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1、Reference number ISO 3613:2000(E) ISO 2000 INTERNATIONAL STANDARD ISO 3613 Second edition 2000-06-15 Chromate conversion coatings on zinc, cadmium, aluminium-zinc alloys and zinc-aluminium alloys Test methods Couches de conversion au chromate sur zinc, cadmium et alliages daluminium-zinc et de zinc-
2、aluminium Mthodes dessai ISO 3613:2000(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performi
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5、etariat at the address given below. ISO 2000 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the ad
6、dress below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 ? CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.ch Web www.iso.ch Printed in Switzerland ii ISO 2000 All rights reserved ISO 3613:2000(E) ISO 2000 All rights res
7、ervediii 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 through ISO technical committees. Each member body interested in a subject for
8、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 collaborates closely with the International Electrotechnical Commission (IEC) on al
9、l matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International S
10、tandard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Interna
11、tional Standard ISO 3613 was prepared by Technical Committee ISO/TC 107, Metallic and other inorganic coatings, Subcommittee SC 2, Methods of inspection and coordination of test methods. This second edition cancels and replaces the first edition (ISO 3613:1980), which has been technically revised. -
12、,-,- INTERNATIONAL STANDARDISO 3613:2000(E) ISO 2000 All rights reserved1 Chromate conversion coatings on zinc, cadmium, aluminium-zinc alloys and zinc-aluminium alloys Test methods WARNING This International Standard calls for the use of substances and/or procedures that can be injurious to health
13、if adequate precautions are not taken. It refers only to technical suitability and in no way absolves either the designer, the producer, the supplier or the user from statutory and all other legal obligations relating to health and safety at any stage of manufacture or use. 1Scope This International
14、 Standard specifies methods for the determination of the ?presence of colourless1)chromate conversion coatings; ?presence and quantity of hexavalent chromium in colourless and coloured coatings on zinc, cadmium, aluminium (55 % mass fraction)-zinc and zinc-aluminium (5 % mass fraction) alloys; ?tota
15、l chromium content per unit area on zinc and cadmium; ?mass per unit area of both colourless and coloured coatings; ?satisfactory adhesion of chromate conversion coatings; ?quality of chromate coating. These methods are applicable ?to colourless and coloured chromate conversion coatings containing t
16、ri- and hexavalent chromium in varying proportions and produced by either chemical or electrochemical processes; ?only to chromate coatings that are free from any supplementary coatings such as oil, water or solvent-based polymers or wax. 1)The application of very thin, colourless, practically invis
17、ible chromate conversion coatings is frequently called “passivation“, while the application of thicker, coloured chromate conversion coatings is often called “chromating“. The term passivation is not correct and is, therefore, not recommended. ISO 3613:2000(E) 2 ISO 2000 All rights reserved 2Normati
18、ve references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements base
19、d on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of curre
20、ntly valid International Standards. ISO 3892:2000, Conversion coatings on metallic materials Determination of coating mass per unit area Gravimetric methods. ISO 4520:1981, Chromate conversion coatings on electroplated zinc and cadmium coatings. ISO 9227:1990, Corrosion tests in artificial atmospher
21、es Salt spray tests. IEC 60068-2-30:1980, Environmental testing Part 2: Tests. Test Db and guidance: Damp heat, cyclic (12 + 12 hour cycle). 3Reagents During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity
22、. 3.1Test solution A (see 5.2). Dissolve 1 mg of diphenylcarbazide in a mixture of 60 ml glacial acetic acid and 40 ml distilled water contained in a beaker. Add 15 ml of concentrated hydrochloric acid (relative density 1,18), stir and add slowly 30 ml of sodium hypochlorite solution (10 % to 15 % a
