1、A .- CEN EN*IS0*9220 94 3404589 OLLLL88 258 I BRITISH STANDARD Metallic coatings - Measurement of coating thickness - Scanning electron microscope method The European Standard EN Is0 9220 : 1994 has the status of a British Standard BS EN IS0 9220 : 1995 CEN EN*ISO*9220 94 3404589 01L1189 194 BS 541
2、1 : Part 16 : 1989 Contents National foreword Committees responsible r Page Inside front cover Back cover Method 1 scope 2 Normative references 3 Definition 4 Principle 5 Instrumentation 6 Factors influencing the measurement results 7 Preparation of cross-sections 8 Calibration of instruments 9 Proc
3、edure 10 Measurement uncertainty 11 Expression of results 12 Test report Annex A General guidance on the preparation and measurement of cross-sections page 2 2 3 3 3 4 National foreword This Part of BS 541 1 has been prepared under the direction of the Surface Coatings (other than Paints) Standards
4、Policy Committee. It is identical with IS0 9220: 1988 Metallic coatings - Measurement of coating thickness - Scanning electron microscope method, which was prepared by Technical Committee 107, Metallic and other non-organic coatings, of the International Organization for Standardization (ISO), with
5、the active participation and approval of the UK. in 1994 the European Chnnth for standardization (CEN) acceed iS922: 1989 as Eurapean standard EN Is0922: 1994. Asa coxtsequence ofinplementing the Emopean Standard this British !hndd is mtunbemd as BSENEc09220 and any reference to ES 5411 : Part 16 sh
6、ould 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. Appropriate manipulation
7、 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 place with time and with temperature and humidity changes. If the calibration micrograph of the stage micrometer scale and the mic
8、rograph 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 ai the cross-section is perpendicular
9、 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-section are sharpl
10、y 4 defined by no more than contrasting appearance, or by a narrow, well-defined line; el 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 instruments 8.1 General Be
11、fore 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 specified in clause 9,
12、and to the un- certainty limits of clause 10. The stability of the calibration shall be checked at frequent intervals. 2 3404589 Olilll9Y 551 .- 2 CEN EN*ISO*9220 94 IS0 9220 : 1988 (E) 8.2 Photography Photograph the image of the micrometer scale using a minimum signal-to-noise ratio of 2 to 1 and w
13、ith sufficient image contrast 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 leas
14、t three dierent locations at least 3 mm apart on the photograph to 1, is 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 ins
15、tructions. Appropriate attention shall be given to the factors listed in 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 mi
16、crograph image. Carry out this step in accordance with 9.2.1 or 9.2.2. 9.2.1 Conventional micrograph 9.2.1.1 With the boundaries of the, coatings ciearly 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
17、at least the nearest 0,l mm using a diffraction plate reader or other optical device for making accurate linear measurements on film or paper. If this is not practical, the sample preparation may not haue been suitable. 9.2.2 Video waveform signal 9.2.2.1 Photograph the video waveform signal for a s
18、ignal scan across the coating cross-section and across the SEM stage micrometer 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 usin
19、g a diffraction plate reader or equivalent device. NOTE - Further guidance is given in annex A. 9.3 Calculate the thickness from the equation d=-x000 Y where d is the coating thickness, in micrometres; I, is the linear distance, in millimetres, on the micrograph; y is the magnification factor (see 8
20、.4). 10 Measurement uncertainty The instrument, its calibration. and its operation shall be such that the uncertainty of the coating thickness measurements is less than 10 % or 0,l pm, whichever is greater (see A.3.7). 11 Expression of results Express the results in micrometres to the nearest 0.01 p
21、m, but with three digits if greater than 1 pm. NOTE - This requirement is intended to minimize measurement uncertainty due to rounding of calculated values. 12 Test report The test report shall contain at least the following information : a) reference to this International Standard; b) the measured
22、value; c identification of the test specimen(s); d) location of the measurements on the test specimens) ; e) the magnification as measured before and after the test specimen measurements; f) any unusual features of the measurements that may have affected the results; g) date the measurements were ma
23、de; h) name of the individual responsible for the measure- ments; i) type of measurements: conventional micrograph or video waveform signal. 3 CEN EN%ISO*9220 94 3404589 0111195 498 Annex A (informative) General guidance on the preparation and measurement of cross-sections A.0 Introduction A.2.2 A c
24、onvenient way to check for tapering of the cross- section is to mount a small diameter rod or wire with the The preparation of specimens and measurements of coating Specimen SO that the perpendicular cross-cection of the rod is thickness are greatly dependent on individual techniques and parallel to
25、 that Of the coating. If a taper is present, the Cros- there is a variety of suitable techniques available. It is not section of the rod will be elliptical. reasonable to specify only one set of techniques, and it is A.l Mounting overpolishing does not selectively remove one of the metals more than
26、the other CO that the signal scan is distorted. With careful polishing i is unnecessary to use chemical etches. To prevent rounding of the edges of the coating cross-section, the free surface of the coating should be supported so that there is no space between the coating and its support. This is A.
