1、CEN EN*Z2B4 93 3404589 0035342 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 2284 July 1991 UDC : 669.71 5.691.5t546.226-325629.7 $- Key words : Aircraft industry, aluminium, aluminium alloys, rolled products, anodizing, sulphuric acid, setting- up conditions, quality assurance, corrosion res
2、istance, inspection. English version Aerospace series Sulphuric acid anodizing of aluminium and wrought aluminium aiioys Srie arospatiale Luft- und Raumfahrt Anodisation sulfurique de !aluminium et des alliages daluminium corroys Schwefelsure- Anodisieren von Aluminium und Aluminium-Knetlegierungen
3、This European Standard was accepted by CEN on 1990-06-28. CEN members are bound to comply with the requirements of CEN Internal Regulations which stipulate the conditionsfor givingthis European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical re
4、ferences concerning such national standards may be obtained on application to the CEN Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). Aversion in any other language made by translation under the responsibility of a CEN mem
5、ber into its own language and notified to CEN Central Secretariat has the same status as the official versions. CEN members are the national standards organizations of Austria, Belgium,. Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxemburg, Netherlands, Norway, Portugal. Spa
6、in, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit EuropBen de Normalisation Europisches Komitee fr Normung Central Secretariat : Rue de Stassart, 36, 8-1 050 Bruxelles . CEN 1991 Copyright reserved to ali CEN members Contents 6. 1 2 Purpose of anodizing 3 R
7、eferences 4 Material categories 5 Supporting jig 6 Processing sequence 7 Quality assurance 8 Designation Scope and field of application 4 4 4 5 5 8 10 Page 3 EN 2284:1991 This European Standard has been prepared by the European Association of Aerospace Manufacturers (AECMA). After inquiries and vote
8、s carried out in accordance with the rules of this Association, this Standard has successively 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 cou
9、ntries are bound to implement this European Standard: Austria, Belgiun, Derrrrark, Finland, France, Gerarany, Gree, ce land, Ireland, Italy, LuxCrribourg, Netherlands, Nonay, Portugal, spuin, sreda, Sritzerland and mtd Kingdon. 1 CEN EN*Z284 91 3404589 0035345 3 =I _. _- Page 4 EN 2284:1991 1 This s
10、tandard 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 applies to parts in aluminium and wrought aluminium alloys of category 1 and 2 (see clause 4) used in aerospace construction
11、 when reference is made to this standard. Scope and field of application 6. 2 Purpose of anodizing 2.1 It shall be used either as surface preparation before the application of paint or any other finish. Type A : Unsealed anodizing 2.2 It is intended for corrosion protection. It shall be with or with
12、out colouring and used with or without a ddi t iona I pa inti ng . Type B : Sealed anodizing NOTE : Sulphuric acid anodizing diminishes the fatigue characteristics of the parts; therefore its application shall be avoided for parts subject to high fatigue stress. 3 References IS0 1463-1 982 IS0 2085-
13、1 976 IS0 21 06-1 982 IS0 2143-1 981 982 972 IS0 2360- IS0 2376- Metallic and oxide coatings - Measurement of coating thickness - Microscopical method Anodizing of aluminium and itsalloys - Checkof continuityof thin anodicoxide coatings - Copper sulphate test Anodizing of aluminium and its alloys -
14、Determination of mass per unit area (surface density) of anodic oxide coatings - Gravimetric method 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 Non-conductive coatings on non-magne
15、tic basis metais - Measurement of coating thickness - Eddy current method Anodization (anodic oxidation) of aluminium and its alloys - Insulation check by measurement of breakdown potential Page 5 EN 2284:1991 IS0 3768-1 976 Metallic coatings - Neutral salt spray test (NSS test) EN 2101 EN 2334 Aero
16、space series - Chromic acid anodizing of aluminium and wrought aluminium alloys Aerospace series - Acid chromate pickle for aluminium alloys 1). 4 Material categories 4.1 Category 1 Pure aluminium, clad alloys, alloys characterised by the absence of copper or with a copper content limited to 1 %* 4.
17、2 Category2 Non-clad alloys containing 1 % copper (classified only according to their heat trehtment condition) : - 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 supp
18、orting jig (e.g. in aluminium alloy or titanium) shall provide effective electrical contact with the parts, This contact is preferably achieved at several points in order to ensure better current distribution. 6 Processing sequence 6.1 Cleaning (see EN 2101, annex A) The cleaning method usedshall be
19、 appropriate for the contamination experienced on the materials treated. Solvent degreasing followed by cleaning in an alkaline bath is generally the most effective method. ) In preparation at the date of publication of this standard, CEN EN8K228Li 93 II 3404589 0035347 7 W e , Page 6 EN 2284:1991 6
20、.2 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 specified.