23、vailable chlorine). Add 5 ml of hydrogen peroxide (30 %) slowly with continuous stirring. Leave the solution in the open beaker for 24 h in a fume cupboard, to allow excess chlorine to escape, before use. NOTEThe solution does not deteriorate with age and therefore can be kept in a bottle with a loo
24、sely fitting glass stopper over a period of several months. 3.2Test solution B (see 5.3). Dissolve 50 g of lead acetate trihydrate (CH3COO)2Pb.3H2O in 1 l of distilled or de-ionized water. Ensure that the pH of the solution is between 5,5 and 6,8 as prepared. If the pH of the solution is outside thi
25、s range, discard the solution and obtain a new supply of lead acetate. Any white precipitate formed during the initial preparation of the solution may be dissolved by small additions of glacial acetic acid, provided that the pH is not reduced to a value below 5,5. Discard the stock solution if the w
26、hite precipitate does not disappear. 3.3Test solution C (see 5.5). Dissolve 0,4 g of diphenylcarbazide in a mixture of 20 ml acetone and 20 ml ethanol (96 %). After dissolution, add 20 ml of 75 % orthophosphoric acid solution and 20 ml of distilled water. Prepare this solution not more than 8 h prio
27、r to use. 3.4Test solution D (see 5.6 and 5.7). Dissolve 0,50 g of diphenylcarbazide in 50 ml of acetone. Dilute slowly, while stirring, with 50 ml of water (rapid mixing can result in precipitation of diphenylcarbazide). For maximum stability, store the solution under refrigeration in an amber-colo
28、ured glass bottle. ISO 3613:2000(E) ISO 2000 All rights reserved3 3.5Sulfuric acid, diluted 1 + 3. Slowly add 1 volume of concentrated sulfuric acid (relative density 1,84) to 3 volumes of water. 3.6Ammonium persulfate (NH4)2S2O8. 3.7Sodium hydroxide (NaOH), (240 g/l) solution. 3.8Silver nitrate (Ag
29、NO3), 17 g/l solution. 3.9Potassium dichromate (K2Cr2O7), standard solution. Dilute to 1 000 ml 2 ml of standard volumetric potassium dichromate solution (4,9 g/l). 3.10Phosphate buffer solution Dissolve 55 g of sodium dihydrogen orthophosphate monohydrate (NaH2PO4.H2O) in 100 ml water. 4Apparatus 4
30、.1Photoelectric absorptiometer (colorimeter), with a filter having a mean transmission of 520 nm. The absorptiometer shall be used with an absorption cell of optical path length 10 mm. 4.2Spectrophotometer, with wavelength set at 540 nm. The spectrophotometer shall be used with an absorption cell of
31、 optical path length 10 mm. 5Test methods 5.1General The test surface, prior to the following tests, shall be free of all contaminants, finger prints and other extraneous stains. If the surface is coated with thin oil, it shall be removed prior to the test by degreasing using a suitable solvent at r
32、oom temperature (not exceeding 35 C). For test purposes, the samples shall not be subjected to forced drying at temperatures in excess of 35 C. Treatment in alkaline solutions shall not be performed as chromate conversion coatings are broken down by alkalis. The test methods for a)the presence of a
33、colourless chromate coating on zinc, cadmium and aluminium-zinc alloy, b)the presence of hexavalent chromium in both coloured and colourless chromate coatings, c)the determination of hexavalent chromium content and d)the determination of total chromium content are given in 5.2 to 5.7. The tests shal
34、l be carried out within the following time limits: ?minimum 24 h after the application of the chromate conversion coating for all tests (5.2 to 5.10); ISO 3613:2000(E) 4 ISO 2000 All rights reserved ?maximum 3 d for tests specified in 5.2 to 5.52); ?maximum 30 d for tests specified in 5.6 and 5.7. T
35、he test methods for a)the determination of mass per unit area of chromate conversion coatings, b)adhesion by abrasion and c)the evaluation of the quality of chromate layer are given in 5.8, 5.9 and 5.10, respectively. 5.2Test for the presence of a colourless chromate coating on zinc Apply 1 drop of
36、test solution A (3.1) to the chromated zinc surface. The formation of a red or red-violet colour in the drop shall be deemed to indicate the presence of chromate film. 5.3Test for the presence of a colourless chromate coating on zinc and cadmium Place 1 drop of test solution B (3.2) on the surface t
