1、DEUTSCHE NORM Januarv 1995 DIN Metallic coatings Measurement of coating thickness with the scanning electron Enalish version of DIN EN IS0 9220 EN IS0 922 microscope method (IS0 9220 : 1988) This standard incorporates the English version of Is0 9220. ICs 25.220.40 Descriptors: Metal coatings, coatin
2、g thickness, measurement, scanning electron microscopy. Metallische berzge: Messung der SChichtdiCke; Verfahren mit Rasterelektronenmikroskop (IS0 9220 : 1988) European Standard EN IS0 9220:1994 has the status of a DIN Standard. A comma is used as the decimal marker. National foreword This standard
3、has been published in accordance with a decision taken by CEN/TC 262 to adopt, without alteration, International Standard IS0 9220 as a European Standard. The responsible German body involved in its preparation was Technical Committee berzge und Korrosion of the Normenausschu Materialprfung (Materia
4、ls Testing Standards Committee). The DIN Standards corresponding to the International Standards referred to in clause 2 are as follows: IS0 1463 IS0 2064 DIN EN IS0 1463 DIN EN IS0 2064 International Patent Classification G O1 B 007/06 EN comprises 7 pages. fth Verlag GmbH. Berlin. has the exclusive
5、 right of sale for German Standards (DIN-Normen). DIN EN IS0 9220 End. Price arow 08.95 - -, Sales No. i 107 EUROPEAN STANDARD NORME EUROPENNE EUROPAISCHE NORM EN IS0 9220 October 1994 ICs 25.220.40 Descriptors: Metal coatings, coating thickness, measurement, scanning electron microscopy. English ve
6、rsion Metallic coatings Measurement of coating thickness Scanning electron microscope method (IS0 9220: 1988) Revtements mtalliques; mesurage de lpaisseur de revtement; mthode au microscope lectronique balayage (IS0 9220 : 1988) Metallische berzge; Messung der Schichtdicke; Verfahren mit Raster- ele
7、ktronenrnikroskop (IS0 9220: 1988) This European Standard was approved by CEN on 1994-10-26 and is identical to the IS0 Standard as referred to. CEN members are bound to comply with the CENKENELEC Intemal Regulations which stipu- late the conditions for giving this European Standard the status of a
8、national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards 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 i
9、n any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece,
10、Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassar 36, B-1050 Brussels O 1994. Copyright reserv
11、ed to all CEN members. Ref. No. EN IS0 9220: 1994 E Page 2 EN IS0 9220 : 1994 Foreword International Standard IS0 9220 : 1988 Metallic coatings; measurement of coating thickness; scanning electron microscope method which was prepared by ISO/TC 107 Metallic and other inorganic coatings of the Interna
12、tional Organization for Standardi- zation, has been adopted by Technical Committee CEN/TC 262 Protection of metallic materials against corrosion as a European Standard. CEN/TC 262 had decided to submit IS0 9220 : 1988 for Formal Vote. The result was positive. This European Standard shall be given th
13、e status of a national standard, either by publication of an identical text or by endorsement, and conflicting national standards withdrawn, by April 1995 at the latest. In accordance with the CENICENELEC Internal Regulations, the following countries are bound to implement this European Standard: Au
14、stria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. Endorsement notice The text of the International Standard IS0 9220:1988 was approved by CEN as a European Standard without any
15、 modifica- tion. NOTE: Normative references to international publications are listed in Annex ZA (normative). 1 Scope Page 3 EN IS0 9220: 1994 5 Instrumentation This International Standard specifies a method for the measurement of the local thickness of metallic coatings by examination of cross-sect
16、ions with a scanning electron micro- scope (SEM). It is destructive and has an uncertainty of less than 10 % or 0,l pm, whichever is greater. It can be used for thicknesses up to several millimetres, but it is usually more practical to use a light microscope (IS0 1463) when applicable. 2 Normative r
17、eferences The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this Internationa
18、l Standard areencouraged to investigate the possibility of applying the most recent editions of the standards listed below. Members of IEC and IS0 maintain registers of currently valid International Standards. IS0 1463 : 1982, Metallic and oxide coatings - Messurement of coating thickness - Microsco
19、pical method. IS0 2064 : 1980, Metallic and other non-organic coetings - Definitions and conventions concerning the measurement of thickness. 3 Definition For the purposes of this International Standard, the following definition applies. local thickness: The mean of the thickness measurements, of wh
