1、BRITISH STANDARD AEROSPACE SERIES BS EN 2334:1997 Chromic-sulphuric acid pickle of aluminium and aluminium alloys The European Standard EN2334:1997 has the status of a British Standard ICS 49.040BSEN2334:1997 This British Standard, having been prepared under the directionof the Engineering SectorBoa
2、rd, was published underthe authority of the Standards Board and comesintoeffect on 15November1997 BSI 04-2000 ISBN 0 580 28135 3 National foreword This British Standard is the English language version of EN2334:1997. The UK participation in its preparation was entrusted to Technical Committee ACE/44
3、, 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 proposals for change, and keep the UK interests informed; monitor related international and Euro
4、pean 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 European publications referred to in this document may be found in the BSI Stand
5、ards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. NOTEUnder the AECMA part numbering system, normative references to the Parts of AECMA-originated European Standards may appear in claus
6、e2 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 three-digit and single digit forms can be used interchangeably. For the purposes of part-marking of components produced in accordance with this standard
7、, the three-digit form should be used. 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. Compliance with a British Standard does not of itself confer immunity from legal obligations. Su
8、mmary of pages This document comprises a front cover, an inside front cover, pages i and ii, theEN title page, pages 2 to 6 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside fron
9、t cover. Amendments issued since publication Amd. No. Date CommentsBSEN2334:1997 BSI 04-2000 i Contents Page National foreword Inside front cover Foreword 2 Text of EN 2334 3ii blankEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 2334 July 1997 ICS 49.040.40 Descriptors: Aircraft industry, alum
10、inium, aluminium alloys, cleaning English version Aerospace series Chromic-sulphuric acid pickle ofaluminium and aluminium alloys Srie arospatiale Dcapage sulfochromique de laluminium et des alliages daluminium Luft- und Raumfahrt Beizen von Aluminium und Aluminiumlegierungen in Chromschwefelsure Th
11、is European Standard was approved by CEN on1996-08-04. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
12、concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. The 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
13、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, CzechRepublic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, S
14、weden, 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 1997 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national
15、 Members. Ref. No. EN 2334:1997 EEN2334:1997 BSI 04-2000 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 received the approval
16、 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 the latest by January1998, and conflic
17、ting national standards shall be withdrawn at the latest by January1998. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, CzechRepublic, Denmark, Finland, France, German
18、y, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the UnitedKingdom. Contents Page Foreword 2 1 Scope 3 2 Normative references 3 3 Purpose of process 3 4 Information for the processor 3 5 Condition of parts prior to processing 3 6 Process s
19、chedule 3 7 Pre-treatments 4 8 Treatment 4 9 Post-treatments 4 10 Required characteristics and inspection 4 11 Quality assurance 5 12 Health, safety and environmental aspects 5 13 Designation 5 Annex A (normative) 6 Table 1 3 Table A.1 Pickling solutions 6EN2334:1997 BSI 04-2000 3 1 Scope This stand
20、ard specifies the acid chromate pickling of aluminium and aluminium alloys except those with a silicon content in excess of2% 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
21、 from other publications. These normative 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 ame
22、ndment or revision. For undated references 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 Reference surface treatment, e.g.prior to adhesive bonding
23、 or primer application to test specimens used for qualification and acceptance tests on adhesives, paints, sealants (treatment A) 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 Pr
24、e-treatment (treatment D) for: anodizing for other applications than adhesive bonding; other chemical treatments. 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 Con
25、dition of parts prior to processing Fabrication of the parts shall have been completed before pickling. 6 Process schedule The pickling process shall be performed according to Table 1. Table 1 Process schedule Application, see treatment A B C D Pre-treatments 7.1 7.2 7.2 7.2 Pickling 8 8 8 8 Post-tr
26、eatments 9.1 9.1 9.1 9.1 9.2 9.2 9.3 9.3EN2334:1997 4 BSI 04-2000 7 Pre-treatments 7.1 Cleaning for treatment A (see 3.1) 7.1.1 Vapour degreasing, solvent cleaning or alkaline cleaning with a non-etching, non-silicated hot alkaline solution. 7.1.2 Water rinsing and check for water break, repeat clea
27、ning if break occurs. 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 immed
28、iately after these operations, 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 t
29、ype. For the parts to 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. 8 Treatment Immediately after final cleaning, the parts shall be pickled in o
30、ne 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 for treatments A and B or to obtain a satisfactory meta
31、l removal rate, pure aluminium and certain aluminium alloys with a very low copper content at the surface (clad aluminium alloys, Al-Mg alloys) require additional provisions. The parts in these materials shall be either suspended on supporting jigs which shall be more noble (cathodic) relative to th
32、e materials to be treated, e.g.unclad Al-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 several points shall be provided. 9 Post-treatments 9.1 Rinsi
33、ng It shall be carried out as quickly as possible after pickling in running water with a temperature not exceeding40 C. The water used for final rinsing shall have a conductivity not more than 704S/cm. 9.2 Drying The parts shall be dried except for those submitted for subsequent chemical or anodic t
34、reatment. The temperature shall be k 65 C. The dry parts shall be protected against contamination. 9.3 Treatment after drying As the adhesives and primers shall be applied within16h of drying for treatment B and within4h for treatment A, necessary measures shall be taken. Moreover, it shall be ensur
35、ed 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 C) by immersion or spray. This operation has to be carried out
36、after final rinsing. 10.1.2 Appearance When subjected to visual inspection, the pickled surfaces shall be of a homogeneous appearance and free from pitting, stains and contamination.EN2334:1997 BSI 04-2000 5 10.2 Process 10.2.1 Air used for drying or other operations shall be dry and free from oil.