37、o be tested. In the case of a zinc substrate, observe the appearance of the spot for 3 min. The formation of a dark or black stain at least 1 min after the application of the test solution shall be deemed to indicate the presence of a colourless chromate conversion coating. Black stain formation aft
38、er more than 3 min can be indicative of the presence of supplementary coatings, such as wax or oil. In the case of a cadmium substrate, observe the appearance of the spot for 1 min. The formation of a dark or black stain at least 5 s after the application of the test solution shall be deemed to indi
39、cate the presence of a colourless chromate conversion coating. Black stain formation after more than 1 min can be indicative of the presence of supplementary coatings, such as wax or oil. For comparison purposes, test an untreated surface similarly. Untreated zinc and cadmium surfaces or the surface
40、s that have been treated for chromate conversion coating but do not have continuous coating will react with the lead acetate solution to form a black stain on the untreated or bare zinc and cadmium surfaces almost immediately, within 2 s to 5 s, after the application of the test solution. NOTE 1Beca
41、use of the sensitivity of the method, the test is considered to be a quality control tool for the processor. Items with damaged chromate layers should not be tested by this method. NOTE 2Chromate conversion coatings exposed to temperatures above 60 C will have considerably reduced resistance to corr
42、osion in the accelerated test method (5.10), and will show black stain in less than 60 s on zinc, and less than 5 s on cadmium. NOTE 3No significance should be placed upon any differences in the reaction time to black spot formation between 1 min and 3 min on a zinc substrate, or between 5 s and 60
43、s on a cadmium substrate, with colourless chromate conversion treatment. Factors such as substrate surface texture (roughness), chromate film thickness variations (due to processing conditions), variations in the ambient temperature of the test, and precise pH control of the lead acetate solution ha
44、ve an influence on the reaction time and therefore preclude any rating based upon times beyond those already stated. Similarly, the test cannot be used to compare the corrosion protection of chromate conversion coatings made from various types of chromate treatment solutions. 2)This may require spec
45、ial arrangements to be made between the purchaser and the supplier. -,-,- ISO 3613:2000(E) ISO 2000 All rights reserved5 5.4Test for the presence of a colourless chromate coating on aluminium-zinc (55 % mass fraction aluminium) and zinc-aluminium (5 % mass fraction aluminium) alloys Expose the test
46、specimen for 24 h to an accelerated damp heat test in accordance with IEC 60068-2-30. The formation of a dark grey to black stain over the main part of the area shall be deemed to indicate the absence of chromate conversion coating. NOTEThis test does not have any significant effect on the surface a
47、ppearance if a chromate conversion coating is present. 5.5Test for the presence of hexavalent chromium in both colourless and coloured chromate coatings Place 1 drop to 5 drops of test solution C (3.3) on the surface to be tested. If hexavalent chromium is present, a red to violet colour will appear
48、 within a few minutes. Ignore any colour that appears much later, for example on drying. For comparison purposes, test an untreated surface similarly. NOTEThe treatment will not have any significant effect on the surface appearance. 5.6Determination of hexavalent chromium content of coloured chromat
49、e coatings 5.6.1Preparation of calibration graph 5.6.1.1To a series of five 250 ml volumetric flasks, add respectively 0 ml (i.e. the compensation solution), 10 ml, 20 ml, 30 ml and 40 ml standard potassium dichromate solution (3.9). Add to each flask 100 ml water and 3 ml sulfuric acid solution (3.5). To one flask add 3 ml test solution D (3.4) and mix well. Exactly 2 min after the addition of test solution D, add 25 ml phosphate buffer solution (3.1
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