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1、DRAFT FOR DEVELOPMENT DD CEN/TS 14425-5:2004 Advanced technical ceramics Test methods for determination of fracture toughness of monolithic ceramics Part 5: Single-edge vee-notch beam (SEVNB) method ICS 81.060.30 ? Licensed Copy: London South Bank University, London South Bank University, Tue Dec 12
2、 06:03:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI DD CEN/TS 14425-5:2004 This Draft for Development was published under the authority of the Standards Policy and Strategy Committee on 21 February 2005 BSI 21 February 2005 ISBN 0 580 45492 4 National foreword This Draft for Development is the offi
3、cial English language version of CEN/TS 14425-5:2004. This publication is not to be regarded as a British Standard. It is being issued in the Draft for Development series of publications and is of a provisional nature because it is considered that further experience is required in its application be
4、fore it is converted to a European and hence British Standard. It should be applied on this provisional basis, so that information and experience of its practical application may be obtained. Comments arising from the use of this Draft for Development are requested so that UK experience can be repor
5、ted to the European organization responsible for its conversion to a European Standard. A review of this publication will be initiated 2 years after its publication by the European organization so that a decision can be taken on its status at the end of its 3-year life. Notification of the start of
6、the review period will be made in an announcement in the appropriate issue of Update Standards. According to the replies received by the end of the review period, the responsible BSI Committee will decide whether to support the conversion into a European Standard, to extend the life of the Technical
7、 Specification or to withdraw it. Comments should be sent in writing to the Secretary of BSI Technical Committee RPI/13, Advanced technical ceramics, at British Standards House, 389 Chiswick High Road, London W4 4AL, giving the document reference and clause number and proposing, where possible, an a
8、ppropriate revision of the text. 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 this document may be found in the BSI Catalogue under the s
9、ection entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. Summary of pages This document comprises a front cover, an inside front cover, the CEN/TS title page, pages 2 to 19 and a back cover. The
10、BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: London South Bank University, London South Bank University, Tue Dec 12 06:03:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI TECHNICAL S
11、PECIFICATION SPCIFICATION TECHNIQUE TECHNISCHE SPEZIFIKATION CEN/TS 14425-5 August 2004 ICS 81.060.30 English version Advanced technical ceramics - Test methods for determination of fracture toughness of monolitic ceramics - Part 5: Single-edge vee-notch beam (SEVNB) method Cramiques techniques avan
12、ces - Mthodes dessai pour la dtermination de la rsistance la fracture des cramiques monolithiques - Partie 5: Mthode du faisceau entaille en V sur bord simple (SEVNB) Hochleistungskeramik - Prfverfahren zur Bestimmung der Bruchzhigkeit von monolithischer Keramik - Teil 5: Verfahren fr Biegeproben mi
13、t V-Kerb (SEVNB-Verfahren) This Technical Specification (CEN/TS) was approved by CEN on 4 April 2004 for provisional application. The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit their comments, particularly on
14、the question whether the CEN/TS can be converted into a European Standard. CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS available promptly at national level in an appropriate form. It is permissible to keep conflicting national
15、 standards in force (in parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached. CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
16、 Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: rue de Stassart, 36
17、 B-1050 Brussels 2004 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. CEN/TS 14425-5:2004: E Licensed Copy: London South Bank University, London South Bank University, Tue Dec 12 06:03:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI CEN
18、/TS 14425-5:2004 (E) 2 Contents Page Foreword. 3 1 Scope 4 2 Normative references . 4 3 Terms and definitions. 4 4 Principle. 4 5 Apparatus 5 5.1 Razor blades 5 5.2 Diamond paste 5 5.3 Lubricant 5 5.4 Test piece support 5 5.5 Flexural strength test jig 5 5.6 Mechanical testing machine 6 5.7 Ultrason
19、ic cleaning bath 6 5.8 Micrometer. 6 5.9 Microscope 6 5.10 Notch measuring device. 6 5.11 Drying oven . 6 5.12 Diamond slitting saw 6 6 Test piece preparation 7 6.1 Number of test pieces. 7 6.2 Test-piece dimensions . 7 6.3 Preparing the V-notch by hand 7 6.4 Preparing the V-notches by machine (opti
20、onal) 10 7 Test procedure 10 7.1 Determination of notch root radius. 10 7.2 Dimensions of test-piece 11 7.3 Flexural strength test 11 7.4 Measurement of notch depth. 12 7.5 Calculation of fracture toughness. 13 8 Precision and bias 14 9 Test report . 14 Annex A (informative) Notch honing by machine
21、. 16 Annex B (informative) Interlaboratory evaluation of the SEVNB fracture toughness test procedures. 17 Bibliography . 19 Licensed Copy: London South Bank University, London South Bank University, Tue Dec 12 06:03:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI CEN/TS 14425-5:2004 (E) 3 Foreword Thi
22、s document (CEN/TS 14425-5:2004) has been prepared by Technical Committee CEN/TC 184 “Advanced technical ceramics”, the secretariat of which is held by BSI. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to announce this T
23、echnical Specification: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.
