1、2334 : 1997 Chromic-sulphuric acid pickle of aluminium and aluminium alloys The European Standard EN 2334 : 1997 has the status of a British Standard ICs 49.040 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW - STDmBSI BS EN 233Li-ENGL 1777 D Lb24bb7 Ob57Lii7 b7 BS EN 2334 : 1
2、997 This British Standard, having been prepared under the direction of the Engineering Sector Board, was published under the authorily of the Standards Board and comes into effect on 15 November 1997 National foreword This British Standard is the English language version of EN 2334 : 1997. The UK pa
3、rticipation in its preparation was entrusted to Technical Committee ACE44, Protective treatments and aircraft finishes, which has the responsibility to: - aid enquirers to understand the text; - present to the responsible European committee any enquiries on the interpretation, or proposais for chang
4、e, and keep the UK interests informed - monitor related international and European developments and promulgate them in the UK A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or Eur
5、opean publications referred to in this document may be found in the BSI Standards Catalogue under the section entitied International Standards Correspondence Index, or by using the Find facility of the BSI Standards Electronic Catalogue. NOTE. Under the AECMA part numbering system, normative referen
6、ces to the Parts of AECMA- originated European Standards may appear in clause 2 in the form of a three-digit number e.g -001 where the BSI and CEN systems would use the form -1. It can be assumed that, wherever referenced, the threedigit and single digit forms can be used interchangeably. For the pu
7、rposes of part-marking of components produced in accordance with this standard, the three-digit form should be used. 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, the EN tit
8、ie page, pages 2 to 8, an inside back cover and a back cover. Amendments issued since publication Amd.No. IDate 1 Text affected O BSI 1997 ISBN O 580 28135 3 STD-BSI BS EN 23q4-ENGL 1997 i lb24bb7 Ob59450 390 D EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 2334 July 1997 ICs 69.040.60 Descrip
9、tors: aircraft industry, aluminium. aluminium alloys, cleaning English version * * m European Cornnittee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rwi dc Stassart.36 6-1050 Brussels Aerospace series - Chromic-sulphuric acid pickle of alumi
10、nium and aluminium alloys Srie arospatiale - Dcapage sulfochromiquc de laluniniun et des alliages dfaluniniun Luft- und Raunfahrt - Beizen von Aluniniun und ALuniniunlegierungen in Chrmchuefelsure This European Standard vas approved by CEN on 1996-08-04. CEN members are bound to canply uith the CENK
11、ENELEC Internal Regulations uhich stipulate the conditions for giving this European Standard the status of a national standard uithout any alteration. up-to-date lists and bibliographicat references concerning such national standards may be obtained on application to the Central Secretariat or to an
12、y CEN member. lhe European Standards exist in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its om language and notified to the Central Secretariat has the same status as the official versions. CEN
13、 members are the national standards bodies of Austria, Belgiun, Czech Republic, Denmark, Finlend, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sudpn, Suitzerlard and United Ki ngdom. 0 1997 CEN - All rights of exploitation in any form and by any
14、 means reserved uorlduide for CEN national Members. Ref. No. EN 2334:1997 E Page 2 EN 2334:1997 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, th
15、is Standard has received the approval of the National Associations and the Official Services of the member countries of AECMA, prior to its presentation to CEN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at t
16、he latest by January 1998, and conflicting national standards shall be withdrawn at the latest by January 1998. According to the CENEENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Rep
17、ublic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. STD.BS1 BS EN 2334-ENGL 1997 m Lb24bb7 Ob59452 Lb3 m Page 3 EN 2334 : 1997 1 Scope This standard specifies the acid chromate pickli
18、ng of aluminium and aluminium alloys except those with a silicon content in excess of 2 % or a copper content in excess of 5 %. It is applicable whenever referenced. 2 Normative references This European Standard incorporates by dated or undated reference provisions from other publications. These nor
