ISO 23458:2020

Fine ceramics (advanced ceramics, advanced technical ceramics) - Test method for determining thermal expansion coefficient and residual stress of CVD ceramic coatings

This document specifies a test method for determining thermal expansion coefficient up to 2 300 K and the residual stress of chemical vapour deposition (CVD) ceramic coatings (thickness > 0,03 mm) at room temperature. Procedures for test piece preparation, test modes, heat rate, data collection, property calculations and reporting procedures are given. This document applies to CVD ceramic coatings on metal or ceramic substrates. This test method can be used for material research, quality control, characterization and design data-generation purposes.

Titre manque

General Information

• Status: Published
• Publication Date: 11-May-2020
• ICS: 81.060.30 - Advanced ceramics
• Technical Committee: ISO/TC 206 - Fine ceramics
• Drafting Committee: ISO/TC 206/WG 10 - Coatings
• Current Stage: 9093 - International Standard confirmed
• Start Date: 25-Sep-2025
• Completion Date: 13-Dec-2025

Overview

ISO 23458:2020 specifies a test method for determining the linear thermal expansion coefficient (up to 2 300 K) and the residual stress (evaluated at room temperature) of chemical vapour deposition (CVD) ceramic coatings thicker than 0.03 mm. The standard covers specimen preparation, test modes, heating/cooling rates, apparatus and measurement accuracy, data collection, calculation procedures and reporting requirements. It applies to CVD ceramic coatings on metal or ceramic substrates and is intended for material research, quality control, characterization and design data generation.

Key topics and technical requirements

• Measurement principle: a relative method comparing a coated composite bar and an uncoated substrate bar to deduce the coating expansion coefficient and residual stress via geometric compatibility and elastic equilibrium models.
• Temperature range: thermal expansion coefficient determined up to 2 300 K; residual stress reported at room temperature.
• Specimens: symmetric coating configurations allowed (two-face, four-face, around/cylindrical). Recommended specimen sizes: length 30–50 mm, cross-section ~5 mm, coating thickness > 0.03 mm, and thickness ratio h/H (or h/D) < 1/4. A minimum of three pairs of test pieces is required for comparison.
• Apparatus & sensors:
  • Furnace capable of controlled atmosphere and temperature control within 1% of mean temperature.
  • Thermocouples per IEC 60584-1; for >2 000 K, infrared detectors or suitable devices may be used.
  • Displacement measurement accuracy better than 0.0001 mm; recording error ≤ 1%. Minimum data collection frequency 15 Hz (50 Hz recommended response).
  • Dimensional measuring tools: vernier (ISO 3611) with precision 0.02 mm or better; coating thickness via optical microscope at ×1 000 or better.
• Calculations: thermal expansion coefficient (α) from measured length changes and known substrate properties (ISO 17139 referenced); residual stress (σ) computed from α, elastic moduli, coating-to-substrate area ratio and coating temperature history (elastic modulus measurement referenced to ISO 19603).
• Reporting: procedures for documenting specimen geometry, measurement conditions, apparatus, data, calculations and uncertainties.

Applications and users

ISO 23458:2020 is used by:

• Materials scientists and ceramic engineers studying CVD ceramic thermal behavior
• Coating manufacturers and process engineers for quality control and process validation
• Test laboratories performing characterization and certification of advanced ceramic coatings
• Product designers and simulation teams needing accurate thermal and stress input data for components with CVD coatings

Keywords: ISO 23458:2020, CVD ceramic coatings, thermal expansion coefficient, residual stress, test method, fine ceramics, advanced ceramics, characterization, quality control.

Related standards

• ISO 17139 - thermophysical properties / thermal expansion testing
• ISO 19603 - elastic modulus and bending strength of thick coatings
• ISO 3611 - dimensional measuring equipment (micrometers)
• IEC 60584-1 - thermocouples (EMF specs and tolerances)

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 23458
First edition
2020-05
Fine ceramics (advanced ceramics,
advanced technical ceramics) — Test
method for determining thermal
expansion coefficient and residual
stress of CVD ceramic coatings
Reference number
©
ISO 2020
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
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ii © ISO 2020 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Apparatus . 2
5.1 General . 2
5.2 Heating and cooling device. 3
5.3 Temperature measurement . 3
5.4 Test piece mounting . 3
5.5 Data recording system . 4
5.6 Dimensional measuring devices . 4
6 Specimens . 4
6.1 Test piece . 4
6.2 Dimensions . 5
6.3 Test piece preparation . 6
6.3.1 General. 6
6.3.2 Test piece handling and storage . 6
6.3.3 Number of test pieces . 6
7 Test procedure . 6
7.1 Measurement of the test piece dimensions . 6
7.2 Measurement of the elastic modulus . 6
7.3 Measurement of the thermal expansion coefficient of CVD coatings . 6
7.4 Calculation of the residual stress in CVD coatings . 7
8 Calculation . 7
8.1 Thermal expansion coefficient of the CVD ceramic coatings, α . 7
c
8.2 Residual stress in CVD coatings, σ . 7
c
9 Test report . 8
Bibliography . 9
Foreword
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electrotechnical standardization.
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described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
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expressions related to conformity assessment, as well as information about ISO's adherence to the
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iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 206, Fine ceramics.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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iv © ISO 2020 – All rights reserved

INTERNATIONAL STANDARD ISO 23458:2020(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Test method for determining thermal
expansion coefficient and residual stress of CVD ceramic
coatings
1 Scope
This document specifies a test method for determining thermal expansion coefficient up to 2 300 K
and the residual stress of chemical vapour deposition (CVD) ceramic coatings (thickness > 0,03 mm)
at room temperature. Procedures for test piece preparation, test modes, heat rate, data collection,
property calculations and reporting procedures are given.
This document applies to CVD ceramic coatings on metal or ceramic substrates. This test method can
be used for material research, quality control, characterization and design data-generation purposes.
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 3611, Geometrical product specifications (GPS) — Dimensional measuring equipment: Micrometers for
external measurements — Design and metrological characteristics
ISO 17139, Fine ceramics (advanced ceramics, advanced technical ceramics) — Thermophysical properties
of ceramic composites — Determination of thermal expansion
ISO 19603, Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for determining
elastic modulus and bending strength of thick ceramic coatings
IEC 60584-1, Thermocouples — Part 1: EMF specifications and tolerances
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
relative method
indirect test method to obtain the measured parameter
Note 1 to entry: The expected parameter A is usually difficult to measure directly, but parameters B and C are
known parameters or easy to obtain. If the analytical relationship of A = f (B, C) is established, the parameter A
can be calculated.
3.2
linear thermal expansion
positive or negative change in one dimension that occurs when a material is subjected to a change in
temperature
4 Principle
The deformation of a coated bar during heating or cooling involves two effect factors, i.e. thermal
expansion coefficient and residual stress in the coating and the substrate. The thermal expansion
coefficient is a material characteristic. However, the residual stresses in the coating are not only due to
a material property but depend also on the size of the component and the cross-sectional area ratio of
the coating and substrate.
The thermal
...