SIST-TS CEN/TS 1159-4:2005
(Main)Advanced technical ceramics - Ceramic composites - Thermophysical properties - Part 4: Determination of thermal conductivity
Advanced technical ceramics - Ceramic composites - Thermophysical properties - Part 4: Determination of thermal conductivity
This document describes a method for the determination of the thermal conductivity of ceramic matrix composites with continuous fibre reinforcement. This method applies to all ceramic matrix composites with a fibre reinforcement, unidirectional (1D), bidirectional (2D), and tridirectional (xD, with 2 < x 3) as defined in ENV 13233, submitted to a heat flux along one principal axis of anisotropy.
The experimental conditions are such that the material behaves in an homogeneous manner for each of its axis of anisotropy and that the heat transfer occurs only by thermal conduction. The method is applicable to materials which are physically and chemically stable during the measurement.
Contrary to other methods of direct measurement which permit only to determine a value of the thermal conductivity averaged over an interval of temperature, the method described in this document, based on an adequate exploitation of the temperature record, allows to determine with a good accuracy the thermal conductivity at a defined temperature. This is more interesting since the variation of the thermal conductivity with the temperature is non-linear, which is generally the case for CMC's.
NOTE It is also possible to calculate the conductivity of CMC's by an indirect method using the following equation:
= a pb Cp
where
is the thermal conductivity;
a is the thermal diffusivity;
pb is the bulk density;
Cp is the specific heat capacity.
Hochleistungskeramik - Keramische Verbundwerkstoffe - Thermophysikalische Eigenschaften - Teil 4: Bestimmung der Wärmeleitfähigkeit
Céramiques techniques avancées - Composites céramiques, propriétés thermophysiques - Partie 4: Détermination de la conductivité thermique
Sodobna tehnična keramika – Keramični kompoziti – Termofizikalne lastnosti – 4. del: Določanje toplotne prevodnosti
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-januar-2005
6RGREQDWHKQLþQDNHUDPLND±.HUDPLþQLNRPSR]LWL±7HUPRIL]LNDOQHODVWQRVWL±
GHO 'RORþDQMHWRSORWQHSUHYRGQRVWL
Advanced technical ceramics - Ceramic composites - Thermophysical properties - Part 4:
Determination of thermal conductivity
Hochleistungskeramik - Keramische Verbundwerkstoffe - Thermophysikalische
Eigenschaften - Teil 4: Bestimmung der Wärmeleitfähigkeit
Céramiques techniques avancées - Composites céramiques, propriétés
thermophysiques - Partie 4: Détermination de la conductivité thermique
Ta slovenski standard je istoveten z: CEN/TS 1159-4:2004
ICS:
81.060.30 Sodobna keramika Advanced ceramics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
TECHNICAL SPECIFICATION
CEN/TS 1159-4
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
July 2004
ICS 81.060.30
English version
Advanced technical ceramics - Ceramic composites -
Thermophysical properties - Part 4: Determination of thermal
conductivity
This Technical Specification (CEN/TS) was approved by CEN on 13 July 2001 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 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 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, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
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COMITÉ EUROPÉEN DE NORMALISATION
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Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2004 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 1159-4:2004: E
worldwide for CEN national Members.
Contents Page
Foreword. 3
1 Scope. 5
2 Normative references . 5
3 Terms and definitions. 5
4 Significance and use . 6
5 Principle . 6
6 Apparatus . 8
7 Test specimens dimensions . 9
8 Test specimens preparation . 10
9 Number of test specimens . 11
10 Test procedure . 11
11 Test validity . 14
12 Results . 14
13 Test report . 15
Foreword
This document CEN/TS 1159-4:2004 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 January 2005, and conflicting national standards
shall be withdrawn at the latest by January 2005.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to announce this Technical 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 United Kingdom.
EN 1159 Advanced technical ceramics — Ceramic composites. Thermophysical properties consists of
four parts:
Part 1: Determination of thermal expansion;
Part 2: Determination of thermal diffusivity;
Part 3: Determination of specific heat capacity;
Part 4: Determination of thermal conductivity.
Part 4 is a Technical Specification.
Introduction
Statement on patent use
Attention is drawn to the fact that compliance with this document may involve the use of a patented
process, which is the "Process for determining the thermal conductivity of a material at high
temperature and conductimeter for implementation of this process", given in this document.
CEN takes no position concerning the evidence, validity and scope of this patent right. The holder of
the patent has provided a statement concerning use of the patented process. The holder of this patent
right has assured CEN that he is willing to negotiate licences under reasonable and non-
discriminatory terms and conditions with the applicants throughout the world. In this respect, the
statement of the holder of this patent right is registered with CEN. Further information may be
obtained from:
European Aeronautic Defence and Space Company EADS France S.A.S.
Mr Jean-Marc THOMAS –
Avenue du Général Niox – BP 11
33 165 Saint-Médard-en-Jalles cedex - FRANCE
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights other than those identified above. CEN shall not be held responsible for identifying any
or all such patent rights.
1 Scope
This document describes a method for the determination of the thermal conductivity of ceramic matrix
composites with continuous fibre reinforcement. This method applies to all ceramic matrix composites
with a fibre reinforcement, unidirectional (1D), bidirectional (2D), and tridirectional (xD, with 2 < x ≤ 3)
as defined in ENV 13233, submitted to a heat flux along one principal axis of anisotropy.
