【BS英國標準】BS EN 820-3-1995 Advanced technical ceramics — Methods of testing monolithic ceramics — Thermomechanical properties.doc

-,-,-british standard bs en820-3:2004advanced technical ceramics methods of testing monolithic ceramics thermomechanical properties part 3: determination of resistance to thermal shock by water quenchingthe european standard en 820-3:2004 has the status of abritish standardics 81.060.30 copyright british standards institutionreproduced by ihs under license with bsi - uncontrolled copydocument provided by ihs licensee=bureau veritas/5959906001, 11/08/200406:06:05 mst questions or comments about this message: please call the documentpolicy group at 303-397-2295.bs en 820-3:2004national forewordthis british standard is the official english language version ofen 820-3:2004. it supersedes dd env 820-3:1994 which is withdrawn.the uk participation in its preparation was entrusted to technical committeerpi/13, advanced technical ceramics, which has the responsibility to:aid enquirers to understand the text;present to the responsible international/european committee any enquiries on the interpretation, or proposals for change, and keep the uk interests informed;monitor related international and european developments and promulgate them in the uk.a list of organizations represented on this committee can be obtained on request to its secretary.cross-referencesthe british standards which implement international or european publications referred to in this document may be found in the bsi catalogue under the section entitled “international standards correspondence index”, or by using the “search” facility of the bsi electronic catalogue or of british standards online.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 does not of itself confer immunity from legal obligations.this british standard was published under the authority of the standards policy and strategy committee on3 september 2004 bsi 3 september 2004isbn 0 580 44412 0summary of pagesthis document comprises a front cover, an inside front cover, the en title page, pages 2 to 12, an inside back cover and a back cover.the bsi copyright notice displayed in this document indicates when the document was last issued.amd. no.datecommentsamendments issued since publication-,-,-european standard norme europenneeuropische normen 820-3august 2004ics 81.060.30supersedes env 820-3:1993english versionadvanced technical ceramics - methods of testing monolithic ceramics - thermomechanical properties - part 3: determination of resistance to thermal shock by water quenchingcramiques techniques avances - cramiques monolithiques - proprits thermomcaniques - partie 3: dtermination de la rsistance au choc thermique par la mthode de trempe leauhochleistungskeramik - prfverfahren fr monolithische keramik - thermomechanische eigenschaften - teil 3: bestimmung der thermoschockbestndigkeit mit dem wasserabschreckversuchthis european standard was approved by cen on 24 june 2004.cen members are bound to comply with the cen/cenelec internal regulations which stipulate the conditions for giving this european standard the status of a national standard without any alteration. up-to-date lists and bibliographical references concerning such national standards 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 translation under the responsibility of a cen member into its own language and notified to the central secretariat has the same status as the official versions.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, malta, netherlands, norway, poland, portugal, slovakia, slovenia, spain, sweden, switzerland and united kingdom.european committee for standardization c o m i t eur o p en de nor m a l i s a ti on eur o p i s c h es kom i tee f r nor m ung management centre: rue de stassart, 36 b-1050 brussels 2004 cenall rights of exploitation in any form and by any means reserved worldwide for cen national members.ref. no. en 820-3:2004: e-,-,-en 820-3:2004 (e)contentspageforeword .31scope.42normative references .43principle .44apparatus .55test pieces.56procedure .67test report .7annex a (informative) introduction to thermal shock behaviour .9bibliography .12-,-,-2en 820-3:2004 (e)forewordthis document (en 820-3:2004) 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 status of a national standard, either by publication of an identical text or by endorsement, at the latest by february 2005, and conflicting national standards shall be withdrawn at the latest by february 2005.this document supersedes env 820-3:1993.this document has been prepared under a mandate given to cen by the european commission and the european free trade association.en 820 advanced technical ceramics methods of testing monolithic ceramics thermomechanical properties consists of five parts: part 1:determination of flexural strength at elevated temperatures part 2:determination of self-loaded deformation part 3:determination of resistance to thermal shock by water quenching part 4:determination of flexural creep deformation at elevated temperatures part 5:determination of elastic moduli at elevated temperaturespart 4 is a european prestandard (env) and part 5 is a technical specification (cen/ts).