1、BRITISH STANDARD AEROSPACE SERIES BS EN 2101:1991 Specification for Chromic acid anodizing of aluminium and wrought aluminium alloys This European Standard EN2101:1991 has the status of a British StandardBSEN2101:1991 This British Standard was published under the authority ofthe Standards Board and
2、comesinto effect on 29November1991 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 European Sta
3、ndard was prepared, 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
4、de normalisation 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 Netherla
5、nds Nederlands Normalisatie-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 I
6、nstitution Amendments issued since publication Amd. No. Date CommentsBSEN2101:1991 BSI 07-1999 i Contents Page Cooperating organizations Inside front cover National foreword ii Foreword 2 Text of EN 2101 3 National appendix NA (informative) Inside back cover National appendix NB (informative) Inside
7、 back coverBSEN2101:1991 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 EN2101:1991 “Aerospace series Chromic acid anodizing of aluminium and wrought aluminium alloys”, pu
8、blished by the European Committee for Standardization (CEN). EN2101 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 thei
9、r correct application. 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 h
10、as been updated (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, alu
11、minium alloys, 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 d
12、aluminium corroys Luft- und Raumfahrt Chromsure-Anodisieren von Aluminium und Aluminium-Knetlegierungen This European Standard was approved by CEN on28June1990. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
13、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 Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, Germ
14、an). A 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, G
15、ermany, 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 CEN1991
16、 Copyright reserved to all CEN members Ref. No. EN2101:1991 EEN2101:1991 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 Standa
17、rd 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, Denm
18、ark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. 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 P
19、rocessing sequence 3 7 Quality assurance 4 8 Designation 5 Annex A Surface preparation recommendations 7 Annex B Inspection of the absorbing ability by anthraquinone violet drop test 8 Annex C Inspection of corrosion resistance by repeated immersion test in salt solution 8EN2101:1991 BSI 07-1999 3 1
20、 Scope and field of application 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 category1and2 (see clause4
21、) used in aerospace 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 defec
22、ts). 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. 3 References ISO 1463:1982, Metallic and oxide coatings Measurement of coating thickness Microscopical method. ISO 2085:1976, Anodizing of al
23、uminium and its alloys 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
24、Estimation of loss 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
25、and its alloys Insulation 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 alloys 1) . 4 Material categories 4.1 Category 1 Pure aluminium, clad alloys, alloys characterised
26、by the absence of copper or with a copper content limited to1%. 4.2 Category 2 Non-clad alloys containing 1 % copper: Category2 A: solution heat treated, quenched and naturally aged condition Category2 B: solution heat treated, quenched plus artificially aged condition. 5 Supporting jig The supporti
27、ng jig (e.g. in 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 (seeAnnex A) The cleaning method used shall be appropriate for the c
28、ontamination experienced 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.EN2101:1991 4 BSI 07-1999 6.2 Pickling (seeAnnex A) The pickling operation shall remove
29、 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 specified. As a general rule, pickling is conduc
30、ted 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 immersion followed by running water spray. It is
31、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 chromic acid (99,5 % min. CrO 3 ) at a concentration of30g/l to150g/l to which certain additional agents such as oxalic acid may be added. The impuri
32、ty content shall be less than: Chlorides: 200 mg/l expressed as NaCl, Sulphates: 500mg/l expressed as H 2 SO 4 . The chromic acid anodizing bath shall be made up with deionized water of a resistivity of more than10 5 7.cm unless sufficiently pure ordinary water is available. 6.4.2 Treatment conditio
33、ns The anodizing 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
34、 of materials 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 and16h max
35、. after anodizing. 6.6 Sealed anodizing The sealing quality stipulated in this standard requires the use of water having a resistivity greater than10 5 7.cm when made up. The pH shall be between5,5 and6,9. The temperature of the sealing bath shall not be less than97 C. For alloys of category2, seali
36、ng shall preferably be applied with the addition in deionized water of not less than30mg/l potassium dichromate, with a resistivity greater than10 5 7.cm. 6.7 Removal of the anodic coating (seeAnnex A) The method used to remove the anodic coating shall be such that, when reanodized, the dimensions a
37、nd surface 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 qualif
38、ication of a new installation and for continuous quality monitoring: 7.1.1 Chemical analysis of the bath on make up and during operation (seeclause6.4.1).EN2101:1991 BSI 07-1999 5 7.1.2 Measurement of resistivity and pH of the sealing bath (seeclause6.6). 7.1.3 Corrosion tests These tests (see Table
39、) are applicable for anodized and sealed parts only. Not less than5 rectangular specimens of the minimum dimensions 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 rectangula
40、r 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 practic
41、able 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 Inspe
42、ction (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 material
43、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 code19005may be introduced between the description block and the identity block.EN 2101:1991 6 BSI 07-1999 Table
44、Nature of test Test method Anodizing Sealed Unsealed Material category Material category 1 2A 2B 1 2A 2B Appearance Visual No powdering Minimum thickness (m) a ISO 1463 cISO 2360 ISO 2106 2,5 1,5 1 2,5 1,5 1 Loss of absorptive power ISO 2143 No persistence of colourant stain (intensity if stain: 0 o
45、r1) No test Annex B No indelible residual stain Corrosion resistance b ISO 3768 cor Annex C No corrosion after 500 h 300 h Coating continuity ISO 2085 d No black point No test Average insulation (V) a ISO 2376 300 200 150 200 150 100 a Unsatisfactory results of thickness and insulation measurements
46、are not a cause for rejection: 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 wh
47、o shall consider the results depending upon anodizing process conditions andthe 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.EN2101:1991 BSI 07-1999 7 Annex A Surface preparat
48、ion recommendations A.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 liq
49、uid or vapour phase such as trichlorethylene, perchlorethylene, trichlorotrifluoroethane and1-1-1 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 least3successive 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 pr