37、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 Cr 6+ , free acid, chloride, iron, copper, aluminium and, when requested, the Cr 3+content t
38、o 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 relevant bonding standard shall be carried out to ensure that the pr
39、ocess has been correctly applied. 11 Quality assurance 11.1 Approval of the processor See EN 2000. 11.2 Process approval The processor shall carry out: pickling on a series of test pieces or pre-production parts agreed between the purchaser and processor; the tests specified in this standard, unless
40、 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 previous agreement from the purchaser. 11.3 Acceptance After pickling,
41、the parts shall have the required characteristics according to 10. The frequency and nature of the inspection shall be specified in the design documents or agreed between processor and purchaser. Parts not meeting the requirements shall be rejected. Parts which develop water break shall be reprocess
42、ed. 12 Health, safety and environmental aspects The locally applicable regulations and laws shall be observed. 13 Designation EXAMPLE:EN2334:1997 6 BSI 04-2000 Annex A (normative) Table A.1 Pickling solutions The solutions shall be discarded when pitting of parts occurs or when solid material starts
43、 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 14g/l. Pickling solutions Application to treatment A and B C and D Chromic acid (CrO 3 ) 45 g/l to 55 g
44、/l 30 g/l to 55 g/l Free sulphuric acid (H 2 SO 4 ) 220 g/l to 300 g/l a 150 g/l to 300 g/l a Water b Remainder Remainder Chloride (as NaCl) 0,2 g/l max. 0,2 g/l max. Aluminium c 1,5 g/l min. Copper c 0,06 g/l to 1 g/l 1 g/l max. Iron 1 g/l max. 1 g/l max. Temperature 60 C to 65 C d 60 C to 65 C d I
45、mmersion time 28 min to 30 min e 20 min to 30 min e Sodium dichromate (Na 2 Cr 2 O 7 .2H 2 O) 67 g/l to 83 g/l 45 g/l to 83 g/l Free sulphuric (H 2 SO 4 ) 220 g/l to 300 g/l f 150 g/l to 300 g/l f Water b Remainder Remainder Chloride (as NaCl) 0,2 g/l max. 0,2 g/l max. Aluminium c 1,5 g/l min. Coppe
46、r c 0,06 g/l to 1 g/l 1 g/l max. Iron 1 g/l max. 1 g/l max. Temperature 60 C to 65 C d 60 C to 65 C d Immersion time 28 min to 30 min e 20 min to 30 min e a H 2 SO 4 : (4,5 to 5,5 CrO 3 ) b The solutions shall be prepared and maintained at the operating level with water having a conductivity k 100 4
47、S/cm and checked at regular intervals to ensure conformance with the tolerances specified for the composition. c To reach the required minimum aluminium and copper content, a fresh solution shall be either aged with Al-Cu unclad alloy chips or mixed with a part of an old pickling or anodizing soluti
48、on. As an alternative, copper sulphate may be added to reach the required minimum copper content. d The solution may be operated at 65 C to 70 C. In this case, the treatment time shall be 15 min to 25 min. e Parts machined all over which are not to be bonded, may be pickled for less than 20 min. f H
49、 2 SO 4 : (2,5 to 3,5 Na 2 Cr 2 O 7 .2H 2 O)blankBS EN 2334:1997 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions BritishStandards are updated by amendment or revision. Users of BritishStandards should make sure that they possess the latest amendments or editions
