1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 28704:2011Fine ceramics (advancedceramics, advanced technicalceramics) Test methodfor cyclic bending fatigueof porous ceramics at roomtemperatureBS ISO 28704:2011 BRITISH
2、STANDARDNational forewordThis British Standard is the UK implementation of ISO 28704:2011.The UK participation in its preparation was entrusted to TechnicalCommittee RPI/13, Advanced technical ceramics.A list of organizations represented on this committee can beobtained on request to its secretary.T
3、his publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2011ISBN 978 0 580 66976 7ICS 81.060.30Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published unde
4、r the authority of theStandards Policy and Strategy Committee on 30 September 2011.Amendments issued since publicationDate Text affectedBS ISO 28704:2011Fine ceramics (advanced ceramics, advanced technical ceramics) Test method for cyclic bending fatigue of porous ceramics at room temperatureCramiqu
5、es techniques Mthode dessai de fatigue par flexion cyclique des cramiques poreuses temprature ambiante ISO 2011Reference numberISO 28704:2011(E)First edition2011-08-15ISO28704INTERNATIONAL STANDARDBS ISO 28704:2011ISO 28704:2011(E)COPYRIGHT PROTECTED DOCUMENT ISO 2011All rights reserved. Unless othe
6、rwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright
7、 officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in Switzerlandii ISO 2011 All rights reservedBS ISO 28704:2011ISO 28704:2011(E)Contents PageForeword iv1 Scope 12 Normative references .13 Terms and definitions .14 Test
8、ing machine and equipment .34.1 Testing machine .34.2 Loading precision .34.3 Test fixture .44.4 Micrometer callipers for measurement of external dimensions .44.5 Dial gauge 44.6 Vernier callipers .45 Test piece .55.1 Test piece size 55.2 Test piece preparation 56 Test method 56.1 Waveform of loadin
9、g stress 56.2 Loading method .56.3 Number of cycles for interruption .66.4 Reuse of test piece .66.5 Recommended test procedure in fatigue test .66.6 Test environment .67 Treatment of test result 67.1 Maximum stress .67.2 Number of cycles to failure .77.3 S-N plot .78 Test report .7 ISO 2011 All rig
10、hts reserved iiiBS ISO 28704:2011ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body inter
11、ested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
12、 Commission (IEC) on all matters of electrotechnical standardization.International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the tech
13、nical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO s
14、hall not be held responsible for identifying any or all such patent rights.ISO 28704 was prepared by Technical Committee ISO/TC 206, Fine ceramics.ISO 28704:2011(E)iv ISO 2011 All rights reservedBS ISO 28704:2011INTERNATIONAL STANDARD ISO 28704:2011(E)Fine ceramics (advanced ceramics, advanced techn
15、ical ceramics) Test method for cyclic bending fatigue of porous ceramics at room temperature1 ScopeThis International Standard spedifies a test method for determining the cyclic four-point bending fatigue of porous ceramics in air at room temperature.2 Normative referencesThe following referenced do
16、cuments 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.ISO 463, Geometrical Product Specifications (GPS) Dimensional measuring equip
17、ment Design and metrological characteristics of mechanical dial gaugesISO 1101, Geometrical Product Specifications (GPS) Geometrical tolerancing Tolerancing of form, orientation, location and run-outISO 3611, Geometrical product specifications (GPS) Dimensional measuring equipment: Micrometers for e
18、xternal measurements Design and metrological characteristicsISO 3599, Vernier callipers reading to 0,1 and 0,05 mmISO 4287, Geometrical Product Specifications (GPS) Surface texture: Profile method Terms, definitions and surface texture parametersISO 14704, Fine ceramics (advanced ceramics, advanced
19、technical ceramics) Test method for flexural strength of monolithic ceramics at room temperatureISO 20507, Fine ceramics (advanced ceramics, advanced technical ceramics) VocabularyISO 22214, Fine ceramics (advanced ceramics, advanced technical ceramics) Test method for cyclic bending fatigue of mono
20、lithic ceramics at room temperatureISO 80000-1, Quantities and units Part 1: General3 Terms and definitionsFor the purposes of this document, the terms and definitions in ISO 20507 and the following apply.3.1porous fine ceramicsceramics with a porosity of typically 30 % to 60 % and a pore diameter o
