ISO 13826:2013

Metallic and other inorganic coatings - Determination of thermal diffusivity of thermally sprayed ceramic coatings by laser flash method

ISO 13826:2013 specifies a test method of thermal diffusivity of thermally sprayed ceramic coatings using laser technology. This test method is applicable to self-standing thermally sprayed ceramic coatings of thickness between 0,8 mm to 2 mm, deposited by various thermal spray processes and removed from the substrate. Thermal diffusivity values ranging from 10−7 m2/s to 10−4 m2/s are measurable by this test method for temperature range from 300 K to 1500 K.

Revêtements métalliques et autres revêtements inorganiques — Détermination de la diffusivité thermique des revêtements céramiques obtenus par projection thermique par la méthode flash laser

General Information

• Status: Published
• Publication Date: 07-Jan-2013
• ICS: 25.220.20 - Surface treatment
• Technical Committee: ISO/TC 107 - Metallic and other inorganic coatings
• Drafting Committee: ISO/TC 107/WG 1 - Thermal spraying
• Current Stage: 9093 - International Standard confirmed
• Start Date: 06-Mar-2024
• Completion Date: 13-Dec-2025

Overview

ISO 13826:2013 - "Metallic and other inorganic coatings - Determination of thermal diffusivity of thermally sprayed ceramic coatings by laser flash method" specifies a laser‑flash test method to measure the thermal diffusivity of self‑standing thermally sprayed ceramic coatings. The procedure applies to detached coating discs (typically 10 mm diameter) with thicknesses between 0.8 mm and 2 mm, and covers measurable diffusivity values from 10−7 m2/s to 10−4 m2/s over a temperature range of 300 K to 1500 K. Results are used with density and specific heat data to derive thermal conductivity for engineering design.

Key topics and technical requirements

• Test principle: Apply a short, high‑intensity heat pulse to the front face and record the rear‑face temperature transient; determine the half‑rise time (t1/2) and compute thermal diffusivity.
• Specimen: Thin circular discs, faces flat and parallel within 0.5% of thickness; coatings removed from substrate (methods described for separation).
• Apparatus essentials:
  • Uniform flash source (Nd glass laser preferred) with pulse FWHM < 1.0 ms.
  • Environmental control (vacuum or inert atmosphere) and heater capable up to test temperatures.
  • Detector: non‑contact infrared preferred; detector/conditioning with adequate response (able to resolve ~0.05 °C and response time << 2% of t1/2).
  • Data acquisition: high sampling frequency and ≥12‑bit A/D resolution.
• Corrections and calculations:
  • Use half‑rise time method with correction factor ω and apply corrections for heat loss, finite pulse time, and sensor (thermocouple) response (Annex A).
  • Reported values must include specimen geometry, density, temperature, laser source, detector type, ∆T and t1/2, and statistical repeatability.

Applications

• Characterizing thermal barrier coatings (TBCs) and other thermally sprayed ceramics for aerospace, gas turbines, power generation, and automotive components.
• Designing insulation and thermal protection systems by providing diffusivity (and thus conductivity) used to:
  • Calculate required coating thickness to protect metallic substrates and superalloys.
  • Model heat transfer, cooling systems, and life‑cycle thermal performance.
• Quality control and R&D for thermal spray producers, materials labs, and coating development.

Who uses this standard

• Materials scientists and test laboratories performing thermal property measurements.
• Coating manufacturers and process engineers in thermal spray industries.
• Design engineers for turbines, engines, and industrial furnaces requiring validated thermal property data.

Related standards (if applicable)

• Complementary ISO documents and industry standards covering thermal spray processes, coating characterization, and measurement of related thermal properties (density, specific heat, thermal conductivity) are typically used alongside ISO 13826:2013 to deliver complete thermal performance data.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 13826
First edition
2013-01-15
Metallic and other inorganic
coatings — Determination of thermal
diffusivity of thermally sprayed
ceramic coatings by laser flash method
Revêtements métalliques et autres revêtements inorganiques —
Détermination de la diffusivité thermique des revêtements céramiques
obtenus par projection thermique par la méthode flash laser
Reference number
©
ISO 2013
© ISO 2013
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any
means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the
address below or ISO’s member body in the country of the requester.
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Tel. + 41 22 749 01 11
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Published in Switzerland
ii © ISO 2013 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Terms and definitions . 1
3 Principle of test method . 1
4 Test method . 2
4.1 General . 2
4.2 Apparatus . 2
5 Test specimen (disc) . 3
6 Procedures . 3
7 Calculation of thermal diffusivity . 4
8 Test report . 4
Annex A (informative) Calculations of thermal diffusivity after appropriate corrections .6
Bibliography .11
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 13826 was prepared by Technical Committee ISO/TC 107, Metallic and other inorganic coatings.
iv © ISO 2013 – All rights reserved

