1、EUROPEAN STANDARD EN 2101 NORME EUROPENNE EUROPISCHE NORM July 1991 UDC : 669.71 5.691.51546.766-32:629.7 Key words : Aircraft industry, aluminium, aluminium alloys, rolled products, anodizing, chromic acid, setting- up conditions, quality assurance, corrosion resistance, inspection. English version
2、 Aerospace series Chromic acid anodizing of aluminium and wrought aluminium alloys 1 Srie arospatiale Luft- und Raumfahrt von Aluminium und . Anodisation chromique C hromsaure- Anodicieren alliages da luminium corroys Aluminium-Knetlegierungen de laluminium et des This European Standard was accepted
3、 by CEN on 1990-06-28. CEN members are bound to comply with the requirements of CEN Internal Regulations which stipulate the conditionsfor giving this European Standard the status of a national standardwithout any alteration. Up-to-date lists and bibliographical references concerning such national s
4、tandards 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). A version in any other language made by translation under the responsibility of a CEN member into its own language and noti
5、fied to CEN Central Secretariat has the came 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, Spain, Sweden, Switzerland and United
6、Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat : Rue de Stassart, 36, B-1 O50 Bruxelles _p CEN 1991 Copyright reserved to all CEN members Ref. Nr EN 2101 : 1991 E a- 0 CEN EN*ZLOL 91 W 3404589 0035328 3 mi Content
7、s Scope and field of application Purpose of anodizing References Material categories Supporting jig Processing sequence Quality assurance Designation r: 4 4 4 5 5 5 7 ie Annex A - Surface preparation recommendations 11 Annex B - Inspection of the absorbing ability by anthraquinone 13 violet drop tes
8、t Annex C - Inspection of corrosion resistance by repeated 14 immersion test in salt solution - - . .,y, Page 3 EN 2101:1991 This European Standard has been prepared by the European Association of Aerospace Manufacturers ( AEC MA) e 6- After inquiries and votes carried out in accordance with the rul
9、es 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 GEN. According to the Common CEN/CENELEC Rules, the following countries are bound to implement this Europ
10、eanStandacd: Austria, BelGun, Damark, Finland, France, Gemmy, c;reece, ce land, rel land, Italy, Luxerg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and Mted Kingdan. - CEN EN*2101 92 3909589 0035330 3 ml Page 4 EN 2101:1991 I 1 Scope and field of application This standard specifies th
11、e 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 aerospace construction when reference is mad
12、e 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 It is intended for corrosion protection. I
13、t shall be with or without colouring and used with or without additional painting. i . Type B : Sealed anodizing 3 References IS0 1463-1 982 IS0 2085-1 976 IS0 2106-1 982 IS0 21 43-1 981 IS0 2360-1 982 IS0 2376-1 972 IS0 3768-1 976 EN 2334 Metallic and oxide coatings - Measurement of coating thickne
14、ss - Microscopical method Anodizing of aluminium and its alloys - Check of continuity of thin anodic oxide coatings - Copper sulphate test Anodizing of aluminium and its alloys - Determination of mass per unit area (surface density) of anodic oxide coatings - Gravimetric method Anodizing of aluminiu
15、m and its alloys - Estimation of loss of absorptivepower of anodic oxide coatings after sealing - Dye spot test with prior acid treatment - Non-conductive coatings on non-magnetic basis metals - Measurement of coating thickness - Eddy current method Anodization (anodic oxidation) of aluminium and it
16、s alloys - Insulation check by measurement of breakdown potential .- Metallic coatings - Neutral salt spray test (NSS test) Aerospace series - Acid chromate pickle for aluminium alloys 1). _ - - 1) In preparation at the date of publication of this standard. _ _. . . . . - 4 Material categories 4.1 C
17、ategory 1 Pure aluminium, clad alloys, alloys characterised by the absence of copper or with a copper content limited to 1 %. r?. 4.2 Categoly2 Non-clad alloys containing 1 % copper : _ - - - . . - Category 2 A : solution heat treated, quenched and naturally aged condition - Category 2 B : solution
18、heat treated, quenched plus artificially aged condition. 5 Supporting jig The supporting 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 se
