1、BRITISH STANDARD BSEN 2284:1991 Specification for Sulfuric acid anodizing of aluminium and wrought aluminium alloys This European Standard EN2284:1991 has the status of a British StandardBSEN 2284:1991 This British Standard was published under the authorityofthe Standards Boardand comes into effect
2、on 29 November1991 BSI 07-1999 The following BSI references relate to the work on this standard: Committee reference ACE/44 Draft for comment 89/80186 DC ISBN 0 580 20097 3 Cooperating organizations The European Committee for Standardization, under whose supervision this European Standard was prepar
3、ed, comprises the national standards organizations of the following Western European countries. Austria Oesterreichisches Normungsinstitut Belgium Institut belge de normalisation Denmark Dansk Standardiseringsraad Finland Suomen Standardisoimisliito, r.y. France Association franaise de normalisation
4、 Germany Deutsches Institut fr Normung e.V. Greece Hellenic Organization for Standardization Iceland Technological Institute of Iceland Ireland National Standards Authority of Ireland Italy Ente Nazionale Italiano di Unificazione Luxembourg Inspection du Travail et des Mines Netherlands Nederlands N
5、ormalisatie-instituut Norway Norges Standardiseringsforbund Portugal Instituto Portugus da Qualidade Spain Asociacin Espaola de Normalizacin y Certificacin Sweden Standardiseringskommissionen i Sverige Switzerland Association suisse de normalisation United Kingdom British Standards Institution Amend
6、ments issued since publication Amd. No. Date CommentsBSEN 2284:1991 BSI 07-1999 i Contents Page Cooperating organizations Inside front cover National foreword ii Foreword 2 Text of EN2284 3 National appendix NA (informative) Inside back cover National appendix NB (informative) Inside back coverBSEN
7、2284:1991 ii BSI 07-1999 National foreword This British Standard has been prepared under the direction of the Aerospace Standards Policy Committee and is the English language version of EN2284:1991 “Aerospace series Sulphuric acid anodizing of aluminium and wrought aluminium alloys”, published by th
8、e European Committee for Standardization (CEN). EN2284 was produced as a result of international discussion in which the UK took an active part. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct app
9、lication. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, theENtitle page, pages2 to8, an inside back cover and a back cover. This standard has been updated (see
10、 copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN2284 July 1991 UDC669.715.691.5:546.226-325:629.7 Descriptors: Aircraft industry, aluminium, aluminium alloys, rolled
11、 products, anodizing, sulphuric acid, setting-up conditions, quality assurance, corrosion resistance, inspection English version Aerospace series Sulphuric acid anodizing of aluminium and wrought aluminium alloys Srie arospatiale Anodisation sulfurique de laluminium et des alliages daluminium corroy
12、s Luft- und Raumfahrt Schwefelsure-Anodisieren von Aluminium und Aluminium-Knetlegierungen This European Standard was approved by CEN on28 June1990. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status o
13、f a 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 versi
14、on in 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, Gree
15、ce, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and UnitedKingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels CEN 1991 Copyright r
16、eserved to all CEN members Ref. No. EN2284:1991 EEN 2284:1991 BSI 07-1999 2 Foreword This European Standard has been prepared by the European Association of Aerospace Manufacturers (AECMA). After inquiries and votes carried out in accordance with the rules of this Association, this Standard has succ
17、essively received the approval of the National Associations and the Official Services of the member countries of AECMA, prior to its presentation to CEN. According to the Common CEN/CENELEC Rules, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finla
18、nd, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and UnitedKingdom. Contents Page Foreword 2 1 Scope and field of application 3 2 Purpose of anodizing 3 3 References 3 4 Material categories 3 5 Supporting jig 3 6 Processing s
19、equence 4 7 Quality assurance 5 8 Designation 7 Table 6EN2284:1991 BSI 07-1999 3 1 Scope and field of application This standard specifies the required characteristics for the performance of sulphuric acid anodizing with or without sealing as well as quality assurance of the coating obtained. It appl
