1、 DEUTSCHE NORMJune 2006DIN EN 15042-2 ICS 17.040.20 Supersedes DIN 50992-2:2002-05 Thickness measurement of coatings and characterization of surfaces with surface waves Part 2: Guide to the thickness measurement of coatings by photothermic method English version of DIN EN 15042-2:2006-06 Schichtdick
2、enmessung und Charakterisierung von Oberflchen mittels Oberflchenwellen Teil 2: Leitfaden zur photothermischen Schichtdickenmessung Englische Fassung DIN EN 15042-2:2006-06 Document comprises 24 pages No part of this standard may be reproduced without prior permission of DIN Deutsches Institut fr No
3、rmung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany, has the exclusive right of sale for German Standards (DIN-Normen). English price group 12 www.din.de www.beuth.de !,o-W“10.06 9761052DIN EN 15042-2:2006-06 2 National foreword This standard has been prepared by CEN/TC 262 Metallic and ot
4、her inorganic coatings (Secretariat: United Kingdom). The responsible German body involved in its preparation was the Normenausschuss Materialprfung (Materials Testing Standards Committee), Technical Committee NMP 161 Mess- und Prfverfahren fr metallische und andere anorganische berzge. Amendments T
5、his standard differs from DIN 50992-2:2002-05 as follows: a) DIN 50992-2:2002-05 has been taken over as a European Standard without any modifications. b) A bibliography has been included. Previous editions DIN 50992-2: 2002-05 National Annex NA (informative) Bibliography DIN EN ISO 11145, Optics and
6、 optical instruments Laser and laser-related equipment Vocabulary and symbols EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 15042-2April 2006ICS 17.040.20English VersionThickness measurement of coatings and characterization ofsurfaces with surface waves - Part 2: Guide to the thicknessmeasuremen
7、t of coatings by photothermic methodMesure de lpaisseur des revtements et caractrisationdes surfaces laide dondes de surface - Partie 2 : Guidepour le mesurage photothermique de lpaisseur desrevtementsSchichtdickenmessung und Charakterisierung vonOberflchen mittels Oberflchenwellen - Teil 2: Leitfad
8、enzur photothermischen SchichtdickenmessungThis European Standard was approved by CEN on 2 March 2006.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up
9、-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder
10、the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland,
11、 Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart
12、, 36 B-1050 Brussels 2006 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 15042-2:2006: EEN 15042-2:2006 (E) 2 Contents Page Foreword3 1 Scope 4 2 Normative references 4 3 Terms and definitions .4 4 Symbols and abbreviation 6 5 Found
13、ations of photothermal materials testing .6 6 Photothermal measuring methods 12 7 Applications in layer thickness measurements .17 Bibliography 22 EN 15042-2:2006 (E) 3 Foreword This document (EN 15042-2:2006) has been prepared by Technical Committee CEN/TC 262 “Metallic and other inorganic coatings
14、”, the secretariat of which is held by BSI. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by October 2006, and conflicting national standards shall be withdrawn at the latest by October 2006. Accor
15、ding to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuan
16、ia, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 15042-2:2006 (E) 4 1 Scope This document describes methods for the measurement of the thickness of coatings by means of thermal waves generated by a radiation
17、source. The method can be used for coatings whose thermal properties (e.g. thermal conductivity) are different from those of the substrates in a range from a few microns to some hundred microns. 2 Normative references The following referenced documents are indispensable for the application of this d
18、ocument. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO/DGuide 99998, Guide to the expression of uncertainty in measurement (GUM) Supplement 1: Numerical methods for the propagation o
19、f distributions 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 amplitude of the thermal wave T0maximum local temperature variation of the oscillating part for periodic-harmonic heating processes NOTE See Equation 2. 3.2 penetration depth of
20、thermal waves depth at which the temperature variation below a modulated heated surface is still measurable. NOTE In general, the penetration depth is of the order of magnitude of the thermal diffusion length 3.3 modulation frequency f frequency at which the intensity of the heating radiation varies
21、 periodically 3.4 phase (phase shift) of the thermal wave measure of the temporal delay of the temperature oscillation relative to the excitation for periodic-harmonic heating processes NOTE See Equation 3. 3.5 photothermal efficiency proportion of the incident radiation intensity that is converted