21、f 1 m to 100 m, for applications such as filters, catalyst carriers, humidity sensors or molecular sieves, excluding structured honeycomb cellular channels3.2fatigue testtest wherein a test piece is subjected to repeated stressing to a set stress level, and the number of cycles to fracture is determ
22、ined ISO 2011 All rights reserved 1BS ISO 28704:20113.3four-point bending stressmaximum value of stress generated in flexure in a bar-shaped test piece when supported at two support points near its ends and loaded symmetrically by two loading points between them3.4cyclic stressstress which is simply
23、 and cyclically loaded between a specific maximum value and a specific minimum value (see Figure 1)3.5maximum stresssmaxmaximum value of cyclic stress (see Figure 1)3.6minimum stresssminminimum value of cyclic stress (see Figure 1)12YXmaxminKeyX timeY stress1 smin2 smaxFigure 1 Cyclic stress3.7minim
24、um to maximum stress ratioRratio of minimum stress to maximum stressR =minmax(1)3.8number of cyclesnnumber of cycles of stress in the fatigue test3.9number of cycles to failureNnumber of cycles of stress until fatigue failure occursISO 28704:2011(E)2 ISO 2011 All rights reservedBS ISO 28704:20113.10
25、failure timeloading time until fatigue failure occurs3.11S-N plotdiagram wherein the maximum stress, S, is taken as an ordinate and the fracture number of cycles, N, is taken as an abscissaNOTE An example is given in Figure 2, where the number attached to the data point indicates the number of test
26、pieces and the data with a right-pointing arrow indicates a “run-out”.10-11001011021031041051061001011021031041051061071085040302010X1YX2222KeyX1 number of cycles to failure, NX2 time to failure (s)Y maximum stress (MPa)2 number of superimposed pointsFigure 2 Example of S-N plot4 Testing machine and
27、 equipment4.1 Testing machineA testing machine shall be so constructed that a cyclic bending stress can be applied to a test piece, and a force or moment other than the cyclic bending stress is not applied. The testing machine shall be equipped with apparatus for measuring or indicating the maximum
28、and minimum load, apparatus capable of measuring the number of cycles until the test piece is broken, and a mechanism wherein when the testing machine is stopped for reasons of power failure or others, its automatic reactivation is prevented.4.2 Loading precisionThe fluctuation of the maximum stress
29、 shall be within 1 % of the chosen value, and that of the minimum to maximum stress ratio shall be within 5 % thereof, as specified in ISO 22214.ISO 28704:2011(E) ISO 2011 All rights reserved 3BS ISO 28704:20114.3 Test fixtureA four-point flexure fixture of the type and function shown in ISO 14704 s
30、hall be used (see Figure 3). The use of a semi- or fully-articulating fixture is required to prevent torsional deformation. Bearings supporting the test piece at the support points and loading the test piece at the loading points shall be of equal shape and have a length exceeding the width of the t
31、est piece. The material of the bearings shall have an elastic modulus of at least 140 GPa, and shall be free from plastic deformation; the bearing shall never break during the test. The radius of curvature at the tip of the bearings shall be 2,0 mm to 3,0 mm, and their surface roughness, Ra, as spec
32、ified in ISO 4287, shall be not greater than 0,40 m.The test piece and/or its bearings may move during the test. Precautions should be taken where possible to minimise such movement without restricting the flexural displacement, for example, by providing support rollers with restraint against a stop
33、 in the correct position.l/2L/2 L/2l/2b2D3d1Key1 test piece2 external support3 internal supportD roller diameter (4 to 6 mm)L outer span (L = 60 mm 0,5 mm)l inner span (l = 30 mm 0,5 mm)Figure 3 Four-point flexure fixture4.4 Micrometer callipers for measurement of external dimensionsMicrometer calli
34、pers for the measurement of external dimensions with the same accuracy of 0,01 mm as specified in ISO 3611, or better, shall be used.4.5 Dial gaugeDial gauges with the same accuracy of minimum reading of 0,01 mm as specified in ISO 463, or better, shall be used.4.6 Vernier callipersVernier callipers
35、 with the same accuracy of minimum reading of 0,05 mm as specified in ISO 3599, or better, shall be used.ISO 28704:2011(E)4 ISO 2011 All rights reservedBS ISO 28704:20115 Test piece5.1 Test piece sizeThe shape of a test piece shall be a beam of uniform rectangular cross-section. Its standard dimensi
