1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN ISO 8994:2011Anodizing of aluminium and itsalloys Rating system for theevaluation of pitting corrosion Grid method (ISO 8994:2011)BS EN ISO 8994:2011 BRITISH STANDARDNation
2、al forewordThis British Standard is the UK implementation of EN ISO 8994:2011.It supersedes BS EN 12373-19:2001 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee STI/32, Anodic oxidation coatings on aluminium.A list of organizations represented on this co
3、mmittee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2011ISBN 978 0 580 66156 3ICS 25.220.20; 77.060Compliance with a British Standard cannot confer immunity fr
4、omlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 March 2011.Amendments issued since publicationDate Text affectedEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 8994 March 2011 ICS 77.060; 25.220.20 Supersedes EN
5、 12373-19:2001English Version Anodizing of aluminium and its alloys - Rating system for the evaluation of pitting corrosion - Grid method (ISO 8994:2011) Anodisation de laluminium et de ses alliages - Systme de cotation de la corrosion par piqres - Mthode par quadrillage (ISO 8994:2011) Anodisieren
6、von Aluminium und Aluminiumlegierungen - Bewertungssystem fr Lochkorrosion - Rasterzhlmethode (ISO 8994:2011) This European Standard was approved by CEN on 28 February 2011. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this Europ
7、ean Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. This European Standard exists in three official versions
8、 (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Bel
9、gium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COM
10、MITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2011 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 8994:2011: EBS EN ISO 8994:2011E
11、N ISO 8994:2011 (E) 3 Foreword This document (EN ISO 8994:2011) has been prepared by Technical Committee ISO/TC 79 “Light metals and their alloys“ in collaboration with Technical Committee CEN/TC 132 “Aluminium and aluminium alloys” the secretariat of which is held by AFNOR. This European Standard s
12、hall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by September 2011, and conflicting national standards shall be withdrawn at the latest by September 2011. Attention is drawn to the possibility that some of the elements of th
13、is document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 12373-19:2001. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countri
14、es are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Sloveni
15、a, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of ISO 8994:2011 has been approved by CEN as a EN ISO 8994:2011 without any modification. BS EN ISO 8994:2011ISO 8994:2011(E) ISO 2011 All rights reserved iiiForeword ISO (the International Organization for Standardiza
16、tion) 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 which a technical committee has been established has the right to be
17、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 all matters of electrotechnical standardization. International Standard
18、s are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an Interna
19、tional Standard 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 document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 8994 was
20、prepared by Technical Committee ISO/TC 79, Light metals and their alloys, Subcommittee SC 2, Organic and anodic oxidation coatings on aluminium. This second edition cancels and replaces the first edition (ISO 8994:1989), which has been technically revised. BS EN ISO 8994:2011BS EN ISO 8994:2011INTER
21、NATIONAL STANDARD ISO 8994:2011(E) ISO 2011 All rights reserved 1Anodizing of aluminium and its alloys Rating system for the evaluation of pitting corrosion Grid method 1 Scope This International Standard specifies a grid rating system that provides a means of defining levels of performance of anodi
22、c oxidation coatings on aluminium and its alloys that have been subjected to corrosion tests. This rating system is applicable to pitting corrosion resulting from accelerated tests, exposure to corrosive environments, and practical service tests. This International Standard takes into account only p
23、itting corrosion of the basis metal resulting from penetration of the protective anodic oxidation coating. NOTE 1 ISO 89933describes a similar rating system based on defined chart scales. NOTE 2 The grid rating system is frequently used for rating the results of short-term corrosion tests for relati
