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1、BRITISH STANDARD AEROSPACE SERIES BS EN 2101:1991 Specification for Chromic acid anodizing of aluminium and wrought aluminium alloys This European Standard EN 2101:1991 has the status of a British Standard BS EN 2101:1991 This British Standard was published under the authority of the Standards Board
2、 and comes into effect on 29 November 1991 BSI 07-1999 The following BSI references relate to the work on this standard: Committee reference ACE/44 Draft for comment 89/80185 DC ISBN 0 580 20096 5 Cooperating organizations The European Committee for Standardization, under whose supervision this Euro
3、pean Standard was prepared, comprises the national standards organizations of the following Western European countries. AustriaOesterreichisches Normungsinstitut BelgiumInstitut belge de normalisation DenmarkDansk Standardiseringsraad FinlandSuomen Standardisoimisliito, r.y. FranceAssociation franai
4、se de normalisation GermanyDeutsches Institut fr Normung e.V. GreeceHellenic Organization for Standardization IcelandTechnological Institute of Iceland IrelandNational Standards Authority of Ireland ItalyEnte Nazionale Italiano di Unificazione LuxembourgInspection du Travail et des Mines Netherlands
5、Nederlands Normalisatie-instituut NorwayNorges Standardiseringsforbund PortugalInstituto Portugus da Qualidade SpainAsociacin Espaola de Normalizacin y Certificacin SwedenStandardiseringskommissionen i Sverige SwitzerlandAssociation suisse de normalisation United KingdomBritish Standards Institution
6、 Amendments issued since publication Amd. No.DateComments BS EN 2101:1991 BSI 07-1999i Contents Page Cooperating organizationsInside front cover National forewordii Foreword2 Text of EN 21013 National appendix NA (informative)Inside back cover National appendix NB (informative)Inside back cover BS E
7、N 2101:1991 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 EN 2101:1991 “Aerospace series Chromic acid anodizing of aluminium and wrought aluminium alloys”, published by t
8、he European Committee for Standardization (CEN). EN 2101 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 a
9、pplication. 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, pages i and ii, the EN title page, pages 2 to 10, an inside back cover and a back cover. This standard has been upd
10、ated (see 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 EN 2101 July 1991 UDC 669.715.691.5:546.766-32:629.7 Descriptors: Aircraft industry, aluminium, aluminium all
11、oys, rolled products, anodizing, chromic acid, setting-up conditions, quality assurance, corrosion resistance, inspection English version Aerospace series Chromic acid anodizing of aluminium and wrought aluminium alloys Srie arospatiale Anodisation chromique de laluminium et des alliages daluminium
12、corroys Luft- und Raumfahrt Chromsure-Anodisieren von Aluminium und Aluminium-Knetlegierungen This European Standard was approved by CEN on 28 June 1990. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the sta
13、tus 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 Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A
14、version 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,
15、 Greece, 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 Stassart 36, B-1050 Brussels CEN 1991 Copyr
16、ight reserved to all CEN members Ref. No. EN 2101:1991 E EN 2101:1991 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
17、has successively received the approval of the National Association 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
18、, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. Contents Page Foreword2 1Scope and field of application3 2Purpose of anodizing3 3References3 4Material categories3 5Supporting jig3 6Processing seque
19、nce3 7Quality assurance4 8Designation5 Annex A Surface preparation recommendations7 Annex B Inspection of the absorbing ability by anthraquinone violet drop test8 Annex C Inspection of corrosion resistance by repeated immersion test in salt solution8 EN 2101:1991 BSI 07-19993 1 Scope and field of ap
20、plication This standard specifies the required characteristics for the performance of chromic acid anodizing with or without sealing as well as quality assurance of the coating obtained. It applies to parts in aluminium and wrought aluminium alloys of category 1 and 2 (see clause 4) used in aerospac
21、e construction when reference is made to this standard. 2 Purpose of anodizing 2.1 Type A: Unsealed anodizing It is used either as a surface preparation before paint application or as a preparation to a macrographic examination (structural condition, presence of metallurgical defects). 2.2 Type B: S
22、ealed anodizing It is intended for corrosion protection. It shall be with or without colouring and used with or without additional painting. 3 References ISO 1463:1982, Metallic and oxide coatings Measurement of coating thickness Microscopical method. ISO 2085:1976, Anodizing of aluminium and its al
23、loys Check of continuity of thin anodic oxide coatings Copper sulphate test. ISO 2106:1982, Anodizing of aluminium and its alloys Determination of mass per unit area (surface density) of anodic oxide coatings Gravimetric method. ISO 2143:1981, Anodizing of aluminium and its alloys Estimation of loss
24、 of absorptive power of anodic oxide coatings after sealing Dye spot test with prior acid treatment. ISO 2360:1982, Non-conductive coatings on non-magnetic basis metals Measurement of coating thickness Eddy current method. ISO 2376:1972, Anodization (anodic oxidation) of aluminium and its alloys Ins
25、ulation check by measurement of breakdown potential. ISO 3768:1976, Metallic coatings Neutral salt spray test (NSS test). EN 2334, Aerospace series Acid chromate pickle for aluminium alloys1). 4 Material categories 4.1 Category 1 Pure aluminium, clad alloys, alloys characterised by the absence of co
26、pper or with a copper content limited to 1 %. 4.2 Category 2 Non-clad alloys containing 1 % copper: Category 2 A: solution heat treated, quenched and naturally aged condition Category 2 B: solution heat treated, quenched plus artificially aged condition. 5 Supporting jig The supporting jig (e.g. in