36、ons shall be 70 mm 0,5 mm in total length, 8,0 mm 0,1 mm in width, and 6,0 mm 0,1 mm in thickness. The parallelism between the upper and lower surfaces of the test piece shall be better than 0,02 mm, as specified in ISO 1101. The longer edges shall be rounded or chamfered by an amount of 0,1 mm to 0
37、,3 mm, as given in Figure 4. This chamfering shall be carried out with caution so as not to introduce defects resulting in a fracture initiation site. The chamfering is not necessary when the grain size of material is larger than 0,1 mm. Before carrying out the test, the width and thickness of the t
38、est piece shall be measured to the nearest 0,1 mm by using micrometer callipers (4.4).If, for any reason, different test piece dimensions have to be used, they shall be stated in the test report.LTbcd45KeyLTlength of test piece (LT= 70 mm 0,5 mm)b width of test piece (b = 8,0 mm 0,1 mm)d thickness o
39、f test piece (d = 6,0 mm 0,1 mm)c chamfer or rounding (c = 0,1 mm to 0,3 mm)Figure 4 Test piece dimensions and chamfering of ridge line5.2 Test piece preparationThe surface shall be finished by grinding with a wheel of grain size 20 m or smaller. The contamination by wax, if any, should be removed b
40、y organic solution or by heating at 773 K (500 C) for 1 h to evaporate wax.6 Test method6.1 Waveform of loading stressThe waveform shall be sinusoidal and the ratio of minimum to maximum stress R = 0,1. The frequency shall be selected by agreement between parties, with 20 Hz being recommended. For o
41、ther cases, the waveform of the loading stress shall be stated in the test report. A series of tests shall be carried out using the same stress waveform.6.2 Loading method6.2.1 The distances between internal support points and external support points shall be measured by a calliper before the tests.
42、6.2.2 The test piece shall be centrally positioned in the test fixture.6.2.3 The number of cycles from the start of loading to the end of adjusting to a specific cyclic loading stress shall be as few as possible. In this case, the stress during initial adjusting shall not exceed the specific maximum
43、 stress.ISO 28704:2011(E) ISO 2011 All rights reserved 5BS ISO 28704:20116.2.4 The test shall, as a rule, be carried out without a pause on the same test piece from start to end. However, when the test is interrupted for any reason, the number of cycles to the interruption and the duration of interr
44、uption shall be recorded.6.2.5 The fatigue test shall be carried out on at least three test pieces at each of at least three maximum stress levels.6.3 Number of cycles for interruptionUnless otherwise specified, if the test piece is not fractured by 107loading cycles, the test may be halted, and the
45、 result deemed to be a “run-out” and indicated on the plot of results with a right-pointing arrow.6.4 Reuse of test pieceDo not reuse a test piece which has been used once.6.5 Recommended test procedure in fatigue testWhen the maximum stress and the number of test pieces in a fatigue test are not pr
46、eviously agreed upon between the purchaser and the supplier, the test may be carried out according to the following procedure.6.5.1 Measurement of flexural strengthIn order to obtain the standard value of the maximum stress in a fatigue test, measure the flexural strength of a test piece prior to th
47、e fatigue test. Use the test piece of the same shape as that of a fatigue test piece for measurement of flexural strength, and obtain it by the same loading method as that of the fatigue test. Allow the speed of a cross-head in the measurement of flexural strength to be 0,5 mm/min. Calculate the fle
48、xural strength from the measured maximum forces of respective test pieces.6.5.2 Stress level in fatigue testDetermine the maximum stress in a fatigue test by referring to the arithmetic mean value of the flexural strength obtained by the measurement in 6.5.1. Start the fatigue test from a condition
49、wherein the maximum stress is high, and preferably measure the life of at least three test pieces by the same stress. When all the test pieces tested at the same stress are unfailed at the selected number of cycles for test termination, select a higher stress level for the next group of test pieces. Do not carry out tests at a lower stress level. It is preferred that the results of a test programme should contain at least three valid failures at each of at least three maximum stress
