SIST EN 820-3:2005

SLOVENSKI STANDARD
01-januar-2005
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Advanced technical ceramics - Methods of testing monolithic ceramics -
Thermomechanical properties - Part 3: Determination of resistance to thermal shock by
water quenching
Hochleistungskeramik - Prüfverfahren für monolithische Keramik - Thermomechanische
Eigenschaften - Teil 3: Bestimmung der Thermoschockbeständigkeit mit dem
Wasserabschreckversuch
Céramiques techniques avancées - Méthodes d'essai des céramiques monolithiques -
Propriétés thermomécaniques - Partie 3 : Détermination de la résistance au choc
thermique par la méthode de trempe a l'eau
Ta slovenski standard je istoveten z: EN 820-3:2004
ICS:
81.060.30 Sodobna keramika Advanced ceramics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 820-3
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2004
ICS 81.060.30 Supersedes ENV 820-3:1993
English version
Advanced technical ceramics - Methods of testing monolithic
ceramics - Thermomechanical properties - Part 3: Determination
of resistance to thermal shock by water quenching
Céramiques techniques avancées - Céramiques Hochleistungskeramik - Prüfverfahren für monolithische
monolithiques - Propriétés thermomécaniques - Partie 3: Keramik - Thermomechanische Eigenschaften - Teil 3:
Détermination de la résistance au choc thermique par la Bestimmung der Thermoschockbeständigkeit mit dem
méthode de trempe à l'eau Wasserabschreckversuch
This 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,
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Slovenia, Spain, Sweden, Switzerland and United Kingdom.
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© 2004 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 820-3:2004: E
worldwide for CEN national Members.

Contents
page
Foreword.3
1 Scope.4
2 Normative references.4
3 Principle.4
4 Apparatus.5
5 Test pieces.5
6 Procedure.6
7 Test report.7
Annex A (informative)  Introduction to thermal shock behaviour .9
Bibliography .12

Foreword
This 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 temperatures
Part 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.

1 Scope
This 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.
NOTE This 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.
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, 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 tests
EN 843-1, Advanced technical ceramics — Monolithic ceramics — Mechanical properties at room
temperatures — Part 1: Determination of flexural strength
EN 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)
3 Principle
A 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 1 Dye 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 2 By 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, ∆T . This temperature difference can be estimated
c
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.
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.
4 Apparatus
The 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.
NOTE The 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.
5 Test pieces
Test 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.
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 1 Test 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 2 The 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 3 The 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.
6 Procedure
Clean and dry the test-pieces at (120 ± 10) °C for 2 h in an oven. Allow to equilibrate
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