24、CEN/TS 14425 Advanced technical ceramics Test methods for determination of fracture toughness of monolithic ceramics consists of five parts: Part 1: Guide to test method selection Part 2: Single-edge pre-cracked beam (SEPB) method Part 3: Chevron notched beam (CNB) (method Part 4: Surface crack in f
25、lexure (SCF) method Part 5: Single-edge V-notch beam (SEVNB) method Licensed Copy: London South Bank University, London South Bank University, Tue Dec 12 06:03:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI CEN/TS 14425-5:2004 (E) 4 1 Scope This part of CEN/TS 14425 describes a method for the determi
26、nation of the fracture toughness of advanced technical ceramics. The procedure makes use of V-notched bars, which are loaded in 4- point bending until failure. It is applicable to ceramics with a grain size or major microstructural feature size larger than about 1 m. 2 Normative references The follo
27、wing 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 843-1, Advanced technical ceramics Monolithic ceramics
28、Mechanical properties at room temperature Part 1: Determination of flexural strength ENV 1006, Advanced technical ceramics Monolithic ceramics Guidance on the selection of test pieces for the evaluation of properties CEN/TS 14425-1, Advanced technical ceramics Test methods for determination of fract
29、ure toughness of monolithic ceramics - Part 1: Guide to test method selection EN ISO 7500-1, Metallic materials - Verification of static uniaxial testing machines - Part 1: Tension/compression testing machines (ISO 7500-1:1999) EN ISO/IEC 17025, General requirements for the competence of testing and
30、 calibration laboratories (ISO/IEC 17025:1999) ISO 3611, Micrometer callipers for external measurement 3 Terms and definitions For the purposes of this document, the terms and definitions given in CEN/TS 14425-1 apply. 4 Principle This method of conducting a fracture toughness test is based on the p
31、reparation and fracture of bar test pieces in which a sharp-tipped notch is machined. Using the technique of a reciprocating razor blade and diamond paste, a narrow notch can be honed into a test piece using either a manual method or a simple machine. Under well-controlled conditions a notch tip rad
32、ius in the range of 1 m to 20 m can be prepared depending on the grain size of the test material. For many materials this is a close approximation to a sharp crack, and the method has been found to give fracture toughness values very close to those of other methods such as the single-edge pre-cracke
33、d beam (SEPB) method (prCEN/TS 14425-2) or the surface crack in flexure (SCF) method (prCEN/TS 14425-4). The method has advantages of simplicity of notch production compared with using a sharp-tipped diamond saw or a diamond impregnated wire in which the tip radius is normally greater than 50 m. The
34、 method is often easier to undertake compared with other methods of pre-cracking, and is applicable to a wider range of materials outside the scope of these other methods. Licensed Copy: London South Bank University, London South Bank University, Tue Dec 12 06:03:57 GMT+00:00 2006, Uncontrolled Copy
35、, (c) BSI CEN/TS 14425-5:2004 (E) 5 The method has been extensively researched (see Bibliography) and has been evaluated in ESIS1 )/VAMAS2 ) round robin testing, the results of which are summarised in Annex B. This recommended practice is based upon the ESIS/VAMAS single edge V-notch beam (SEVNB) ro
36、und robin testing. The method may have some limitations for materials with grain sizes of less than 1 m, for which the assumption that the notch approximates to a sharp crack may not be valid. 5 Apparatus 5.1 Razor blades Standard razor blades, preferably with a support along one edge but alternativ
37、ely inserted into a suitable holder. NOTE 1 Razor blades thinner than about 0,2 mm may not be stiff enough by themselves for this task. If the razor blades are not stiff enough, it is recommended to glue or screw the blades between two steel plates leaving only about 2 mm of edge showing. It is reco