20、ies to parts in aluminium and wrought aluminium alloys of category1 and2 (see clause4) used in aerospace construction when reference is made to this standard. 2 Purpose of anodizing 2.1 Type A: Unsealed anodizing It shall be used either as surface preparation before the application of paint or any o
21、ther finish. 2.2 Type B: Sealed anodizing It is intended for corrosion protection. It shall be with or without colouring and used with or without additional painting. NOTESulphuric acid anodizing diminishes the fatigue characteristics of the parts; therefore its application shall be avoided for part
22、s subject to high fatigue stress. 3 References ISO1463:1982, Metallic and oxide coatings Measurement of coating thickness Microscopical method. ISO2085:1976, Anodizing of aluminium and its alloys Check of continuity of thin anodic oxide coatings Copper sulphate test. ISO2106:1982, Anodizing of alumi
23、nium and its alloys Determination of mass per unit area (surface density) of anodic oxide coatings Gravimetric method. ISO2143:1981, Anodizing of aluminium and its alloys Estimation of the loss of absorptive power of anodic oxide coatings after sealing Dye spot test with prior acid treatment. ISO236
24、0:1982, Non-conductive coatings on non-magnetic basis metals Measurement of coating thickness Eddy current method. ISO2376:1972, Anodization (anodic oxidation) of aluminium and its alloys Insulation check by measurement of breakdown potential. ISO3768:1976, Metallic coatings Neutral salt spray test
25、(NSS test). EN2101, Aerospace series Chromic acid anodizing of aluminium and wrought aluminium alloys. EN2334, Aerospace series Acid chromate pickle for aluminium alloys 1) . 4 Material categories 4.1 Category1 Pure aluminium, clad alloys, alloys characterised by the absence of copper or with a copp
26、er content limited to1%. 4.2 Category2 Non-clad alloys containing 1% copper (classified only according to their heat treatment condition): Category2 A: solution heat treated, quenched and naturally aged condition Category2 B: solution heat treated, quenched plus artificially aged condition. 5 Suppor
27、ting jig The supporting jig (e.g.in aluminium alloy or titanium) shall provide effective electrical contact with theparts. This contact is preferably achieved at several points in order to ensure better current distribution. 1) In preparation at the date of publication of this standard.EN 2284:1991
28、4 BSI 07-1999 6 Processing sequence 6.1 Cleaning (see EN2101, Annex A) The cleaning method used shall be appropriate for the contamination experienced on the materials treated. Solvent degreasing followed by cleaning in an alkaline bath is generally the most effective method. 6.2 Pickling (see EN210
29、1, Annex A) The pickling operation shall remove natural oxides in order to obtain correct anodizing; it shall neither degrade the metallurgical properties of the material nor the material fatigue behaviour, nor initiate pitting. It shall not degrade the dimensional tolerances and surface roughness s
30、pecified. As a general rule, pickling is conducted in a sulphuric/chromic acid bath, but in exceptional cases, for certain alloys of category2, alkaline pickling may be used. 6.3 Rinsing All rinsing operations before anodizing shall be effective and complete. For example, they may be performed by im
31、mersion followed by running water spray. It is recommended that rinsing in ordinary water is followed by rinsing in deionized or distilled water. 6.4 Anodizing 6.4.1 Electrolyte Aqueous solution of sulphuric acid ( 20C=1,84g/cm 3 ) at a concentration of90g/l to400g/l, to which additional agents can
32、be added, with the agreement of the quality assurance authority. The impurity content shall be less than chloride:200mg/l expressed as NaCl. The sulphuric acid anodizing bath shall be made up with deionised water of a resistivity of more than10 5 7.cm, unless sufficiently pure ordinary water is avai
33、lable. 6.4.2 Treatment conditions The parameters (temperature, voltage, time) shall be adapted to the material and its category in accordance with the bath composition. The control system shall make it possible to maintain the treatment temperature within a tolerance of 2 C in a suitably agitated ba
34、th. NOTEThe treatment of materials of different categories in one anodizing batch shall be avoided. 6.4.3 Unsealed anodizing In this case, it is necessary to take great precautions to avoid contamination of the oxide coating during handling. If a paint finish is required it shall be applied as soon
