1、 ISO 2016 Metallic and other inorganic coatings Determination of thermal conductivity of thermal barrier coatings Revtements mtalliques et autres revtements inorganiques Dtermination de la conductivit thermique des revtements barrires thermiques INTERNATIONAL STANDARD ISO 18555 First edition 2016-02
2、-01 Reference number ISO 18555:2016(E) ISO 18555:2016(E)ii ISO 2016 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2016, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, el
3、ectronic 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 ISOs member body in the country of the requester. ISO copyright office Ch. de Blandonnet 8 CP 401 CH-1214 V
4、ernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyrightiso.org www.iso.org ISO 18555:2016(E)Foreword iv Introduction v 1 Scope . 1 2 Normative references 1 3 T erms and definitions . 1 4 Principle 4 5 Apparatus for measuring thermal diffusivity 4 6 Specimen . 5 6.1 Shape and
5、 dimensions 5 6.2 Surface treatment . 7 7 Measuring procedure 7 7.1 Specimen thickness . 7 7.2 Thermal diffusivity 7 7.2.1 Measurement of temperature-rise curve 7 7.2.2 Calculation of thermal diffusivity of substrate . 7 7.2.3 Calculation of thermal diffusivities of BC and TC 7 7.3 Specific heat cap
6、acity .10 7.4 Bulk density 10 8 Thermal conductivities of BC and TC .11 9 Report .11 9.1 Items to be reported 11 9.2 Additional items to be selected for the report 12 Annex A (informative) Areal heat diffusion time method .13 Annex B (informative) Examples of theoretical temperature-rise curves .16
7、Bibliography .18 ISO 2016 All rights reserved iii Contents Page ISO 18555:2016(E) 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 throug
8、h 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 collaborat
9、es closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval cr
10、iteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives). Attention is drawn to the possibility that some of the elements of this document may be the subject
11、 of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents). Any trade n
12、ame used in this document is information given for the convenience of users and does not constitute an endorsement. For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Techn
13、ical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information The committee responsible for this document is ISO/TC 107, Metallic and other inorganic coatings.iv ISO 2016 All rights reserved ISO 18555:2016(E) Introduction Thermal barrier coatings are highly advanced materi
14、al systems. They are generally applied to surfaces of hot-section components made of nickel or cobalt-based superalloys, such as combustors, blades, vanes of power-generation gas turbines in thermal power plants and aero-engines operated at elevated temperatures. The function of these coatings is to
15、 protect metallic components for extended periods at elevated temperatures by employing thermally insulating materials which can sustain an appreciable temperature difference between load bearing alloys and coating surfaces. These coatings permit the high-temperature operation by shielding these com
16、ponents, thereby extending their lives. Although thermal conductivity is one of the most important properties of thermal barrier coatings, the existing International Standard (ISO 18755:2005) includes only the method for determining the thermal diffusivity of monolithic ceramics, regarding the heat
17、conduction in thermal barrier coating. ISO 2016 All rights reserved v Metallic and other inorganic coatings Determination of thermal conductivity of thermal barrier coatings 1 Scope This International Standard specifies the method for determining the thermal conductivities of thermal barrier coating
18、s consisting of metallic bond coats and ceramic top coats, in a direction normal to the coating surface, at room temperature. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated referenc
19、es, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 1463, Metallic and oxide coatings Measurement of coating thickness Microscopical method ISO 18755:2005, Fine ceramics (advanced ceramics, advanced technic
20、al ceramics) Determination of thermal diffusivity of monolithic ceramics by laser flash method EN 821-3, Advanced technical ceramics Monolithic ceramics. Thermophysical properties Part 3: Determination of specific heat capacity ASTM E1269-11, Standard Test Method for Determining Specific Heat Capaci