The experimental conditions are such that the material behaves in an homogeneous manner for each
of its axis of anisotropy and that the heat transfer occurs only by thermal conduction. The method is
applicable to materials which are physically and chemically stable during the measurement.
Contrary to other methods of direct measurement which permit only to determine a value of the
thermal conductivity averaged over an interval of temperature, the method described in this document,
based on an adequate exploitation of the temperature record, allows to determine with a good
accuracy the thermal conductivity at a defined temperature. This is more interesting since the
variation of the thermal conductivity with the temperature is non-linear, which is generally the case for
CMC's.
NOTE It is also possible to calculate the conductivity of CMC's by an indirect method using the following
equation:
λ = a × p × C
b p
where
λ is the thermal conductivity;
a is the thermal diffusivity;
p is the bulk density;
b
C is the specific heat capacity.
p
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.
ENV 13233, Advanced technical ceramics —– Ceramic composites — Notations and symbols
ISO 3611, Micrometer callipers for external measurements
3 Terms and definitions
For the purposes of this document, the terms and definition and symbols given in ENV 13233 and the
following apply.
3.1
heat flow, ΦΦΦΦ
quantity of heat transferred per unit time
3.2
density of heat flow, φ
heat flow per unit area
3.3
representative volume element
minimum volume that is representative of the material considered
3.4
temperature of the hot face, T
h
temperature of the face designated the hot face in Figures 1 and 2
3.5
temperature of the cold face, T
c
temperature of the face designated the cold face in Figures 1 and 2
3.6
temperature of the internal wall, T
inf
temperature of the wall designated the internal wall in Figure 4
3.7
temperature gradient, ∆T/h
ratio of the temperature difference ∆T = T – T between the two parallel faces of the test specimen to
h c
the distance between the two faces, h
3.8
thermal conductivity, λ
ratio of the density of heat flow to the temperature gradient
4 Significance and use
Methods of measurement of the thermal conductivity (either standardised or not) are in the majority
dedicated to the characterisation of insulating materials with λ values lower than or equal to
-1 -1
1 W.m .K . Indeed, a principal feature of all direct methods of determination of the thermal
conductivity consists in creating a thermal gradient in the test specimen, which explains why such
methods are successful when used with insulating materials.
Ceramic matrix composites however, have values of thermal conductivity at low and moderate
-1 -1 -1 -1
temperatures in the range of 15 W.m .K to 100 W.m .K . These values decrease with increasing
temperature, but still remain relatively high. This behaviour would require the use of very thick test
specimens, in order to achieve a sufficient thermal gradient, a requirement which cannot usually be
met. In this case an indirect method such as measurement of the thermal diffusivity, should be used.
5 Principle
The variation of the thermal conductivity of the CMC's with temperature is generally non linear over
the range of temperature currently considered.
This document describes a method for the determination of the thermal conductivity within an
increment of temperature assuming that the thermal conductivity is linear within this increment. This
increment depends upon the material tested. In the first instance it will be set at a value of 100 °C.
The front face (hot face) of a test specimen is exposed to a uniformly distributed temperature T using
h
a heating plate. After the system reaches equilibrium, the temperature T of the rear face (cold face) is
c
measured as well as the heat flow at this face (see Figures 1 and 2). In order to achieve good
conditions of thermal insulation of the lateral faces, it is recommended to use a "guarded test
specimen" as depicted in Figures 1 and 2.
Key
1 Tool to secure good contact between the test specimen, 6 Heating plate
the heat-flow measurement system and the heating plate 7 Area of heat transfer
2 Heat-flow measurement system 8 Guarded test specimen
3 Thermocouples 9 Lateral insulation
4 Lateral insulation 10 Cold face, T
c
5 Hot face, T
h
Figure 1 — General arrangement of the apparatus for measurement of the temperature on the
two faces by thermocouples
Key
1 Tool to secure good contact between the test specimen, 7 Heating plate
the heat-flow measurement system and the heating plate 8 Temperature measurement with
2 Temperature measurement with a pyrometer a pyrometer
3 Heat-flow measurement system 9 Guarded test specimen
4 Area or heat transfer 10 Lateral insulation
5 Lateral insulation 11 Cold face, T
c
6 Hot face, T
h
Figure 2 — General arrangement of the apparatus for measurement of the temperature on the
two faces by pyrometry
Considering the accuracy of the temperature measurements on the hot and the cold faces, a
minimum difference of 100 °C between these two faces is recommended.
6 Apparatus
All the components described below shall be made from materials which will not react with the test
specimen:
heating source: heating plate with a flat surface, with which a temperature uniformity to within
± 5 °C over the range of temperatures measured shall be achievable;
gas-tight cooled chamber allowing to maintain an inert or vacuum atmosphere;
temperature measuring equipment, with thermocouples, preferably in accordance with EN 60584-
1 and EN 60584-2, or with an optical pyrometer. Pyrometers or thermocouples which are not
covered by EN 60584-1 and EN 60584-2 shall be appropriately calibrated;
heat flow meter if used;
NOTE If a heat flow meter is not used, Clause 10.4 applies.
tool to secure a good contact between the heat-flow measurement system, the test specimen and
the heating plate. This tool shall not generate a thermal gradient that could alter the
determination of the thermal conductivity;
devices to measure the dimensions of the are
...
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