35、as possible and16hmax. after anodizing. 6.4.4 Coloured anodizing If required any colouring of the parts shall be carried out immediately after anodizing and careful rinsing. It is carried out in an aqueous solution in accordance with the conditions (concentration, pH, time, temperature, etc.) given
36、by the dye manufacturer and after comparison with the given colour sample. After colouring and before sealing a careful rinsing in water at a temperature less than50 C shall be carried out. 6.4.5 Sealed anodizing On coloured pieces, sealing is performed in pure water, or in pure water to which has b
37、een added a compound designed to prevent removal of the colouring agents. On pieces which are not coloured, it is carried out in pure water, or in water containing an inhibitor, after careful rinsing. 6.4.5.1 Sealing in pure water The quality of sealing required by this standard necessitates the use
38、 of water of a resistivity of more than10 5 7.cm when made up. The pH shall be between5,5 and6,9. The bath temperature shall be no less than97 C. The sealing bath shall be renewed when the resistivity isu 10 5 7.cm.EN2284:1991 BSI 07-1999 5 6.4.5.2 Sealing with addition of an inhibitor In this case,
39、 an inhibitor is added to the deionized water in order to increase the protective power of the anodic coating (e.g.potassium dichromate). The bath temperature shall be not less than97 C and the pH shall be between5,5 and6,9. The inhibitor concentration shall be established and maintained within limi
40、ts which ensure the quality specified by this standard. 6.5 Removal of the anodic coating (see EN2101, Annex A) The method used to remove the anodic coating shall be such that, when reanodised, the dimensions and surface roughness shall conform with the values specified. 7 Quality assurance The requ
41、ired quality is achieved by carrying out at the same time tests on the bath efficiency and inspection of treated parts as follows: 7.1 Check for bath efficiency The following tests shall be conducted for qualification of a new installation and for continuous quality monitoring: 7.1.1 Chemical analys
42、is of the bath on make up and during operation (see clause6.4.1). 7.1.2 Measurements of resistivity and pH of the sealing bath (see clause6.4.5). 7.1.3 Corrosion tests These tests (see Table) are applicable to anodized and sealed parts only. Not less than5 rectangular specimens of the minimum dimens
43、ions of60mm 120mm, thickness optional, representative of the treated parts (material, heat treatment, surface finish) shall be anodized and sealed. If it is impossible to produce rectangular specimens, the surface exposed to corrosion for each specimen shall be practically equivalent. 7.1.4 The freq
44、uency of the inspection of bath efficiency is laid down by the official services or at the discretion of the quality assurance Authority. 7.2 Inspection of treated parts Where it is not practicable to perform the quality control on processed parts, test pieces, which are representative of a part or
45、of a batch of parts which have been processed the same way at the same time shall be used. 7.2.1 Batching A batch consists of all parts treated at the same time in the same bath. 7.2.2 Inspection (see Table) The quality assurance specifies the number of parts to be inspected per batch or parts to be
46、 subjected to individual inspection. NOTEA maximum thickness may be specified on the drawing for special cases, e.g.parts subject to high fatigue stress, rivets, etc. 7.3 Test report The test report shall indicate the following: Reference to this standard Type of anodizing (A or B), with or without
47、colouring Category of the material and heat treatment Date of anodizing Batch number Test results.EN 2284:1991 6 BSI 07-1999 Table Nature of test Test method Anodizing Sealed Unsealed 1 2 1 2 Appearance Visual No powdering Minimum thickness (m) a ISO1463 c ISO2360 ISO2106 12 25 6 12 12 25 6 12 Loss
48、of absorptive power ISO2143 No persistence of colourant stain (intensity of stain:0or1) No test EN2101 Annex B No indelible residual stain Corrosion resistance b ISO3768 c or EN2101 Annex C No corrosion after750h No corrosion after500h Coating continuity ISO2085 d No black point No black point excep
49、t2B Average insulation (V) a ISO2376 1000 500 1000 500 a Unsatisfactory results of thickness and insulation measurements are not a cause for rejection: For sealed anodizing: If the results of the corrosion tests are satisfactory or if there are no particular electrical insulation requirements. For unsealed anodizing: The acceptance or rejection shall be left to the initiative of the Official Services or competent Authority who shall consider the results depending upon anodizing process cond