21、ty by Differential Scanning Calorimetry 3 T erms a nd definiti ons For the purpose of this standard, the terms and definitions given in ISO 18755:2005 and the following apply. 3.1 thermal barrier coating TBC two-layer coating consisting of a metallic bond coat (BC) and a ceramic top coat (TC), in or
22、der to reduce heat transfer from outside of the top coat through the coating to the substrate Note 1 to entry: See Figure 1. INTERNATIONAL ST ANDARD ISO 18555:2016(E) ISO 2016 All rights reserved 1 ISO 18555:2016(E) Key 1 top coat (TC) 2 bond coat (BC) 3 substrate 4 thermal barrier coating (TBC) Fig
23、ure 1 Diagrammatic view of a section of TBC SOURCE: ISO 14188:2012, definition 3.1, modified 3.2 apparent thermal diffusivity thermal diffusivity of the specimens substrate with bond coat (BC) and substrate with thermal barrier coating (TBC) in a direction normal to the coating surface 3.3 normalize
24、d temperature rise T(t)/T value which is determined by dividing the difference between the temperature of the specimen rear surface after the pulse heating and the temperature of the specimen rear surface before the pulse heating by the difference between the maximum temperature of the specimen rear
25、 surface and the temperature of the specimen rear surface before the pulse heating where T 1 (t) is temperature of specimen rear surface after pulse heating by a flash method; t is time; T 0 is temperature of the specimen rear surface before pulse heating; T max is maximum temperature of specimen re
26、ar surface. Note 1 to entry: See Figure 2.2 ISO 2016 All rights reserved ISO 18555:2016(E) a) Flash method b) Temperature-rise curve under ideal conditions Key 1 pulse heating X time (s) 2 specimen Y normalized temperature rise T(t) / T 3 substrate A areal heat diffusion time (s) 4 TBC 5 front surfa
27、ce 6 rear surface 7 infrared radiometer Figure 2 Flash method and temperature-rise curve under ideal conditions 3.4 temperature-rise curve curve which shows the variation in the normalized temperature rise of the specimen rear surface with time Note 1 to entry: See the thick solid line in Figure 2b.
28、 3.5 half rise-time t 1/2 time required for the normalized temperature rise to reach 0,5 in the temperature-rise curve Note 1 to entry: See Figure 2b. 3.6 areal heat diffusion time A area with time-dimension which is bordered by the horizontal line at the height of the maximum temperature-rise and b
29、y the temperature-rise curve Note 1 to entry: See Figure 2b. 3.7 heat diffusion time 0 time period beginning with pulse heating of the specimen front surface until time at which the specimen temperature becomes uniform d ISO 2016 All rights reserved 3 ISO 18555:2016(E) where 0 is heat diffusion time
30、 (s); d is thickness of specimen (m); is thermal diffusivity (m 2 /s). Note 1 to entry: See Figure 2b. 4 Principle Thermal conductivities of the substrate, BC, and TC are determined according to calculations using the thermal diffusivities, specific heat capacities and bulk densities. The fundamenta
31、l procedures are shown in Figure 3. The fundamental procedures for determining the thermal diffusivities of the substrate, BC, and TC consist of the measurement of temperature-rise curves of three types of specimens (substrate, substrate with BC, and substrate with TBC) by a flash method, and of cal
32、culations. The thermal diffusivities of the BC and TC are obtained by applying a multi-layer analytical model to the temperature-rise curves. The specific heat capacities and bulk densities of the substrate, BC, and TC are measured separately. Figure 3 Fundamental procedures for determining thermal
33、conductivity 5 Apparatus for measuring thermal diffusivity An example of the apparatus for measuring the thermal diffusivity is schematically shown in Figure 4. The apparatus consists of the following. 5.1 Pulse heating light source. 5.2 Data recorder. 5.3 Measurement circuit. 5.4 Infrared radiomete
34、r.4 ISO 2016 All rights reserved ISO 18555:2016(E) 5.5 Specimen holder. 5.6 Chamber. 5.7 Thermocouple. 5.8 Temperature indicator. The apparatus shall be specified according to ISO 18755:2005 and should be calibrated using reference data and reference materials in reference to Annex E in ISO 18755:20
35、05. Key 1 pulse heating light source 7 temperature signal of specimen rear surface 2 data recorder 8 specimen 3 measurement circuit 9 specimen holder 4 infrared radiometer 10 chamber 5 trigger signal 11 thermocouple 6 amplification of signal 12 temperature indicator F i g u r e 4 T y p i c a l a p p