19、mative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated ref
20、erences the latest edition of the publication referred to applies. EN 2000 Aerospace series - Quality assurance EN aerospace products - Approval of the quality system of manufacturers 3 Purpose of process 3.1 specimens used for qualification and acceptance tests on adhesives, paints, sealants (treat
21、ment A) Reference surface treatment, e.g. prior to adhesive bonding or primer application to test 3.2 Final treatment for parts prior to adhesive bonding or primer application (treatment B) 3.3 Pre-treatment prior to anodizing for adhesive bonding (treatment C) 3.4 - anodizing for other applications
22、 than adhesive bonding ; - other chemical treatments. Pre-treatment (treatment DI for : 4 Information for the processor - Designation, see 13 - Number of the material standard and metallurgical condition of the latter - Sequence of operations - Areas to be processed - Treatment 5 Condition. of parts
23、 prior to processing Fabrication of the parts shall have been completed before pickling. Page 4 EN 2334 : 1997 Process schedule Pre-treatments Pickling Post-treatments 6 Process schedule The pickling process shall be performed according to table 1. Table 1 Application, see treatment A B C D 7.1 7.2
24、7.2 7.2 8 8 8 8 9.1 9.1 9.1 9.1 9.2 9.2 9.3 9.3 7 Pre-treatments 7.1 Cleaning for treatment A (see 3.1) 7.1.1 alkaline solution Vapour degreasing, solvent cleaning or alkaline cleaning with a non-etching, non-silicated hot 7.1.2 Water rinsing and check for water break, repeat cleaning if break occur
25、s 7.2 Cleaning for treatments B, C, D (see 3.2, 3.3 and 3.4) 7.2.1 Heavily soiled parts shall be emulsion cleaned, vapour degreased or solvent cleaned. 7.2.2 If there is a natural oxide film, carry out abrasive blasting or chemical deoxidizing. When pickling does not follow immediately after these o
26、perations, the parts shall be vapour degreased or cleaned with a hot alkaline solution. 7.2.3 If there is no significant natural oxide film, parts shall be cleaned with a hot alkaline solution. The alkaline solution shall be corrosion inhibited and preferably of a non-silicated type. For the parts t
27、o be bonded a non-silicated alkaline solution is mandatory. After alkaline cleaning, the parts shall be thoroughly water rinsed and inspected for water break. Cleaning shall be repeated if break occurs. STD-BSI BS EN 2334-ENGL L997 Lb24bbS b59454 T36 Page 5 EN 2334 : 1997 8 Treatment Immediately aft
28、er final cleaning, the pans shall be pickled in one of the solutions specified in annex A. To ensure a well pickled surface, the following shall be observed : - excessive bath loading and shielding of parts by each other shall be avoided ; - to ensure satisfactory adhesion and durability properties
29、for treatments A and B or to obtain a satisfactory metal removal rate, pure aluminium and certain aluminium alloys with a very low copper content at the surface (clad aluminium alloys, AI-Mg alloys) require additional provisions. The parts in these materials shall be either suspended on supporting j
30、igs which shall be more noble (cathodic) relative to the materials to be treated, e.g. unclad AI-CU alloy, or coupled to auxiliary cathodes. The position of the parts (anodes) relative to the cathodic areas and the cathodic to anodic area ratio shall be chosen carefully. Electrical contacts at sever
31、al points shall be provided. 9 Post-treatments 9.1 Rinsing It shall be carried out as quickly as possible after pickling in running water with a temperature not exceeding 40 OC. The water used for final rinsing shall have a conductivity not more than 70 pS/cm. 9.2 Drying The parts shall be dried exc
32、ept for those submitted for subsequent chemical or anodic treatment. The temperature shall be I65 OC. The dry parts shall be protected against contamination. 9.3 Treatment after drying As the adhesives and primers shall be applied within 16 h of drying for treatment B and within 4 h for treatment A,
33、 necessary measures shall be taken. Moreover, it shall be ensured that the treated parts are stored under clean, dry conditions. 10 Required characteristics and inspection 10.1 Parts 10.1.1 Cleanliness No water break shall be observed when the surface is wetted with clean water (max. temperature 35