-,-,-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, iceland, ireland, italy, latvia, lithuania, luxembourg, malta, netherlands, norway, poland, portugal, slovakia, slovenia, spain, sweden, switzerland and united kingdom.3-,-,-en 820-3:2004 (e)1scopethis part of en 820 specifies the principles of thermal shock testing, and provides a general method for conducting thermal shock tests by quenching into water for both test pieces and components by quenching into water.notethis document does not cover thermal stress developed as a result of steady inhomogeneous temperature within a ceramic body or of thermal expansion mismatch between joined bodies.2normative referencesthe 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 623-1, advanced technical ceramics monolithic ceramics general and textural properties part 1: determination of the presence of defects by dye penetration testsen 843-1, advanced technical ceramics monolithic ceramics mechanical properties at room temperatures part 1: determination of flexural strengthen 60584-1, thermocouples part 1: reference tables (iec 60584-1:1995)en 60584-2, thermocouples part 2: tolerances (iec 60584-2:1982)en 60672-2, ceramic and glass insulating materials part 2: methods of test (iec 60672-2:1999)en iso/iec 17025, general requirements for the competence of testing and calibration laboratories(iso/iec 17025:1999)3principlea set of test pieces is heated to a given temperature, and then quickly and smoothly transferred to a water bath. the test pieces or components are then inspected for cracks or other damage, either by an appropriate mechanical test to establish whether weakening has occurred, or by using a dye penetrant to detect the presence of cracks (see en 623-1).note 1dye penetration tests are unsatisfactory for porous or highly microcracked materials.this thermal shock test determines whether a material or component has a capability of withstanding a water quench through a large temperature difference from high temperature without failure, under the conditions of heat transfer prevailing in such a quenching environment, and for the given geometry and section thickness.note 2by agreement between parties an alternative quenching medium may be employed. details of the medium employed should be incorporated in the report.if the test pieces for the quench test are available as regular bar shapes, then the inspection after quenching with the mechanical test, such as a flexural test, may be preferred, as it enables the onset of loss of strength with increasing initial temperature to be determined. sets of at least five test pieces are heated to a series of temperatures above that of the quenching bath, quenched, dried and subjected to a short-term strength test. the temperature drop corresponding to that at which a sudden loss of strength occurs is termed the critical temperature difference, tc. this temperature difference can be estimated using the first kind of thermal shock parameter, r (see a.3.2), to which it is numerically equal at an infinite rate of heat transfer.4-,-,-en 820-3:2004 (e)it should be noted that although the flexural strength test method for monolithic ceramics given in en 843-1 may be employed for testing resistance to thermal shock, because of the small size of the specified test piece an overestimate of the material capability in larger sizes would occur. larger rod or bar-shaped test pieces specially prepared for the test should be employed if the behaviour of larger sections of material or components is to be assessed, e.g. type a test pieces as described in en 60672-2. as a general rule, thermal shock test results are more or less independent of test piece diameter when this exceeds about 10 mm.4apparatusthe apparatus shall consist of:a) temperature-controlled oven capable of maintaining a set of test pieces at a given temperature 5 c;b) suitable test piece holder capable of being transferred rapidly from the oven to the quenching medium within 0,5 s;c) water bath controlled at 20 c 2 c and of sufficient volume that the net temperature rise after quenching the test pieces is less than 5 c. there shall be a grid near the bottom of the water bath to prevent hot test pieces from resting directly on the bottom.the temperature of the test pieces in the oven shall be recorded by use of a suitable thermocouple manufactured in accordance with the manufacturing tolerances stated in en 60584-2, allowing the use of the reference tables in en 60584-1 or, alternatively, calibrated in a manner