27、aluminium alloy or titanium) shall provide effective electrical contact with the parts. This contact is preferably achieved at several points to ensure better current distribution. 6 Processing sequence 6.1 Cleaning (see Annex A) The cleaning method used shall be appropriate for the contamination ex
28、perienced on the materials treated. Solvent degreasing followed by cleaning in an alkaline bath is generally the most effective method. 1) In preparation at the date of publication of this standard. EN 2101:1991 4 BSI 07-1999 6.2 Pickling (see Annex A) The pickling operation shall remove natural oxi
29、des 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 specified. As a general rule, pickling is conducted in a sul
30、phuric-chromic acid bath, but in exceptional cases, for certain alloys of category 2, 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 immersion followed by running water spray. It is recommended
31、 that rinsing in ordinary water is followed by rinsing in deionized or distilled water. 6.4 Anodizing 6.4.1 Electrolyte Aqueous solution of chromic acid (99,5 % min. CrO3) at a concentration of 30 g/l to 150 g/l to which certain additional agents such as oxalic acid may be added. The impurity conten
32、t shall be less than: Chlorides: 200 mg/l expressed as NaCl, Sulphates: 500 mg/l expressed as H2SO4. The chromic acid anodizing bath shall be made up with deionized water of a resistivity of more than 1057.cm unless sufficiently pure ordinary water is available. 6.4.2 Treatment conditions The anodiz
33、ing 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 bath. NOTEThe treatment of materials
34、 of different categories in one anodizing batch shall be avoided. 6.5 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 as possible and 16 h max. after ano
35、dizing. 6.6 Sealed anodizing The sealing quality stipulated in this standard requires the use of water having a resistivity greater than 1057.cm when made up. The pH shall be between 5,5 and 6,9. The temperature of the sealing bath shall not be less than 97 C. For alloys of category 2, sealing shall
36、 preferably be applied with the addition in deionized water of not less than 30 mg/l potassium dichromate, with a resistivity greater than 1057.cm. 6.7 Removal of the anodic coating (see Annex A) The method used to remove the anodic coating shall be such that, when reanodized, the dimensions and sur
37、face roughness shall conform with the values specified. 7 Quality assurance The required 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 qualificatio
38、n of a new installation and for continuous quality monitoring: 7.1.1 Chemical analysis of the bath on make up and during operation (see clause 6.4.1). EN 2101:1991 BSI 07-19995 7.1.2 Measurement of resistivity and pH of the sealing bath (see clause 6.6). 7.1.3 Corrosion tests These tests (see Table)
39、 are applicable for anodized and sealed parts only. Not less than 5 rectangular specimens of the minimum dimensions of 60 mm 120 mm, thickness optional, representative of the treated parts (material, heat treatment, surface finish) shall be anodized and sealed. If it is impossible to produce rectang
40、ular specimens, the surface exposed to corrosion for each specimen shall be practically equivalent. 7.1.4 The frequency of 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 prac
41、ticable to perform the quality control on processed parts, test pieces which are representative of a part or of a batch of parts which have been processed the same way and 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 In
42、spection (see Table) The quality assurance authority specifies the number of parts to be inspected per batch or parts to be subjected to individual inspection. 7.3 Test report The test report shall state the following: Reference to this standard Type of anodizing (type A or B) Category of the materi
43、al and its heat treatment Date of anodizing Batch number Test results. 8 Designation The following designation shall be indicated on the relevant documents: NOTEIf necessary, the originator code 19005 may be introduced between the description block and the identity block. EN 2101:1991 6 BSI 07-1999
44、Table Nature of testTest method Anodizing SealedUnsealed Material categoryMaterial category 12A2B12A2B AppearanceVisualNo powdering Minimum thickness (m)a ISO 1463c ISO 2360 ISO 2106 2,51,512,51,51 Loss of absorptive power ISO 2143 No persistence of colourant stain (intensity if stain: 0 or 1) No te
45、st Annex BNo indelible residual stain Corrosion resistancebISO 3768c or Annex C No corrosion after 500 h300 h Coating continuityISO 2085dNo black pointNo test Average insulation (V)a ISO 2376300200150200150100 a Unsatisfactory results of thickness and insulation measurements are not a cause for reje
46、ction: For sealed anodizing: If the results of corrosion testing are satisfactory, or if there are no particular electrical insulation requirements. For unsealed anodizing: Acceptance or rejection is left to the discretion of the Official Services or of competent Authority who shall consider the res
47、ults depending upon anodizing process conditions and the intended use of the anodized part. b Except at points of electrical contact during anodizing or at points of marking. c Reference method. d Without thickness restriction. EN 2101:1991 BSI 07-19997 Annex A Surface preparation recommendations A.
48、1 Scope This annex specifies the cleaning and pickling processes to be used as preliminary treatment. Any other process giving at least equivalent results is acceptable. A.2 Degreasing A.2.1 Organic solvents a) Hot solvents non-water washable Halogenated hydrocarbons in the liquid or vapour phase su
49、ch as trichlorethylene, perchlorethylene, trichlorotrifluoroethane and 1-1-1 trichloroethane. b) Cold solvents non-water washable Solvents in the liquid phase such as those listed under a) and white spirit. It can be applied by immersion, spraying or manually. When the parts are degreased by immersion in the solvents, at least 3 successive immersions shall be applied. When the solvent is contamined by grease, it shall be replaced. A.2.2 Alkaline Used alone or in addition to preliminary solvent