24、vely thin anodic oxidation coating, such as those used in the automotive industry. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1 significant surface part of the article covered or to be covered by the coating, for which the coating is essen
25、tial for serviceability and/or appearance NOTE 1 Adapted from ISO 2064:19961, definition 3.1. NOTE 2 The edges of an article are not normally included in the significant surface. 2.2 corrosion pit surface corrosion defect at which the anodic oxidation coating is penetrated NOTE Discoloration or othe
26、r surface defects which do not penetrate the anodic coating do not count as corrosion pits. BS EN ISO 8994:2011ISO 8994:2011(E) 2 ISO 2011 All rights reserved3 Procedure for rating 3.1 Sample preparation A sample area of more than 5 000 mm2is required. Use one of the following methods to remove corr
27、osion products or deposits on the surface so that corrosion pits may be clearly discerned: a) wipe with a slurry of fine pumice to abrade away corrosion products and dirt, then rinse in clean water and air dry; or b) dip for 5 min to 10 min in 30 % nitric acid, prepared by diluting 1 volume of conce
28、ntrated nitric acid (20= 1,40 g/ml) with 1 volume of water at 20 C to 25 C; rinse and dry as indicated in a); or c) dissolve the anodic oxidation coating in a hot phosphoric acid/chromic acid mixture; rinse and dry as indicated in a) so that pitting in the aluminium substrate may be discerned; NOTE
29、1 ISO 21062describes the preparation and use of this reagent for the purposes of dissolution of the anodic oxidation coating. NOTE 2 This method is particularly useful for dark-coloured anodic oxidation coatings. WARNING Chromium(VI) is toxic and shall be handled properly. Chromium(VI) solutions are
30、 hazardous to the environment and severely hazardous to waters. or d) wipe with soft textile gauze dipped in dilute hydrochloric acid solution (100 ml of 35 % to 37 % HCl, made up to 1 000 ml with distilled water or deionized water) to remove deposited copper, then rinse and dry as indicated in a).
31、3.2 Determination of grid rating Place a preprinted transparent grid with an area of at least 5 000 mm2, and with grid squares of 5 mm 5 mm, over a selected area of the significant surface of the prepared test specimen. Count the number of grid squares occupied by one or more pits, disregarding effe
32、cts on the edges of samples. Calculate the percentage of defective squares, i.e. grid squares containing pits, using Formula (1): 100tNN (1) where N is the number of defective squares; Ntis the total number of squares. Determine the grid rating from Table 1. BS EN ISO 8994:2011ISO 8994:2011(E) ISO 2
33、011 All rights reserved 3Table 1 Conversion of percentage of defective squares to grid rating Frequency of defective squares % Defective squares, N, of 200 squares, NtRating number 0 0 0 u0,5 1 1 0,5 to 1 2 2 1 to 2 3 or 4 3 2 to 4 5 to 8 6 4 to 8 9 to 16 12 8 to 16 17 to 32 25 16 to 32 33 to 64 50
34、32 to 64 65 to 128 100 64 128 200 NOTE The greater the number of squares, the more discriminating is the performance level. 4 Expression of results Express the result of the examination as the grid rating and/or the percentage of defective squares, as appropriate. 5 Test report The test report shall
35、 include at least the following information: a) a reference to this International Standard; b) the type and identification of the product tested and, where appropriate, the anodizing, exposure and corrosion test procedure; c) the method of sample preparation used (see 3.1); d) the grid rating and/or
36、 the percentage of defective squares (see Clause 4); NOTE The acceptable grid rating will normally be specified in the relevant corrosion test or product specification. e) the date of the test. BS EN ISO 8994:2011ISO 8994:2011(E) 4 ISO 2011 All rights reservedBibliography 1 ISO 2064:1996, Metallic a
37、nd other inorganic coatings Definitions and conventions concerning the measurement of thickness 2 ISO 2106, Anodizing of aluminium and its alloys Determination of mass per unit area (surface density) of anodic oxidation coatings Gravimetric method 3 ISO 8993, Anodizing of aluminium and its alloys Ra
38、ting system for the evaluation of pitting corrosion Chart method BS EN ISO 8994:2011This page deliberately left blankThis page deliberately left blankBSI is the independent national body responsible for preparing British Standardsand other standards-related publications, information and services. It
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