19、quence 6.1 Cleaning (see annex A) The cleaning methodused shall be appropriate for the contamination experienced on the materials treated. Solvent degreasing followed by cleaning in an alkaline bath is generally the most effective method. 6.2 Pickling (see annex A) The pickling operation shall remov
20、e natural oxides in order to obtain correct anodizing; it shall neither dearade 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 con
21、ducted in a sulphuric-chromic acid bath, but in exceptional cases, for certain alloys of category 2, alkaline pickling may be used. I. CEN EN*ZI,OI, m 4015 001,5332 5 mI Page 6 EN 2101:1991 - Chlorides : 200 mg/l expressed as NaCI, - Sulphates : 500 mg/l expressed as H2SO4. I The chromic acid anodiz
22、ing bath shall be made up with deionized water of a resistivity of more than 105 n.cm unless sufficiently pure ordinary water is available. 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 s
23、pray. It is recommended that rinsing in ordinary water is followed by rinsing in deionized or distilled water. I 6.4 Anodizing + The control system shall make it possible to maintain the treatment temperature within a tolerance of f 2 OC in a suitably agitated bath. 6.4.1 Electrolyte Aqueous solutio
24、n of chromic acid(99,5 % min, Cros) at a concentration of 30 g/l to 150 g/l to which certain additional agents such as oxalic acid may be added. 6.4.2 Treatment conditions The anodizing parameters (temperature, voltage, time) shall be adapted to the material and its category in accordance with the b
25、ath composition. NOTE : The treatment 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. Page 7 EN 2101:1991 6.6 Sealed anodizing The
26、 sealing quality stipulated in this standard requires the use of water having a resistivity greater than 105 R.cm when made up. The pH shall be between 53 and 6.9. The temperature of the sealing bath shall not be less than 97 OC. . For alloys of category 2, sealing shall preferably be applied with t
27、he addition in deionized water of not less than 30 mg/l potassium dichromate, with a resistivity greater than 105 Rxm. 6. 6.7 The method used to remove the anodic coating shall be such that, when reanodized, the dimensions and surface roughness shall conform with the values specified. Removal of the
28、 anodic coating (see annex A) I 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 qualification of a new installation
29、 and for continuous quality monitoring : 7.1 .I Chemical analysis of the bath on make up and during operation (see clause 6.4.1), 7.1.2 Measurement of resistivity and pH of the sealing bath (see clause 6.6). - i; CEN EN*ZLOL 91 W 3404589 0035335 O II Page 9 EN 2101:1991 _- - - 3 3 r L W U I E O O ln
30、 U 4-0 WE 83i E O v, y. O I . . _-_.- . . - . .A , . -. CEN EN*2303 93 3404589 0035336 2 =I Page 10 EN 2101:1991 Description block CHROMIC ACID ANODIZING 7.3 Test report Identity block EN21 O1 A The test report shall state the following : - Reference to this standard - Type of anodizing (type A or 6
31、) - Category of the material and its heat treatment - Batch number - Test results, - Date of anodizing 6. 8 Designation The following designation shall be indicated on the relevant documents : NOTE : If necessary, the originator code 19005 may be introduced between the description block and the iden
32、tity block. -. _ .I . -. . . . . Page 11 EN 2101:1991 A.1 Scope Annex A Surface preparation recommendations - 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
33、 solvents a) Hot solvents non-water washable Halogenated hydrocarbons in the liquid or vapour phase such as trichlorethyleve, perchlorethylene, trichlorotrifluoroethane and 1-1 -1 trichloroethane. b) Cold solvents non-water washable Sovents in the liquid phase such as those listed under a) and white
34、 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
35、 degreasing. The degreasing baths used shall be inhibited to avoid attack of metal surfaces. They may be used hot or cold with or without electrical current. A,3 Cleaning by abrasive blasting A.3.1 Rough cleaning Blasting abrasives of a grit size of more than 100 bm with or without water. This clean