22、into heat NOTE In most technical applications it is approximately identical to the absorption. EN 15042-2:2006 (E) 5 3.6 thermal diffusion length characteristic length of the thermal diffusion with pulsed heating or periodically modulated heating, where the temperature amplitude has decreased to abo
23、ut 1/e or 37 % NOTE 1 1/e, with natural number e = 2,71828. NOTE 2 See Equation 4. 3.7 thermal diffusion time characteristic time that a thermal wave or a temperature pulse requires for penetrating a layer of finite thickness NOTE See Equation 7. 3.8 thermal diffusivity thermal parameter characteriz
24、ing heat propagation in a body with time-dependent heating NOTE See Equation 6. 3.9 thermal effusivity e thermal parameter determining the surface temperature of a body with time-dependent heating NOTE See Equation 5. 3.10 thermal wave spatiotemporally variable temperature field that is set up in a
25、body (or medium) with time-dependent heating and is described by the heat conduction equation NOTE 1 see Equation 1. NOTE 2 The thermal wave is generated in one limiting case by a periodic-harmonic excitation, in the other limiting case by a pulsed excitation. 3.11 thermal reflection coefficient Rls
26、thermal parameter that is a degree of the reflection of the thermal wave at the boundary interface between two layers of different effusivity and thus describes the heat transfer across this boundary interface NOTE See Equation 8. EN 15042-2:2006 (E) 6 4 Symbols and abbreviation Symbol Unit Descript
27、ion See Equation T(x,t) K amplitude of the temperature oscillation of the thermal wave 1 T0(x) K amplitude of the temperature oscillation of the thermal wave at the surface (x = 0) 2 rad phase of the temperature oscillation of the thermal wave 3 m thermal diffusion length 4 e Ws1/2/(m2K) thermal eff
28、usivity 5 m2/s thermal diffusivity 6 s thermal diffusion time 7 F0W/m2heat flow/excitation power density 7 photothermal efficiency k W/(mK) thermal conductivity 12 Kg/m3mass density 13 c J/(kgK) specific heat capacity 13 f s-1modulation frequency i0W/m2incident radiant power density 2 x m location b
29、elow the boundary interface t s time 5 Foundations of photothermal materials testing 5.1 Physical foundations 5.1.1 Thermal waves The concept “thermal wave(s)“ describes a spatially and temporally variable temperature field that is generated in a body by time-dependent heating. Besides the concept t
30、hermal wave the term “temperature wave“ is also used in technical literature. The excitation of the spatiotemporally variable temperature field mathematically described by a diffusion equation - the heat conduction equation - can occur in the one limiting case periodic-harmonically and in the other
31、limiting case pulsed. The physical foundations 1, 5, 6, 7 can be derived both for the harmonic excitation and for the pulsed excitation, and are related by a Fourier transformation. This clause considers primarily the harmonic excitation; the derivation for the pulsed excitation can be found in 8. E
32、N 15042-2:2006 (E) 7 An example of thermal waves observable in nature is the temperature distribution in the ground. This distribution is dependent on the time of day and year, with the daily variation in temperature reaching a penetration depth of nearly 30 cm and the variation in the course of the
33、 year penetrating up to several meters 9. The example of thermal waves 10 excited by the harmonic-periodic and large-area irradiation of homogeneous, semi-infinite bodies absorbing only at the surface, can be used to describe the most important properties of thermal waves and to identify the physica
34、l variables and parameters that are measurable by means of thermal waves during materials testing. ( ) () ()()xftxTtxT += 20cos, (1) NOTE Terms are defined in Clause 4. () ()/exp200xfeixT = (2) ()4 =xx (3) f = (4) The amplitude of the thermal wave (Equation 1) decreases exponentially with the depth,
35、 if the heated surface is taken to be x = 0. The measurable penetration depth has the order of magnitude of the thermal diffusion length . Conditioned by the frequency-dependency of the thermal diffusion length (Equation 4), the penetration depth can be adjusted by precisely varying the modulation f
36、requency f of the heating. The amplitude of the thermal wave T0(x) (Equation 2) and the phase shift (x) (Equation 3) depend on the following thermal properties: The thermal effusivity (thermal penetration coefficient), e, is given by the equation: cke = (5) and the thermal diffusivity, , is given by
37、 the equation: ()ck = (6) Accordingly, frequency-dependent measurements of the amplitude and phase of the thermal wave provide depth-resolved information on these combined thermal parameters. In Equations (5) and (6), k is the thermal conductivity, the mass density and c the specific heat capacity.
