuum level shall be in accordance with the requirements of 6.3.3. 9.4.4 Heating of test specimen Heat the test specimen to the required test temperature, and maintain this temperature for a period to allow for temperature stabilisation and when applicable, for stabilisat