21、 As a general rule, pickling is conducted in a sulphuric/$hromic acid bath, but in exceptional cases, for certain alloys of category 2, alkaline pickling may be used. Pickling (see EN 2101, annex A) 6.3 Rinsing All rinsing operations before anodizing shall be effective and complete. For example, the
22、y may be performed by immersion 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 (p 20%= 1,84g/cm3) at a concentration of 9Og/l to 400 g/l, to w
23、hich additional agents can be added, with the agreement of the quality assurance authority. The impurity content shall be less than chloride : 200 mg/l expressed as NaCI. The sulphuric acid anodizing bath shall be made up with deionised water of a resistivity of more than lo5 n.cm, unless sufficient
24、ly pure ordinary water is available. 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
25、tolerance of f 2 OC in a suitably agitated bath. NOTE : The treatment of materials of different categories in one anodizing batch shall be avoided. Page 7 EN 2284:1991 6.4.3 Unsealed anodizing In this case, it is necessary to take great precautions to avoid contamination of the oxide coating during
26、handling. If a paint finish is required it shall be applied as soon as possible and 16 h max. after anodizing. 6.4.4 Coloured anodizing If required any colouring of the partsshall be carried out immediatelyafter anodizing and careful rinsing. It is carried out in an aqueous solution in accordance wi
27、th the conditions (concentration, pH, time, temperature, etc.) given 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 lecc than 50 OC shall be carried out, 6.45 Sealed anodizing On coloured piece
28、s, sealing is performed in pure water, or in pure water to which has been 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. i 6.4.6.1 Sealing in pure wat
29、er The quality of sealing required by this standard necessitates the use of water of a resistivity of more than 1 O5 R.cm when made up. The pH shall be between 5,5 and 6,9. The bath temperature shall be no less than 97 OC, The sealing bath shall be renewed when the resistivity is 105 fl .cm. 6.4.5.2
30、 Sealing with addition of an inhibitor In this case, 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 than 97 OC and the pH shall be between 5,5 and 63. The inhibitor conce
31、ntration shall be established and maintained within limits which ensure the quality specified by this standard. 6.5 Removal of the anodic coating (see EN 21 01. annex A) .-. - The method used to remove the anodic coating shall be such that, when reanodised, the dimensions and surface roughness shall
32、 conform with the values specified. r -A CEN EN*Z284 71 3404589 0035347 O Page 8 EN 2284:1991 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 6 The following
33、tests shall be conducted for qualification 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). 7.1.2 Measurements of resistivity and pH of the sealing bath (see clause 6.4.5). 7.1.3 Corrosion tests Thes
34、e tests (see table) are applicable to anodized and sealed pans only. . . Not less than 5 rectangular specimens of the minimum dimensions of 60 mm X 120 mm, thickness optional, representative of the treated parts (material, heat treatment, surface finish) shall be anodized and sealed. If it is imposs
35、ible to produce rectangular specimens, the surface exposed to corrosion for each specimen shall be practically equivalent. 7.1.4 discretion of the quality assurance Authority. The frequency of the inspection of bath efficiency is laid down by the official services or at the 7.2 Inspection of treated
36、 parts Where it is not practicable 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 at the same time shall be used. 7.2.1 Batching A batch consists of all parts treated at the same time in
37、 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 subjected to individual inspection. NOTE : A maximum thickness may be specified on the drawing for special cases, e.g. parts subject to high fatigue stress, rivet
38、s, etc. - - - CEN EN*E!284 93 3404589 0035350 7 m Page 9 EN 2284:1991 - O O In N P I (o c, v) al O z c, In rl CS( I c c O o u) v) u) Q) C -ic o .- Y L c .- L g is c1 S O 5 m - S o m P O C lu 9) = .- Y L E E 5 8 2 L .w $ o v) m v) lu v) v) m .- c, 4- c In CS( cv I c 8 n u) .E B . sg u) Q n L ! l CEN
39、EN*Z284 91 3404589 0015351 9 -1 O? Description block SULPHURIC ACID ANODIZING Page 10 EN 2284:1991 Identity block EN2284AC 7.3 Test report The test report shall indicate the following : - Reference to this standard - Type of anodizing (A or B), with or without colouring - Category of the material and heat treatment - Date of anodizing - Batch number - Test results. Type of anodizing (see clause a- 2) Number of EN standard Code C, when colouring is required ,