38、The amplitude of the thermal wave measurable at the surface is proportional to the photothermal efficiency , which specifies the proportion of the incident radiant power converted into heat. With layered systems the amplitude and the phase shift of the temperature oscillation are determined on the o
39、ne hand by the ratio of the thermal effusivity of layer and substrate elayer/esubstrate, and on the other hand by the thermal diffusion time for the layer: layerlayerlayerl2= (7) EN 15042-2:2006 (E) 8 where llayeris the geometrical thickness of the layer; layeris the thermal diffusivity of the layer
40、. Given a known value of the thermal diffusivity of the layer and a sufficiently large thermal contrast, describable according to 11 by the thermal reflection coefficient: substratelayersubstratelayerlseeeeR+= (8) contactless and non-destructive layer thickness determination is possible by means of
41、thermal waves (see Clause 6). 5.1.2 Thermal Properties The significance of the thermal effusivity and the thermal diffusivity can be made especially clear by means of special time-dependent heating (step function). According to 12, the thermal effusivity e (Equation 5) is a measure of the time-depen
42、dent heating of a surface: () teFtxT02,0 = (9) where F0is the constant heat flow absorbed at the surface and T(x = 0,t) represents the heating of the surface at time t after the start of heating. The thermal effusivity determines the contact temperature between bodies and layers having different the
43、rmal properties. An example is the contact temperature: ()()212211eeTeTeTcontact+= (10) occurring at the boundary interface between two semi-infinite bodies having different thermal effusivity e1and e2and different initial temperatures T1and T2, after these bodies have been brought into contact with
44、 one another. The thermal diffusivity (Equation 6) is a measure of the propagation of the temperature through a homogenous body: () ()= =txtxTtttxeFtxT 4,0/4exp,020ierfcd (11) Given measurements of the thermal effusivity and thermal diffusivity by means of thermal waves, the heat conductivity and th
45、e heat capacity per unit volume can be determined using Equations (5) and (6): ek = (12) ()ec = (13) EN 15042-2:2006 (E) 9 Here it shall be kept in mind that with Equations (12) and (13) effective parameters shall be determined for the actual test object that include the influence of porosity, surfa
46、ce roughness and anisotropy on the heat transfer 13. 5.1.3 Thermal depth profiling The thermal diffusion length (Equation 4) is a measure of the penetration depth of the thermal wave. Since the thermal diffusion length and hence the penetration depth can be varied via the modulation frequency of the
47、 heating, a depth-resolved measurement of thermal properties is possible. The resolution limits basically depend on the thermal contrast of the individual layers, on the detection procedure used and on the technical quality of the detectors. 5.1.4 Measurable variables and possibilities of measuremen
48、t In principle, thermal waves can be used to measure any physical variable that affects the heat transfer and temperature distribution in a body, i.e. the spatial distribution of the thermal effusivity and of the thermal diffusivity or the layer thickness in layered systems with different thermal pr
49、operties. Accordingly, it is possible to measure directly or infer other characteristic data, such as the hardness of metallic materials, porosity and moisture in solid bodies, if these variables affect heat transfer properties. In these cases, however, the correlation of, for example, the porosity, moisture 13, 14 or hardness 15 with the effective thermal properties shall be determined through calibration. Optical