36、 a r a t u s f o r m e a s u r i n g t h e t h e r m a l d i f f u s i v i t y a c c o r d i n g t o a f l a sh m e t h o d 6 Specimen 6.1 Shape and dimensions The shape and dimensions of the specimen shall be as follows. a) The three types of specimens (the substrate, BC and TBC specimens) shall be
37、 used. b) The specimen shape shall be a flat disk (Figure 5) or flat square plate (Figure 6). The diameter or side length of the specimen shall be from 10 10 3m to 15 10 3m. c) The thicknesses of the substrate, BC and TC are given in Table 1. d) The substrate thickness shall be the same for the thre
38、e types of specimens. e) The thickness tolerance of substrate shall be 0,01 10 3m. f) The thickness of BC shall be the same for the BC and TBC specimens. ISO 2016 All rights reserved 5 ISO 18555:2016(E) g) The difference between maximum and minimum thickness shall be 0,01 d for the TBC specimen. h)
39、The coating surface should be polished mechanically in order to smooth the coating surface for the BC and TBC specimens. i) The selections of the shape, the dimension and the thickness shall be decided according to the agreement between parties involved in the transaction. j) For measurement of the
40、specific heat capacities of BC and TC, the coatings stripped off the substrates shall be used as the specimen. a) Substrate specimen b) BC specimen c) TBC specimen Key 1 substrate 2 bond coat 3 top coat D diameter d S thickness of substrate d BC thickness of bond coat d TC thickness of top coat F i
41、g u r e 5 S h a p e o f f l a t d i sk s p e c i m e n s a) Substrate specimen b) BC specimen c) TBC specimen Key 1 substrate 2 bond coat 3 top coat l side length d S thickness of substrate d BC thickness of bond coat d TC thickness of top coat F i g u r e 6 S h a p e o f f l a t s q u a r e p l a t
42、 e s p e c i m e n s6 ISO 2016 All rights reserved ISO 18555:2016(E) T a b l e 1 T h i c k n e s s e s o f s u b s t r a t e , B C , a n d T C Symbol Designation Thickness ( 10 3m) d S thickness of substrate 1,00 d S 2,00 d BC thickness of BC 0,15 d S d BC d TC thickness of TC 0,20 (d S+ d BC ) d TC
43、 d thickness of TBC specimen d = d S+ d BC+ d TC 3,00 6.2 Surface treatment Both surfaces of specimens for measuring thermal diffusivity shall be coated with a thin, opaque, preferably black layer according to ISO 18755:2005. 7 Measuring procedure 7.1 Specimen thicknes s The specimen thickness shall
44、 be measured as follows. a) The specimen thickness shall be measured according to ISO 18755:2005. b) The thickness of BC and TC shall be measured on the image of the coating cross section according to ISO 1463. 7.2 Thermal diffusivity 7.2.1 Measurement of temperature-rise curve According to ISO 1875
45、5:2005, the temperature-rise curve (Figure 2b) shall be measured as follows. a) The specimen shall be placed in the specimen holder of the chamber. The BC and TBC specimens shall be so fixed that their substrate surfaces are heated by pulse light and the temperatures at BC and TC surfaces shall be d
46、etected (See Figure 2a). b) The atmosphere is decided according to the agreement between parties involved in the transaction. c) The temperature of the specimen rear surface before pulse heating, T 0 , shall be measured with the thermocouple. d) With variation of the specimen temperature minimized (
47、0,2 K or less per minute) before pulse heating and with the output of infrared radiometer stabilized; the specimen is subject to pulse heating to measure the temperature rise. 7.2.2 Calculation of thermal diffusivity of substrate The diffusivity of substrate shall be calculated based on the temperat
48、ure-rise curve of the substrate specimen according to ISO 18755:2005. 7.2.3 Calculation of thermal diffusivities of BC and TC The calculation of thermal diffusivities of BC and TC shall be made based on the temperature-rise curve and with application of a multi-layer analytical model. The areal heat
49、 diffusion time method or the theoretical temperature-rise curve method shall be used as the multi-layer analytical model. The model shall be chosen according to the agreement between parties involved in the transaction. ISO 2016 All rights reserved 7 ISO 18555:2016(E) 7.2.3.1 The areal heat diffusion time method (See Annex A) a) Calculation of the areal heat diffusion time across the specimen. The areal heat diffusion time shall b
