ISO 22007-7:2023

INTERNATIONAL ISO
STANDARD 22007-7
First edition
2023-04
Plastics — Determination of thermal
conductivity and thermal diffusivity —
Part 7:
Transient measurement of thermal
effusivity using a plane heat source
Plastiques — Détermination de la conductivité thermique et de la
diffusivité thermique —
Partie 7: Mesure transitoire de l'effusivité thermique à l'aide d'une
source de chaleur plane
Reference number
© ISO 2023
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Apparatus . 2
6 Test specimens . 2
6.1 Configuration A: Rod-shaped specimens having a thermal effusivity above
1/2 -2 -1
1 000 W·s ·m ·K . 2
1/2 -2 -1
6.2 Configuration B: Specimens of thermal effusivity below 1 000 W·s ·m ·K
completely embedding the probe . 3
6.3 Specimen preparation . 3
7 Procedure .4
8 Calculation of thermal effusivity . 6
8.1 Computations . 6
8.2 Single-sided setup . 9
9 Verification procedures .9
9.1 Calibration of apparatus . 9
9.2 Verification of apparatus . 9
10 Precision and bias .10
11 Test report .10
Annex A (informative) Example of testing a homogeneous, anisotropic rod .11
Annex B (informative) Example of testing a stacked, anisotropic Rod .14
Bibliography .16
iii
Foreword
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iv
Introduction
[1]-[4]
The developments of so-called transient measurement methods since the 1990’s , has provided the
scientific community with tools capable of quickly and accurately testing thermophysical properties of
[5]-[9]
small- and irregular-shaped specimens .
A regularly-shaped probe (square, rectangle, circle, ellipse, etc.), consisting of a metal heating pattern,
is sandwiched between two pieces of a specimen material. The probe simultaneously functions as
an ohmic heater – providing approximately equal heat production per unit area across its surface –
and also as a resistance thermometer. In experimental configurations discussed in the following,
the thermal effusivity in the normal direction to the probe surface can be estimated from a single
[2]-[4],[9]
experiment .
The specimens that can be tested using this method are homogeneous isotropic specimens and
[10]
homogeneous anisotropic specimens (with uniaxial structure ). The effusivity is obtained for the
bulk of the specimen material, because of the possibility to eliminate the influence from the thermal
contact resistance between the probe sensing metal pattern and the substrate surface.
Some experimental features on testing thermal effusivity with present approach are, first, the ability
to significantly reduce the overall specimen geometry size. Secondly, the normal-direction heat flow
allows for analysing specimen geometries of major industrial importance, for instance, a layered- or
composite structure, with repeated intrinsic geometric features.
One industrial application considered is the TIM-stacked setup, consisting of a repeated structure
incorporating thermal interface material (TIM) layers between solid slabs. The many drawbacks and
uncertainties of testing a single-layer TIM layer applied in alternative measurement approaches, is here
replaced with an experimental stack setup allowing to precisely measure the final application intended
for a specific TIM layer material.
Parameters to consider when testing thermal effusivity in a rod-shaped specimen are: differences in
probe cross-section and rod specimen cross-section. At least a rough estimation on the volumetric
specific heat of the specimen is also advantageous to know, when estimating the probing depth
(important for controlling of the transient experiment). In addition, potential effects of heat losses to
surroundings should also be assessed.
v
INTERNATIONAL STANDARD ISO 22007-7:2023(E)
Plastics — Determination of thermal conductivity and
thermal diffusivity —
Part 7:
Transient measurement of thermal effusivity using a plane
heat source
1 Scope
This document specifies a method for the determination of the thermal effusivity.
This document is applicable to materials with thermal effusivity in the approximate range
1/2 −2 −1 1/2 -2 -1
40 W⋅s ⋅m ⋅K < n
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
ISO 22007-1, Plastics — Determination of thermal conductivity and thermal diffusivity — Part 1: General
principles
ISO 22007-2, Plastics — Determination of thermal conductivity and thermal diffusivity — Part 2: Transient
plane heat source (hot disc) method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 22007-1, ISO 22007-2 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
thermal effusivity
b
quantity, possible to express in terms of the square root of the product of the material’s bulk thermal
conductivity and volumetric specific heat of a specimen, bc=⋅λρ
p
Note 1 to entry: In its most general form, this is a second-rank tensor property.
Note 2 to entry: The thermal effusivity in the normal direction to the plane of the probe is represented by the
scalar b .
n
1/2 -2 -1
Note 3 to entry: It is expressed in W⋅s ⋅m ⋅K .
4 Principle
4.1 A specimen with an internally-positioned thermal effusivity probe – assumed to have a negligible
heat capacity – is set to thermally equilibrate at a certain temperature. A measurement is conducted by
applying a single-step heat pulse (generated by Ohmic heating). A temperature field around the probe
develops with time (from the onset of the single-step heat pulse). The temperature increase in the probe
is recorded at different time points.
4.2 The probe represents a combined heater and temperature sensor – which is sometimes referred
to as a self-heated sensor. The temperature vs. time response is then analysed for the model developed
and the assumed boundary conditions. Two principally different configurations are possible for testing
normal-direction thermal effusivity.
4.3 Configuration A: Specimens and an experimental setup designed to allow the heat flow to occur
essentially in a 1-dimensional manner, in the normal direction from the probe, for a comparably long
period of experimental time. It is suitable for small and narrow specimens with a thermal effusivity
1/2 -2 -1
above approximately 1 000 W⋅s ⋅m ⋅K .
4.4 Configuration B: Specimens and an experimental setup designed to allow the heat flow to occur
essentially in a 1-dimensional manner, in the normal direction from the probe, for a comparably short
period of experimental time. It is suitable for large and wide specimens having a thermal effusivity less
1/2 -2 -1
than approxim
...