38、mmended to use a razor blade with a tip angle of 30, or smaller. NOTE 2 Although it is possible to machine the notches entirely by hand, the use of a simple device in which the test pieces are mounted and in which a razor blade primed with diamond paste is moved in a reciprocating motion across the
39、mounted test-pieces has a distinct advantage as this provides controlled loading and directional stability to the razor blade, and sharper notches can generally be produced. An example is shown in Annex A. 5.2 Diamond paste Metallographic diamond paste in a viscous organic carrier and of fine grain
40、size, typically 1 m to 3 m. 5.3 Lubricant Suitable lubricating oil for lubricating the razor blade. 5.4 Test piece support A flat plate or other suitable device for mounting test pieces during notch honing. 5.5 Flexural strength test jig A three-point or, preferably, four-point flexural strength tes
41、t jig operating in accordance with the requirements of EN 843-1. The test piece is supported on two bearing edges perpendicular to its length. The outer support bearing edges shall be parallel rollers of diameter 5,0 mm 0,2 mm and shall be capable of rolling outward on flat support surfaces. One of
42、the rollers shall additionally be capable of rotating about an axis parallel to the length of the test piece such that torsional loading is minimised. The two rollers shall be positioned initially with their centres 40,0 mm 0,5 mm apart with their axes parallel to within 1. The separation of the cen
43、tres of the rollers in their starting positions shall be measured to the nearest 0,1 mm with a travelling microscope. The rollers shall be made from hardened steel or other hard material with a hardness greater than 40 HRC (Rockwell C-scale). The 1) ESIS = European Structural Integrity Society 2) VA
44、MAS = Versailles Project on Advanced Materials and Standards Licensed Copy: London South Bank University, London South Bank University, Tue Dec 12 06:03:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI CEN/TS 14425-5:2004 (E) 6 rollers shall have a smooth burr-free surface finish with roughness less th
45、an 0,5 m Ra, and shall have a diameter uniform to 0,02 mm. For four-point flexure, the two loading rollers are located at the quarter points, with an inner span of 20 mm 0,2 mm and are free to roll inwards. The rollers are free to rotate separately about an axis parallel to the length of the test pi
46、ece to allow alignment. For three-point flexure, the single loading roller, which need not rotate, shall be positioned centrally between the outer support rollers. The distances between the rollers shall be measured to the nearest 0,1 mm along the length of the specimen perpendicular to the directio
47、n of loading, using a travelling microscope or other suitable device. The loading rollers in four-point flexure shall be symmetrically positioned to within 0,1 mm. The single loading roller in three-point flexure shall be centrally located to within 0,2 mm. The arrangement for loading shall ensure t
48、hat equal forces are applied to the two loading rollers. 5.6 Mechanical testing machine Mechanical testing machine capable of applying a force at a constant rate of displacement or constant loading rate to the test piece in the flexural strength test jig and of recording the force at which the test
49、piece fractures. The force measuring device shall be in accordance with EN ISO 7500-1 and shall be accurate to better than 1 %. 5.7 Ultrasonic cleaning bath For cleaning the test pieces after notching, an ultrasonic bath suitable for insertion of a beaker or other receptacle containing solvent. 5.8 Micrometer A calibrated micrometer similar to one in accordance with ISO 3611, but capable of being read to a precision of 0,002 mm using a vernier or electronic r