1、BRITISH STANDARDBS EN 843-1:2006Advanced technical ceramics Mechanical properties of monolithic ceramics at room temperature Part 1: Determination of flexural strengthThe European Standard EN 843-1:2006 has the status of a British StandardICS 81.060.30g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g5
2、6g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 843-1:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 January 2007 BSI 2007IS
3、BN 978 0 580 49980 7National forewordThis British Standard was published by BSI. It is the UK implementation of EN 843-1:2006. It supersedes BS EN 843-1:1995 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee RPI/13, Advanced technical ceramics.A list of
4、organizations represented on RPI/13 can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.
5、 Amendments issued since publicationAmd. No. Date CommentsEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 843-1December 2006ICS 81.060.30 Supersedes EN 843-1:1995 English VersionAdvanced technical ceramics - Mechanical properties ofmonolithic ceramics at room temperature - Part 1: Determinationof
6、flexural strengthCramiques techniques avances - Proprits mcaniquesdes cramiques monolithiques temprature ambiante -Partie 1: Dtermination de la rsistance en flexionHochleistungskeramik - Mechanische Eigenschaftenmonolithischer Keramik bei Raumtemperatur - Teil 1:Bestimmung der BiegefestigkeitThis Eu
7、ropean Standard was approved by CEN on 11 November 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 alteration. Up-to-date lists and bibliographical references
8、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 translationunder the responsibility of a CEN member into its ow
9、n 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, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg
10、, 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 de Stassart, 36 B-1050 Brussels 2006 CEN All rights of ex
11、ploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 843-1:2006: EEN 843-1:2006 (E) 2 Contents Page Foreword3 1 Scope 4 2 Normative references 4 3 Terms and definitions .5 4 Significance and use .5 5 Apparatus .6 5.1 Test jig 6 5.2 Test machine8 5.3 Micromet
12、er or alternative calibrated device .8 5.4 Travelling microscope.8 5.5 Humidity measuring device 9 6 Test pieces .9 6.1 General9 6.2 Dimensions and tolerances 9 6.3 Surface finish .10 6.4 Number of test pieces .13 6.5 Precautions 13 7 Procedure .13 8 Calculations14 9 Test report 15 Annex A (informat
13、ive) Typical fracture patterns in ceramic test pieces .17 Bibliography 20 EN 843-1:2006 (E) 3 Foreword This document (EN 843-1:2006) has been prepared by Technical Committee CEN/TC 184 “Advanced technical ceramics”, the secretariat of which is held by BSI. This European Standard shall be given the s
14、tatus of a national standard, either by publication of an identical text or by endorsement, at the latest by June 2007, and conflicting national standards shall be withdrawn at the latest by June 2007. This document supersedes EN 843-1:1995. EN 843 Advanced technical ceramics Mechanical properties o
15、f monolithic ceramics at room temperature comprises six parts: Part 1: Determination of flexural strength Part 2: Determination of Youngs modulus, shear modulus and Poissons ratio Part 3: Determination of subcritical crack growth parameters from constant stressing rate flexural strength tests Part 4
16、: Vickers, Knoop and Rockwell superficial hardness Part 5: Statistical analysis Part 6: Guidance for fractographic investigation At the time of publication of this Revision of Part 1, Part 6 was available as a Technical Specification. According to the CEN/CENELEC Internal Regulations, the national s
17、tandards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal
18、, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 843-1:2006 (E) 4 1 Scope This part of EN 843 specifies methods for determining the nominal flexural strength of advanced monolithic technical ceramic materials at ambient temperature. The available loading geometries ar
19、e three- and four-point flexure, using rectangular section test pieces of two prescribed geometries: 20 mm support span (A) and 40 mm support span (B). NOTE This part of EN 843 differs from ISO 14704 (see Bibliography) in respect of span A (not included in the ISO version), the absence of the 30 mm
20、span option, and the required use of a fully articulating test jig. The test applies to materials with grain size less than 200 m. The test prescribes four categories of surface finish applied to the test pieces: I: as-fired or annealed after machining; II: standard finishing by grinding; III: stand
21、ard finishing by lapping/polishing; IV: machined using agreed grinding procedures and material removal rates. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references
22、, the latest edition of the referenced document (including any amendments) applies. EN 623-4, Advanced technical ceramics Monolithic ceramics General and textural properties Part 4: Determination of surface roughness EN 843-5, Advanced technical ceramics Mechanical properties of monolithic ceramics
23、at room temperature Part 5: Statistical analysis EN ISO 7500-1, Metallic materials Verification of static uniaxial testing machines Part 1: Tension/compression testing machines Verification and calibration of the force-measuring system (ISO 7500-1:2004) EN ISO/IEC 17025, General requirements for the
24、 competence of testing and calibration laboratories (ISO/IEC 17025:2005) ISO 3611, Micrometer callipers for external measurement ISO 4677-1, Atmospheres for conditioning and testing Determination of relative humidity Part 1: Aspirated psychrometer method ISO 4677-2, Atmospheres for conditioning and
25、testing Determination of relative humidity Part 2: Whirling psychrometer method EN 843-1:2006 (E) 5 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 nominal flexural strength maximum nominal stress supported by the material at the instant of f
26、ailure when loaded in linear elastic bending 3.2 three-point flexure means of bending a beam test piece whereby the test piece is supported on bearings near its ends and a central force is applied 3.3 four-point flexure means of bending a beam test piece whereby the test piece is supported on bearin
27、gs near its ends and is loaded equally at two positions symmetrically disposed about the centre of the supported span 3.4 quarter-point flexure four-point flexure (3.3) wherein the loading bearings are each one-quarter of the support span from the support bearings 4 Significance and use This test is
28、 intended to be used for material development, quality control, characterization and design data acquisition purposes. The strength level determined by the test is calculated on the basis of linear elastic bending of a thin beam on the assumption that the material being tested is elastically homogen