traceable to the international temperature scale its-90.notethe test piece holder may contain several test pieces. alternatively, test pieces may be lowered or dropped individually from the oven into the quenching medium in accordance with individual circumstances. care should be taken that no mechanical damage occurs to the test pieces as a result of transfer to the cold bath.where a flexural strength test is used, the test jig employed for rod or bar-shaped test pieces and the calculations of strength shall conform to the principles given in en 843-1.5test piecestest pieces shall either be specially prepared as rods or bars, or may be in the form of complete components where appropriate.type a:rod or bar-shaped test pieces either as-fired or with a specified surface finish in accordance with the requirements of the thermal shock test in en 60672-2.rod-shaped test pieces shall be (10 1) mm diameter, uniform to within 0,1 mm, and of length at least 120 mm.bar-shaped test pieces shall be (10 1) mm x (10 1) mm, uniform to within 0,1 mm, and of length at least 120 mm. the edges shall be chamfered.type b:bar-shaped test pieces either as-fired or with a specified surface finish in accordance with the requirements of en 843-1, size b.the dimensions shall be (3 0,2) mm x (4 0,2) mm x at least 45 mm. the edges shall be chamfered.type c:complete components in appropriate finished condition.5en 820-3:2004 (e)other sizes and shapes of test-piece are permitted subject to agreement between parties. full details of shape and dimensions shall be recorded in the report.note 1test pieces in accordance with type a will produce results which are applicable to, and give a ranking of materials performance appropriate for, larger components. test pieces in accordance with type b will require rather higher quenching temperature differences in order to induce failure. materials comparisons using this method may be valid for small components of comparable size, but it is possible that it will not correctly rank materials performance for larger or smaller cross-sections of components. test pieces in accordance with type c give results which are representative of severe quenching shock for that size, shape and manufacturing method for a specific component.note 2the ends of rod or bar test-pieces may be more prone to initiate failure than the central regions. care should be exercised over the quality of finish on the ends of bars, which should be of equivalent form and dimensions for a valid materials comparison.note 3the edges of square or rectangular bars are more prone to initiate failure than the flat or curved surfaces. chamfering of test-bar edges is critical, and the same size chamfers should be used on all bars for a valid comparison of materials.if a dye penetration method of crack detection is to be employed, at least 18 test-pieces shall be prepared, permitting three test pieces to be used at each of five test temperatures, plus three as an unshocked control. if a strength test method of damage detection is to be employed, at least 30 test-pieces shall be prepared, permitting five test pieces to be used at each of five test temperatures, plus five as an unshocked control.6procedureclean and dry the test-pieces at (120 10) c for 2 h in an oven. allow to equilibrate at room temperature before testing.if a dye penetration test is to be employed, conduct the test on three test pieces selected at random from the prepared batch in accordance with en 623-1. inspect for the presence of any damage or cracks.-,-,-notethis test is inappropriate if the material is found to be significantly porous or contains cracks in the as-received condition. thermal shock damage in such cases can be reliably assessed only through the use of strength test.if a strength test is to be employed, fracture five control test pieces selected at random from the batch, in accordance with en 60672-2 (type a test-pieces) or en 843-1 (type b test pieces) using either three or preferably four-point bending. calculate the individual and mean strengths.place three (for the dye test) or five (for the strength test) test pieces or components in the oven and heat them slowly to a temperature near to that which is expected to induce failure on quenching. after a period of at least 10 min for stabilization of temperature of the test pieces or components, record the test temperature. transfer the test pieces smoothly and quickly to the water bath. after a minimum period of two minutes, remove the test-pieces or components from the bath and dry them at (120 10) c for at least 2 h, cool and allow them to equilibrate at room temperature. if the dye test is to be used, subject them to the test in accordance with en 623-1 and examine them for the development of surface cracks. if the strength test is to be performed, fracture the test pieces in accordance with en