34、OC) by immersion or spray. This operation has to be carried out after final rinsing. Page 6 EN 2334 : 1997 1 O. 1.2 Appearance When subjected to visual inspection, the pickled surfaces shall be of a homogeneous appearance and free from pitting, stains and contamination. 10.2 Process 10.2.1 Air used
35、for drying or other operations shall be dry and free from oil. 10.2.2 Mercury or mercury compounds shall not be present in any of the materials used. 10.2.3 Chemical analyses of the pickling solutions shall be carried out at regular intervals to determine the content of Cr6+, free acid, chloride, ir
36、on, copper, aluminium and, when requested, the Cr3* content to ensure that the composition is maintained within the limits specified in annex A. 10.2.4 The purity of the rinsing water shall be determined by conductivity measurements. 10.2.5 When required for adhesive bonding, the test to the relevan
37、t bonding standard shall be carried out to ensure that the process has been correctly applied, 11 Quality assurance 1 1.1 See EN 2000. Approval of the processor 1 1.2 Process approval The processor shall carry out : - pickling on a series of test pieces or pre-production parts agreed between the pur
38、chaser and processor ; - the tests specified in this standard, unless otherwise agreed between the purchaser and processor. When the test results have been accepted as satisfactory by the purchaser, he shall give his written approval to start production. The procedure shall not be changed without pr
39、evious agreement from the purchaser. 1 1.3 Acceptance After pickling, the parts shall have the required characteristics according to 1 O. The frequency and nature of the inspection shall be specified in the design documents or agreed between processor and purchaser. Parts not meeting the requirement
40、s shall be rejected. Parts which develop water break shall be reprocessed. 12 Health, safety and environmental aspects The locally applicable regulations and laws shall be observed. STD-BSI BS EN 233Li-ENGL L977 = lb24bb9 Ob5945b 809 Page 7 EN 2334 : 1997 13 Designation EXAMPLE : EN2334A Treatment (
41、see 3) A STDmBSI BS EN 2334-ENGL 1997 = Lb24bb9 Ob59Y57 745 Page 8 EN 2334 : 1997 Annex A (normative) Table Al : Pickling solutions Pickling solutions Chromic acid (CrOJ Free culphuric acid (H2S041 Water Chloride (as NaCI) Aluminium Copper Iron Temperature Immersion time Sodium dichromate (NazCr207
42、. 2Hz0) Free sulphuric (H2S04) Water 2) Chloride (as NaCI) Aluminium 3) Copper 3) Iron Temperature Immersion time Application to treatment A and B I C and D 45 g/l to 55 g/l 220 g/l to 300 g/l Remainder 0,2 g/l max. 1,5 g/l min. 0,06 g/I to 1 g/l 1 g/l max. 60 OC to 65 OC 28 min to 30 min 11 4) 5) 3
43、0 g/l to 55 g/l 150 g/l to 300 g/l Remainder 0,2 g/l max. 1 g/l max. 1 g/l max. 60 OC to 65 OC 20 min to 30 min 1) 41 5) 67 g/l to 83 g/l 220 g/l to 300 g/l Remainder 0,2 g/l max. 1,5 g/l min. 0,06 g/l to 1 g/l 1 g/l max. 60 OC to 65 OC 28 min to 30 min 6) 4) 5) 45 g/l to 83 g/l 150 g/l to 300 g/l R
44、emainder 0,2 g/l max. 1 g/l max. 1 g/l max. 60 OC to 65 OC 20 min to 30 min 6) 4) 5) 2) The solutions shall be prepared and maintained at the operating level with water having a conductivity I 1 O0 pS/cm and checked at regular intervals to ensure conformance with the tolerances specified for the com
45、position. 3) To reach the required minimum aluminium and copper content, a fresh solution shall be either aged with AI-CU unclad alloy chips or mixed with a part of an old pickling or anodizing solution. As an alternative, copper sulphate may be added to reach the required minimum copper content. 4)
46、 The solution may be operated at 65 OC to 70 OC. In this case, the treatment time shall be 15 min to 25 min. 5) Parts machined all over which are not to be bonded, may be pickled for less than 20 min. 6) H2S0, : (2,5 to 3.5 x Na2Cr20,. 2H,O) The solutions shall be discarded when pitting of parts occ
47、urs or when solid material starts to precipitate on cooling the solution to ambient temperature. The latter depends on the combined effect of dissolved metal and free acid content and can be expected at an aluminium content above 14 g/l. BS EN 2334 : 1997 BSI 389 Chiswick High Road London w4 4AL - S
48、TD-BSI BS EN 2334-ENGL 1997 lb24bb7 b59458 bBL = BSI - British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Contract requirem
49、ents A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Revisions British Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of t
