1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58characterization of surfaces with surface waves Part 2: Guide to the thickness measurement of coati
2、ngs by photothermic methodThe European Standard EN 15042-2:2006 has the status of a British StandardICS 17.040.20Thickness measurement of coatings and BRITISH STANDARDBS EN15042-2:2006BS EN 15042-2:2006This British Standard was published under the authority of the Standards Policy and Strategy Commi
3、ttee on 31 May 2006 BSI 2006ISBN 0 580 48284 7Cross-referencesThe British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search
4、” facility of the BSI Electronic Catalogue or of British Standards Online.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal oblig
5、ations.Summary of pagesThis document comprises a front cover, an inside front cover, the EN title page, pages 2 to 22, an inside back cover and a back cover.The BSI copyright notice displayed in this document indicates when the document was last issued.Amendments issued since publicationAmd. No. Dat
6、e CommentsA list of organizations represented on this committee can be obtained on request to its secretary. present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related international and Eur
7、opean developments and promulgate them in the UK.National forewordThis British Standard is the official English language version of EN 15042-2:2006. The UK participation in its preparation was entrusted to Technical Committee STI/33, Electrodeposited and related coatings, which has the responsibilit
8、y to: aid enquirers to understand the text;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 thicknessmeasurement of coatings by photothermic metho
9、dMesure 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: Leitfadenzur photothermischen Schichtdicke
10、nmessungThis 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-to-date lists and bibliographical
11、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 the responsibility of a CEN member
12、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, Ireland, Italy, Latvia, Lithuania,
13、 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, 36 B-1050 Brussels 2006 CEN All r
14、ights 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 Foundations of photothermal materials te
15、sting .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”, the secretariat of which is held
16、 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. According to the CEN/CENELEC Internal Re
17、gulations, 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, Lithuania, Luxembourg, Malta, Netherlands,
18、 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 source. The method can be used for
19、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 document. For dated references, only
20、 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 of distributions 3 Terms and definit
21、ions 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 thermal waves depth at which the te
22、mperature 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 periodically 3.4 phase (phase shif
23、t) 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 into heat NOTE In most technical ap
24、plications 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 about 1/e or 37 % NOTE 1 1/e, with nat
25、ural 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 characterizing heat propagation in a body with
26、 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 body (or medium) with time-dependen
27、t 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 Rlsthermal parameter that is a degree
28、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 Description See Equation T(x,t) K amplitude
29、 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 effusivity 5 m2/s thermal diffusivity
30、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 below the boundary interface t s tim
31、e 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 thermal wave the term “temperature w
32、ave“ 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 limiting case pulsed. The physical
33、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. EN 15042-2:2006 (E) 7 An example of
34、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 year penetrating up to several met
35、ers 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 physical variables and parameters that are
36、 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, if the heated surface is taken to
37、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 frequency f of the heating. The ampl
38、itude 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 the equation: ()ck = (6) According
39、ly, 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. The amplitude of the thermal wave m
40、easurable 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 one hand by the ratio of the thermal
41、 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. Given a known value of the therma
42、l 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 thermal waves (see Clause 6). 5.1.2
43、 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-dependent heating of a surface: () teFtx
44、T02,0 = (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 thermal properties. An example is the
45、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 one another. The thermal diffusivi
46、ty (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 the heat capacity per unit volume can
47、 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, surface roughness and anisotropy on the
48、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 heating, a depth-resolved measurem
49、ent 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 measurement In principle, thermal waves can be used to measure any physical variable that affects the heat transfer and temperature distributio