27、3 Use of the scanning electron microscope parent width of the coating cross-section can vary depending on the contrast and brightness settings. The can be as great as 10 % without any change in instrument magnification. To minimize the resulting uncertainty, adjust the contrast and bightness so that
28、 the image shows detail of the The surface of the mounting material has to be made electri- ally conducting to prevent a charge build-up. If very soft materials are being prepared, abrasive particles may totally immersing abrasive papers in a lubricant during grinding i become embedded during grindi
29、ng. This my be minimized by materials on either side of each boundary. or by using a copious flow of lubricant. If abrasive particles do become embedded, they may be removed by applying a short, light hand polish with metal polish after grinding and before diamond finishing or by one or more cyclec
30、of alternate etching and polishing. A.3.2 Because the magnification of an SEM can change spontaneously with time and can change as a result of changing other instrument settings, it is advisable to calibrate the instrument immediately before or after measurement of the test specimen. For critical me
31、asurements, the average of , calibration measurements made before and after measurement of the specimen should be used. This ensures that MI change in the magnification has occurred and provides information on the precision of the calibration. A.2 Grinding and polishing A.2.1 It is essential to keep
32、 the cross-section surface of the mount perpendicular to the coating. This is facilitated by incor- porating additional pieces of a similar metal in the plastic mounting near the outer edges, by periodically changing the direction of grinding (rotating through Wo), and by keeping the grinding time a
33、nd pressure to a minimum. If, before grinding, reference marks are inscribed on the sides of the mounts, any inclination from the horizontal is easily measured. Grind the mounted specimens on suitable abrasive paper, using an acceptable lubricant such as water or white spirit, and apply minimum pres
34、sure to avoid bevelling the surface. Initial grind- ing should employ 100 or 180 grade abrasive to reveal the true specimen profile and to remove any deformed metal. Subse- A.3.3 If the video waveform trace is measured, the measure- ment is made of the horizontal distance between the inflection poin
35、ts at the boundaries. The inflection point is halfway between the horizontal traces of the two materials. Because this horizontal distance is independent of the contrast and brightness settings and is precisely defined, some operators prefer to measure the video waveform trace for accurate measureme
36、nts at higher magnifications. A.3.4 polished specimen that yields a flat, smooth signal. For a video waveform trace, select a portion of the quently, use grades 240, 320, 500 and 600 without exceeding grinding times of 30 to 40 s on each paper; alter the direction of grinding by Wo for each change o
37、f paper. Then polishing successively with 6 to 9 pm, 1 pm, and 0.5 pm diamond on microcloth is often recommended. A.3.5 Many SEMS are equipped with energy dispercive X-ray spectroscopy (EDS) which can be helpful in dwng the metal coating layers. At best the resolution of EDS ic about 1 wm and is oft
38、en poorer. . . . A.3.6 The use of backscatter images instead of secondary electron images can also be helpful in distinguishing metal layers with atomic numbers as close together as 1, and with a resolution of 0.1 pm. A.3.7 A comprehensive investigation of measurement errors has not been reported. F
39、or a thin gold coating, one laboraton/ reported a measurement uncertainty of 0,039 pm for the cer- tification of the SEM stage micrometer scale, 0.02 urn for the measurement of the calibration micrographs, and 0,02 pm for the measurement of the video waveform signal scan. Publications referred to Se
40、e national foreword CEN EN#IS0*7220 94 3404.589 OLLLL97 260 f Page 3 EN IS0 9220 : 1994 Annex ZA (normative) Normative references to international publications with their relevant European publications This European Standard incorporates by dated or undated reference, provisions hm other publication
41、s. These normative references are cited at the appropriate piaces in the text and the publications are listed hemafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revisim For un
42、dated references the latest edition of the publication refened to applies (including amenments). Publication Year tie ENIEID Yeu Is0 1463 Metauic and oxide coatings - Mtzwum of coating Is0 2064 Meiaic and other rwninyanic coatings - Dnitions and EN Is0 1463 EN IS0 2064 thickness-MiCn3Smelhod co122en
43、tiO12s concem2ng the wleasurt?m%nl of th- P Amd. No. This British Standard, having been prepared under the direction of the Surface Coatings (other than Paints) Standards Policy Committee, was published under the authority of the Board of BSI and comes into effect on 29 SWtember 1989 B British Stand
44、ards Institution, 1989 ISBN O 580 17640 1 The following BSI references relate to the work on this standard: Committee reference SRCI14 Draft for comment 87/53727 DC British Standards Institution. Incorporated by Royal Charter, BSI is the independent national body for the preparation of British Stand
45、ards. It is the UK member of the International Organization for Standardization and UK sponsor of the British National Committee of the International Electrotechnical Commission. In addition to the preparation and promulgation of standards, ES1 offers specialist services including the provision of i
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47、 in all BSI publications. No part of this publication may be reproduced in any form without the prior permission in writing of BSI. This does not preclude the free use, in the course of MA o _ Date of issue BS5411 :Part16:1989 IS0 9220 : 1988 implementing the standard, of necessary details such as s
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