36、ing is not applicable to thin parts or when the required surface roughness does not allow it. . . i . Pace 12 EN 2101:1991 A.3.2 Fine cleaning Blasting of abrasives of a grit size of less than or equal to 1 O0 ,um with or without water. A.4 Pickling A.4.1 Acid A.4.1.1 Sulphuric-chromic acid Parts sh
37、all be processed in accordance with EN 2334. A.4.1.2 Other baths Baths containing e.g, fluorides may be used. i A.4.2 Alkaline Bath composition : - Sodium hydroxide : 26 g/l to 50 g/l - Sodium heptonate or gluconate : 0,75 g/l to 1 ,O g/l Conditions of use : - Temperature - Rate of attack : 40 OC to
38、 65 OC. : 0,6 pm/min to 1,5 pm/min. The reaction is very vigorous and an immersion time of 15 s to 1 min is generally sufficient. This bath is not applicable to close tolerance parts, nor to assemblies joined by riveting or resistance welding or if a surface polish is required. A.4.3 De-smutting The
39、 deposit formed after alkaline pickling and certain acid pickling operations is eliminated by immersion in a aqueous solution of 30% to 50% by volume of nitric acid ( p20 OC = 1,4 g/cm3) at room temperature. A.5 Stripping of anodic coatings The following aqueous solution may be used at a temperature
40、 of 97 OC to 100 OC : - Phosphoric acid (85% by mass) - Chromic acid : 20 g/l to 25 g/l : 25 ml/l to 35 ml/l Page 13 EN 2101:1991 Annex B Inspection of the absorbing ability by anthraquinone violet drop test B.1 Scope 6. This annex describes the method of inspection of the absorbing ability of the o
41、xide films obtained by anodizing by anthraquinone violet drop test. 8.2 Field of application This method is applicable to all sealed oxide coatings produced on wrought aluminium and aluminium alloys. As the estimation is based on the persistence of a colouration, the method cannot apply to dyed coat
42、ings of dark shades such as : deep black, deep blue, deep purple. 8.3 Equipment No special equipment, B,4 Operation method A given surface of the anodized specimen is carefully degreased with a suitable solvent (e.g. benzol, trichloroethylene) and if necessary with a light abrasive (e,g. magnesia pa
43、ste diuted in water) so as to obtain complete cleaning of the surface. - - - -_. - .-._ . .- -_ _- _. . . . A few drops of a 1 % anthraquinone violet solution are deposited on an area of about 1 cm* of the surface prepared in this way, .- It is left to act for 5 min. The surface is cleaned by rubbin
44、g, under running water, using a cotton swab or light abrasive (magnesia, pearl white) for 2 min, and then in a neutral soap solution, It is thoroughly rinsed and dried, 8.5 Interpretation of results If no residual indelible stain on the tested area persists, the coating has lost its absorptive power
45、 and this indicates a correctly sealed coating. .- Page 14 EN 2101:1991 Annex C Inspection of corrosion resistance by repeated immersion test in salt solution C.l Scope and field of application i!. This annex specifies the method of inspection of corrosion resistance of the sealed oxide films obtain
46、ed by anodizing by repeated immersion tests in salt solution. C.2 Salt solution (Reagent) This consists of a 30 g/l sodium chloride solution in distilled or deionized water to which-a buffer - - . . ._ mixture of : _ “- . - Chemically pure disodium phosphate : 0,19 g - Boric acid : 1,25 g is added.
47、To produce a pH value of approximately 8, add a quantity of saturated sodium carbonate solution in distilled water. The necessary quantity of this solution can be determined either with the pH-meter or on an aliquot portion poured into a test tube rinsed several times with the reagent, to which 0,5
48、ml phenolphtalein is added per 1 O ml reagent; it is obtained when the solution takes on a pink colouration. Page 15 EN 2101:1991 C.3 Equipment The equipment consists of an oven maintained throughout at a temperature of between 33 OC and 37 OC with a humidity of 80% to 95% containing the following :
49、 - An appropriate Set-up by which the complete operations of alternating immersion and removal can be obtained automatically and continuouslyfor each part or specimen attached to this Set-up by clamps made from insulating material. . - One or several glass or plastic containers holding the reagent. C,4 Operating method (2.4.1 The specimens defined in clause 7.1.3 of this standard or the parts are carefully degreased with a volatile solvent vapour according to the conditions of annex A, clause A.2.1, a). Preparation of the surfaces to