20、ich a specified number is made within a reference area. (See IS0 2064.) 4 Principle A test specimen is cut, ground, and polished from a cross- section of the coating for metallographic examination by a scanning electron microscope. The measurement is made on a conventional micrograph or on a photogr
21、aph of the video waveform signal for a single scan across the coating. 5.1 Scanning electron microscope (SEM) The SEM shall have a resolution capability of 50 nm or better. Suitable instruments are available commercially. 5.2 SEM stage micrometer A stage micrometer or graticule is required for calib
22、ration of the magnification of the SEM. The stage micrometer or graticule shall have an uncertainty of less than 5 % for the magnification employed. Suitable stage micrometers or graticules are available commercially. 6 Factors influencing the measurement results The following factors may affect the
23、 accuracy of a measure- ment of coating thickness. 6.1 Surface roughness If the coating or its substrate is rough relative to the coating thickness, one or both of the interfaces bounding the coating cross-section may be too irregular to permit accurate measure- ment of the average thickness in the
24、field of view. 6.2 Taper of cross-section If the plane of the cross-section is not perpendicular to the plane of the coating, the measured thickness will be greater than the true thickness. For example, an inclination of loo to the perpendicular will contribute a 1.5 % error. 6.3 Specimen tilt Any t
25、ilt of the specimen (plane of cross-section) with respect to the SEM beam may result in an inaccurate measurement. NOTE - If the tilt of the test specimen is different from that used for calibration, inaccuracies may result. 6.4 Coating deformation Detrimental deformation of the coating can be cause
26、d by excessive temperature or pressure during the mounting and preparation of cross-sections of soft coatings or coatings that melt at low temperatures, and by excessive abrasion of brittle materials during preparation of cross-sections. Page 4 EN IS0 9220 : 1994 6.5 Rounding of edges of the coating
27、 If the edge of the coating cross-section is rounded, .e. if the coating cross-section is not completely flat up to its edges, the ObSenred thickness may differ from the true thickness. Edge rounding can be caused by improper mounting, grinding, polishing, or etching (see 6.6 and clause A.1). 6.6 Ov
28、erplating Overplating of the test specimen serves to protect the coating edges during preparation of cross-sections and thus to prevent an inaccurate measurement. Removal of the coating material during surface preparation for overplating can cause a low thickness measurement. 6.7 Etching Optimum etc
29、hing will produce a clearly defined and narrow dark line at the interface between the two metals. A wide or poorly defined line can result in an inaccurate meaurement. 6.8 Smearing Polishing may leave smeared metal that obscures the true boundary between two metals and results in an inaccurate measu
30、rement. This may occur with soft metals like lead, indium, and gold. To help identify whether or not there is smearing, repeat the polishing, etching, and measurement several times. Any significant variation in readings is an indica- tion of possible smearing. 6.9 Poor contrast The visual contrast b
31、etween metais in an SEM is poor when their atomic numbers are close together. For example, bright and semi-bright nickel layers may not be discriminable unless their common boundary can be brought out sufficiently by appropriate etching and SEM techniques. For some metal com- binations, energy dispe
32、rsive X-ray techniques (see A.3.5) or backscatter images (see A.3.6) can be helpful. 6.10 Magnification For a given coating thickness, measurement errors tend to increase with decreasing magnification. If practical, the magnification should be chosen so that the field of view is between 1,5 and 3 ti
33、mes the coating thickness. The magnification readout of an SEM often differs from the actual magnification by more than the 5 % often quoted and, for some instruments, the magnification has been found to vary by 25 % across the field. Magnification errors are minimized by appropriate use of an SEM s
34、tage micrometer. 6.11 Uniformity of magnification Because the magnification may not be uniform over the entire field, errors can occur if both the calibration and the masure- ment are not made over the same portion of the field. These errors can be very significant. 6.12 Stability of magnification 6