29、eous and isotropic, and shows linear (Hookean) stress-strain behaviour. The result obtained from a strength test is determined by a large number of factors associated with the microstructure of the material, the surface finishing procedure applied in preparation of the test pieces, the size and shap
30、e of the test piece, the mechanical function of the testing apparatus, the rate of load application and the relative humidity of the ambient atmosphere. As a consequence of the brittle nature of ceramics, there is usually a considerable range of results obtained from a number of nominally identical
31、test pieces. These factors combined mean that caution in the interpretation of test results is required. For many purposes, and as described in this European Standard, the results of strength tests may be described in terms of a mean value and a standard deviation. Further statistical evaluation of
32、results is required for design data acquisition, and may be desirable for other purposes (see EN 843-5). This method places closely defined restrictions on the size and shape of the test piece and on the function of the test apparatus in order to minimize the errors that can arise as a consequence o
33、f the test method. NOTE The basis for the choice of dimensions and tolerances of test pieces and of the requirements of the test-jig may be found in reference 4. All other test factors are required to be stated in the test report (see Clause 9) in order to allow inter-comparison of material behaviou
34、rs. It is not possible to rigorously standardize particular surface finishes, since these are not absolutely controllable in mechanical terms. The inclusion of a standard grinding procedure (see 6.3) as one of the surface finish options in this method is intended to provide a means of obtaining a mi
35、nimum amount of residual grinding damage in the test material. The extrapolation of flexural strength data to other geometries of stressing, to multiaxial stressing, to other rates of stressing or to other environments should be viewed with caution. EN 843-1:2006 (E) 6 The origin of fracture in a fl
36、exural test can be a valuable guide to the nature and position of strength-limiting defects. Fractography of test pieces is highly recommended. In particular, the test may identify fracture origins as being edge defects (caused by edge preparation), surface defects (caused by surface preparation), o
37、r internal defects (caused by manufacturing inhomogeneities such as pores, large grains, impurity concentrations etc.). Not all advanced monolithic technical ceramics are amenable to clear fractography. 5 Apparatus 5.1 Test jig The test jig shall be capable of either three-point or four-point flexur
38、e and functioning as specified below in order to minimize misalignments, twist and frictional forces applied to the test piece. NOTE 1 The precise test jig design is not specified, only the function. Schematic arrangements of the test jig function are shown in Figure 1 a) for three-point flexure, an
39、d Figure 1 b) for four-point flexure. The test piece shall be supported on two bearing edges perpendicular to its length. The outer support bearing edges shall be parallel rollers of diameter approximately 1,5 times the test piece thickness. Diameters of between 2,2 mm and 2,5 mm (for span A - see 6
40、.2) or between 4,5 mm and 5,0 mm (for span B - see 6.2) are recommended. The rollers shall be capable of rolling outward on flat support surfaces. One of the rollers shall additionally be capable of rotating about an axis parallel to the length of the test piece such that torsional loading is minimi
41、zed. The two rollers shall be positioned initially with their centres 20 mm 0,5 mm apart (span A) or 40 mm 0,5 mm apart (span B) with their axes parallel to 0,2 mm over their lengths ( 12 mm). See Figure 2. For three-point flexure, a third roller shall be located at the mid-point between and paralle
42、l to the two support rollers (Figures 2 a) and 2 c). This roller shall have the same diameter as the support rollers and shall be similarly free to rotate about an axis parallel to the length of the test piece. Its position relative to the midpoint between the support rollers shall be better than 0,
43、2 mm, measured to the nearest 0,1 mm in a direction parallel to the length of the test piece using the travelling microscope or other suitable device (see 5.4). For four-point flexure, two loading rollers shall be located at the quarter points (see 3.4), i.e. with inner spans 10 mm 0,2 mm (outer spa
44、n A) or 20 mm 0,2 mm (outer span B), and shall be free to roll inwards (Figures 2 b) and 2 d). As with the three-point apparatus, the two rollers shall also be free to rotate separately about an axis parallel to the length of the test piece to allow alignment. The loading rollers shall be symmetrica
45、lly positioned to within 0,1 mm. The distances between the centres of the support rollers and adjacent loading rollers shall be measured to the nearest 0,1 mm along the length of the test piece perpendicular to the direction of loading, using the travelling microscope or other suitable device (see 5
46、.4). The arrangement for loading shall ensure that equal forces are applied to the two loading rollers. The separation of the centres of the rollers in their starting positions shall be measured to the nearest 0,1 mm with the travelling microscope (see 5.3.2) or other suitable device. The rollers sh
47、all be made from hardened steel or other hard material with a hardness greater than 40 HRC (Rockwell C-scale) for strengths less than 1,4 GPa and not less than 46 HRC for strengths greater than 1,4 GPa. The rollers shall have a smooth burr-free surface finish with roughness less than 0,5 m Raand sha
48、ll have diameter uniform to 0,015 mm. NOTE 2 The accurate and repeatable lateral positioning of the rollers can best be achieved by ensuring that in the unloaded position, the support rollers are in lateral contact with stops which allow them to roll outwards on their support planes towards the ends
49、 of the test piece, and the inner loading rollers (four-point flexure) are in contact with stops which allow rolling inwards towards the middle of the test piece. The rotation of the rollers is thus unhindered when the test force is applied. EN 843-1:2006 (E) 7 FF/2F/2213a) three-point bend jig 4F/2F/21F/2F/23b) four-point bend jig Key 1 rolling but non-articulating support roller 2 articulating loading roller 3 rolling and articulating support roller 4 rolling and articulating loading roller Figure 1 Schematic diag
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