ISO 22680:2020 pdf download

ISO 22680:2020 pdf download.Metallic and other inorganic coatings — Measurement of the linear thermal expansion coefficient of thermal barrier coatings
1 Scope
This document specifies a method for measuring the reproducible linear thermal expansion coefficient of ceramic top coats (TCs) for thermal barrier coatings (TBCs) up to 1 300 °C.
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 17562, Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for linear hermal expansion of monolithic ceramics by push-rod technique
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 17139 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
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3.1 thermal barrier coating
TBC
two-layer coating consisting of a metallic bond coat (BC) and a ceramic top coat (TC), in order to reduce heat transfer from outside the top coat through the coating to the substrate
Note 1 to entry: See Figure 1.
4 Principle
Ceramic TCs exhibit an unstable linear thermal expansion coefficient during the initial few heating cycles, as shown in Annex A. Therefore, the measurement shall be repeated until the reproducible linear thermal expansion coefficient is obtained. The fundamental procedures are shown in Figure 2. A specimen of a TC, prepared as described in Clause 6, that constitutes a TBC is heated to a specified temperature at a controlled heating rate. During the heating, the linear thermal expansion coefficients of the specimen are measured based on the change of the length and the temperature of the specimen. The measurement shall be repeated until the criterion to finish the measurement mentioned in Clause 7 is satisfied.
5.1 Apparatus
An example of the apparatus for measuring the linear thermal expansion coefficient is schematically shown in Figure 3. The apparatus shall be specified in accordance with ISO 17139 and shall be calibrated using the reference specimen (see 6.2). Care shall be taken to ensure that the thermocouple tip is in close proximity to the specimen in accordance with ISO 17562.