35、.12.1 The magnification of an SEM may drift with time. This effect is minimized by mounting the stage micrometer and test specimen side by side on the SEM stage so as to keep the transfer time short. 6.12.2 A change in magnification can occur when adjustments are made with the focusing and other SEM
36、 dec- tronic controls: for example the scan rotation, operating voltage and contrast controls. Such a change is prevented by not using the focus controls or other SEM electronic controls after photographing the stage micrometer scale except to focus using the x, y and z controls of the stage. Approp
37、riate manipulation of the x, y and z controls will bring the specimen surface to the focal point of the SEM beam. 6.13 Stability of micrographs Dimensional changes of micrographs can take piace with time and with temperature and humidity changes. If the calibration micrograph of the stage micrometer
38、 scale and the micrograph of the test specimen are kept together and time is allowed for stabilization of the photographic paper, errors from this source will be minimized. The use of resin-coated paper is advised. 7 Preparation of cross-sections Prepare the test specimen so that a) the cross-sectio
39、n is perpendicular to the plane of the coating; b) the surface is flat and the entire width of the coating image is simultaneously in focus at the magnification to be used for the measurement; c) all material deformed by cutting or cross-sectioning is removed; di the boundaries of the coating cross-
40、section are sharply defined by no more than contrasting appearance, or by a narrow, well-defined line; e) if the video waveform signal is to be measured, the signal trace is flat except across the two boundaries of the coating. NOTE - Further guidance is given in annex A. 8 Calibration of instrument
41、s 8.1 General Before use, each instrument (5.1) shall be calibrated with an SEM stage micrometer or graticule (5.2) using a photograph taken under the same conditions as used for the sample measurement. Appropriate attention shall be given to the factors listed in clause 6, to the procedures specifi
42、ed in clause 9, and to the un- certainty limits of clause 10. The stability of the calibration shall be checked at frequent intervals. Page 5 EN IS0 9220: 1994 8.2 Photography Photograph the image of the micrometer scale using a minimum signal-to-noise ratio of 2 to f and with sufficient image contr
43、ast for later measurement. 8.3 Measurement 8.3.1 Measure the perpendicular centre-to-centre distance between the lines in the photographed image to the nearest 0,l mm. Use a diffraction plate reader or equivalent for this measurement. 8.3.2 Repeat the measurement at at least three different location
44、s at least 3 rnm apart on the photograph to determine the average spacing. 8.4 Calculation of magnification Calculate the magnification of the photograph by dividing the average of the measurements between selected lines by the certified distance between the iines: where y is the magnification; I, i
45、s the measured distance, in millimetres, on the photograph (average of measurements): I, is the certified distance, in micrometres. 9 Procedure 9.1 Each instrument (5.1) shall be operated in accordance with the manufacturers instructions. Appropriate attention shall be given to the factors listed in
46、 clause 6 and to the uncer- tainty requirements of clause 10. 9.2 Make a micrograph of the test specimen under the same conditions and instrument settings as used for the calibration and make an appropriate measurement of the micrograph image. Carry out this step in accordance with 9.2.1 or 9.2.2. 9
47、.2.1 Conventional micrograph 9.2.1.1 With the boundaries of the coatings clearly and sharply defined, make conventional micrographs of the SEM stage micrometer scale and of the test specimen. 9.2.1.2 Measure the micrographs to at least the nearest O, 1 mm using a diffraction plate reader or other op
48、tical device for making accurate linear measurements on film or paper. If this is not practical, the sample preparation may not have been suitable. 9.2.2 Video waveform signal 9.2.2.1 Photograph the video waveform signal for a signal scan across the coating cross-section and across the SEM stage mic
49、rometer scale. 9.2.2.2 To measure the coating, measure the horizontal distance between the inflection point of the vertical portions of the scan at the boundaries of the coatings. Make the measurements to the nearest 0.1 mm using a diffraction plate reader or equivalent device. NOTE - Further guidance is given in annex A. 9.3 Calculate the thickness from the equation d=-x1000 lm Y where d is the coating thickness, in micrometres; 1, is the linear distance, in millimetres, on the micrograph; y is the magnification factor (see 8.4). 10 Measurement uncertainty The in
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