1、AECMA PREN*3bb5 95 10123LL 00099bb 571 = Edition approved for publication 1995-1 1-30 AECMA STANDARD NORME AECMA AECMA NORM The equivalent versions in French and German languages can be supplied by B.N.A.E. - Technopolis 54 - 199, rue Jean-Jacques Rousseau 921 38 ISSY - LES - MOULINEAUX CEDEX - FRAN
2、CE prEN 3665 Edition 1 November 1995 PUBLISHED BY THE EUROPEAN ASSOCIATION OF AEROSPACE INDUSTRIES (AECMA) Gulledelle 94 - 6-1 200 BRUXELLES - Tel. (32) 2 775 81 1 O - Fax. (32) 2 775 81 11 ICs : 49.040.40 ENGLISH VERSION Aerospace series Test methods for paints and varnishes Filiform corrosion resi
3、stance test on aluminium alloys Srie arospatiale Luft- und Raumfahrt Mthodes dessai pour peintures et vernis Essai de rsistance la corrosion filiforme sur alliages daluminium Prfverfahren fr Anstrichstoffe Prfung der Bestndigkeit gegen Filiformkorrosion von Aluminiumlegierungen This “Aerospace serie
4、s“ Standard has been drawn up under the responsibility of AECMA (The European Association of Aerospace Industries). It is published on yell0 w paper in three equivalent versions (English, French, German). It will be submitted as a draft European Standard to CEN (European Committee for Standardizatio
5、n) for formal vote. - AECMA PREN*3665 95 10123361 O009968 344 Page 3 prEN 3665 : 1995 1 Scope This standard specifies a test method for determination of the protective action of coatings of paints or varnishes against filiform corrosion on aluminium alloys. 2 Normative references This European Stand
6、ard incorporates by dated or undated reference provisions 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 t
7、his European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN 2090 EN 2334 Aerospace series - Aluminium alloy 2024-T3 - Clad sheet and strip - 0,4 I a I 6 rnm 1) Aerospace series - Acid chromate pickl
8、ing of aluminium and aluminium alloys 2) 3 Definition For the purposes of this standard, the following definition applies : Filiform corrosion : A type of corrosion that occurs under coatings on metal substrates. It starts from unprotected edges or local damage through the coating. 4 Principle Coate
9、d metal test pieces are : - scribed ; - placed in a corrosive atmosphere to initiate corrosion ; - exposed to controlled temperature and humidity conditions conducive to filiform corrosion. 5 Apparatus and reagents - Tools for scribing grooves. - Container with cover, resistant to hydrochloric acid.
10、 - Test cabinet capable of being maintained at the required temperature and relative humidity. - Hydrochloric acid, analytical grade, p = 1,18 g/cm3. 6 Preparation of test pieces 6.1 General Unless otherwise specified, test pieces shall be in conformity with figure 1. 1) Published as AECMA Standard
11、at the date of publication of this standard 2) In preparation at the date of publication of this standard AECMA PREN*3bb5 95 LOL23LL 0009969 280 15 - F Page 4 prEN 3665 : 1995 - 50 - 15 - Test pieces shall be treated and coated as indicated in the paint and varnish standard. If the latter does not s
12、pecify any pretreatment, test pieces shall be acid chromate pickled in accordance with EN 2334 and coated with a paint primer within 4 h and subsequently with a finishing paint. After curing of the coating, grooves shall be scribed to 6.2. 6.2 Grooves Two grooves shall be made, see figures 1 and 2 o
13、r 3. The paint film at the groove edges shall be smooth. Dimension in millimetres - L 40 I 4 Rolling direction 40 2 Material : EN 2090 Thickness : 0,8 mm to 2 mm Figure 1 Page 5 prEN 3665 : 1995 6.2.1 Method A See figure 2. Dimensions in millimetres Figure 2 6.2.2 Method B See figure 3. Dimensions i
14、n millimetres 75“ * 2“ Figure 3 AECMA PRENS3665 95 m 3032333 0009973 939 m Page 6 prEN 3665 : 1995 7 Test procedure The container shall have (20 f 21 ml of hydrochloric acid per litre of volume. Place the test pieces in the container horizontally with the paint film downwards. The distance between t
15、est pieces and liquid level shall be (I00 f 101 mm. The distance between test pieces shall be 20 mm minimum. The container shall remain closed for (60 f 51 min at a temperature of (23 f 2) OC. After removal from the container the test pieces shall stand in open air for 15 min minimum and 30 min maxi
16、mum. Place the test pieces in a test cabinet at a temperature of (40 f 2) OC and (82 f 3) % relative humidity for the period time stated in the paint or varnish standard in an approximately vertical position. If specified, the coating shall be removed with a non corrosive paint remover within 6 h af
17、ter removal, at least in the deterioration area. Then, the test pieces shall be flushed with warm water and then again with alcohol. The test pieces shall be placed in a desiccator above a drying agent, until evaluation. 8 Eva1 uat i o n It shall be carried out using methods 1, 2 or 3 on the groove
18、with the highest degree of corrosion. 8.1 Method 1 This applies where there is regular corrosion, see figure 5. It includes : - measuring ML and MR, see figure 4, in order to calculate the maximum length M which is the mean value of ML and MR ; - measuring rn and rn, see figure 6, in order to calcul
19、ate the majority length rn which is the mean value of rn and rn . 8.2 Method 2 This applies where there is irregular corrosion. It includes : - determining M, see method 1 ; - measuring m1, m2, etc., in order to calculate the overall values rn and rn using the following formulae : XWLI + x2mL2 + x3m
20、L3 + x4mL4 Z mL = ylmR1 Y2mR2 + Y3mR3 i- Y4mR4 mR = Z where : rn1, rn1, XI, y1, etc. and Z are defined in figure 6. 8.3 Method 3 This applies in the case of regular and irregular corrosion. The degree of filiform corrosion is obtained by visually comparing the test piece with a series of standard ph
21、otographs. AECMA PRENx3bbS 95 1012321 0009972 875 Page 7 prEN 3665 : 1995 F k F c Figure 5 3 Figure 6 Page 8 prEN 3665 : 1995 9 Test report It shall include the following : - the designation, see 10 ; - the material and pretreatment of test piece ; - the identification of the paint or varnish batch, the application canditions ; - the degree of filiform corrosion ; - any deviation from this standard ; - the date of test. 10 Designation EXAMPLE: Method of scribing grooves (see 6.2) Number of this standard Evaluation method (see 8)