Introduction
Thermally sprayed ceramic coatings provide protection against high-temperature corrosion, erosion and
wear; they can also change the appearance, electrical or tribological properties of the surface, replace
worn material, etc. Thermal barrier coatings (TBCs) are typical examples of such ceramic coatings.
Thermal diffusivity data of thermally sprayed ceramic coatings are measured by the laser flash method.
The data are used to calculate thermal conductivity when provided with density and specific heat
capacity data.
Thermal diffusivity and thermal conductivity are significant properties of such thermally sprayed
coatings when designing for thermal insulation, thermal isolation, efficient heat transfer and cooling
systems. It is used by designers to calculate appropriate thickness needed to protect the metallic
components and thus to determine the maximum temperature to which super-alloys with the thermally
sprayed ceramic coatings could be exposed.
This International Standard gives guidelines for the determination of thermal diffusivity of thermally
sprayed ceramic coatings by the laser flash method.
INTERNATIONAL STANDARD ISO 13826:2013(E)
Metallic and other inorganic coatings — Determination of
thermal diffusivity of thermally sprayed ceramic coatings
by laser flash method
1 Scope
This International Standard specifies a test method of thermal diffusivity of thermally sprayed ceramic
coatings using laser technology.
This test method is applicable to self-standing thermally sprayed ceramic coatings of thickness between
0,8 mm to 2 mm, deposited by various thermal spray processes and removed from the substrate.
−7 2 −4 2
Thermal diffusivity values ranging from 10 m /s to 10 m /s are measurable by this test method for
temperature range from 300 K to 1500 K.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
thermal diffusivity
α
ratio of thermal conductivity to specific heat capacity per unit mass, which describes the rate at which
heat flows through a material, expressed in m /s
2.2
half-rise time
t
1/2
time needed for the rear surface temperature to reach one-half of its maximum value or half-rise time,
expressed in s
3 Principle of test method
The laser flash method is based on the measurement of the temperature profile of the rear surface of the
sample when a pulsed laser illuminates the front surface, thus avoiding interference between the sensor,
recording the temperature rise on the rear surface, and heat source.
Thermal diffusivity shall be measured by applying a high-intensity short-duration heat pulse to one
face of a parallel-sided homogeneous test part, monitoring the temperature rise at the opposite face as
[1]
a function of time, and determining the transient half-rise time (t ).
1/2
Thermal diffusivity is calculated as
 
L
αω=   (1)
 
t
12/
 
where
ω is the thermal diffusivity correction factor;
L is the thickness of the specimen, m;
4 Test method
4.1 General
The laser flash method determines the thermal diffusivity for coatings on known substrates using
small disc-shaped specimens. Covering an application range from 300 K to 1500 K, it fulfils the needs of
thermal classification for almost any material and system problem, including ceramic thermal barrier
coatings. The laser flash method is currently the most widely accepted method for precise measurement
[2]
of the thermal diffusivity.
4.2 Apparatus
The essential features of a laser flash diffusivity unit are shown in Figure 1.
Key
1 Laser
2 Vacuum or inert atmosphere
3 Sample
4 Heater
5 Detector
6 AD-converter and amplifier
7 Digital Data Acquisition System
8 Printer
9 PC
10 Visual Display
Figure 1 — Schematic diagram of laser flash diffusivity unit
The window is of any transparent material and the specimen holder is ceramic or any other material
with lower thermal conductivity than the sample.
4.2.1 Flash source
It is essential for the laser source to be uniform over the entire surface of the specimen. For this reason,
Neodymium (Nd) glass laser as a flash source is preferred. The pulse width, FWHM (full width at half
maximum), should be shorter than 1,0 ms.
2 © ISO 2013 – All rights reserved

4.2.2 Heater
The heater shall be of adequate dimension to heat and fix within the temperature range. It shall be
capable of having a suitable temperature control facility prior to and during a test to be less than 4 % of
the maximum temperature rise.
4.2.3 Environmental control cabinet
The cabinet, capable of measuring below and above room temperature, may be a vacuum chamber
or contain inert gas for operation in a protective atmosphere and is fitted with a window, which is
transparent to the flash source. A second window for detection of the rea
...