ASD-STAN PREN 4704-2010 Aerospace series Tartaric-Sulphuric-Acid anodizing of aluminium and aluminium wrought alloys for corrosion protection and paint pre-treatment (TSA) (Edition.pdf

1、ASD-STAN STANDARD NORME ASD-STAN ASD-STAN NORM prEN 4704 Edition P 1 November 2010 PUBLISHED BY THE AEROSPACE AND DEFENCE INDUSTRIES ASSOCIATION OF EUROPE - STANDARDIZATIONAvenue de Tervuren, 270 - B-1150 Brussels - Tel. + 32 2 775 8126 - Fax. + 32 2 775 8131 - www.asd-stan.orgICS: Descriptors: ENGL

2、ISH VERSION Aerospace series Tartaric-Sulphuric-Acid anodizing of aluminium and aluminium wrought alloys for corrosion protection and paint pre-treatment (TSA) Srie arospatiale Anodisation tartrique de laluminium et des alliages daluminium corroys pour protection contre la corrosion et peinture (TSA

3、) Luft- und Raumfahrt Weinsure-Schwefelsure-Anodisieren (TSA) von Aluminium und Aluminium-Knetlegierungen fr den Korrosionsschutz und zur Vorbehandlung This “Aerospace Series“ Prestandard has been drawn up under the responsibility of ASD-STAN (The AeroSpace and Defence Industries Association of Euro

4、pe - Standardization). It is published for the needs of the European Aerospace Industry. It has been technically approved by the experts of the concerned Domain following member comments. Subsequent to the publication of this Prestandard, the technical content shall not be changed to an extent that

5、interchangeability is affected, physically or functionally, without re-identification of the standard. After examination and review by users and formal agreement of ASD-STAN, it will be submitted as a draft European Standard (prEN) to CEN (European Committee for Standardization) for formal vote and

6、transformation to full European Standard (EN). The CEN national members have then to implement the EN at national level by giving the EN the status of a national standard and by withdrawing any national standards conflicting with the EN. Edition approved for publication 1 November 2010 Comments shou

7、ld be sent within six months after the date of publication to ASD-STAN Metallic Material Domain Copyright 2010 by ASD-STAN prEN 4704:2010 (E) 2 Contents Page Foreword2 1 Scope 3 2 Normative references 3 3 Terms and definitions .4 4 Principle5 5 Requirements.5 6 Re-anodizing . 10 7 Qualification test

8、 report (QTR) 10 Annex A (informative) Whler curves an stress levels Reference fatigue curves . 11 Foreword This standard was reviewed by the Domain Technical Coordinator of ASD-STANs Metallic Material Domain. After inquiries and votes carried out in accordance with the rules of ASD-STAN defined in

9、ASD-STANs General Process Manual, this standard has received approval for Publication. prEN 4704:2010 (E) 3 1 Scope This standard defines the requirement for Tartaric-Sulphuric-Acid (TSA) anodizing of aluminium and wrought alloys for corrosion protection and paint pre-treatment. The purpose of this

10、standard is to give design and quality requirements to manufactures. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced do

11、cument (including any amendments) applies. EN 2101, Aerospace series Chromic acid anodizing of aluminium and wrought aluminium alloys EN 3665, Aerospace series Test methods for paints and varnishes Filiform corrosion resistance test on aluminium alloys EN 6072, Aerospace series Metallic materials Te

12、st methods Constant amplitude fatique testing 1)EN 12373-2, Aluminium and aluminium alloys Anodizing Part 2: Determination of mass per unit area (surface density) of anodic oxidation coatings Gravimetric method EN ISO 1463, Metallic and oxide coatings Measurement of coating thickness Microscopical m

13、ethod EN ISO 2360, Non-conductive coatings on non-magnetic electrically conductive basis materials Measurement of coating thickness Amplitude-sensitive eddy current method EN ISO 2409, Paints and varnishes Cross-cut test EN ISO 9227 Corrosion tests in artificial atmospheres Salt spray tests (ISO 922

14、7:2006) EN ISO 15528, Paints, varnishes and raw materials for paints and varnishes Sampling (ISO 15528:2000) 1) Published as ASD-STAN Prestandard at the date of publication of this standard by Aerospace and Defence Industries Association of Europe-Standardization (ASD-STAN), (www.asd-stan.org). prEN

15、 4704:2010 (E) 4 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 de-anodizing process, which removes the anodic oxide 3.2 smut precipitations of alloying elements (e. g. Cu, Fe, Zn, Si) on the surface of parts after a process step normally af

16、ter alkaline etching step 3.3 MDL mechanically disturbed layer layer that is present at the surface resulting from the rolling process of the material 3.4 pit surface corrosion defect at which the anodic coating is penetrated 3.5 process instruction document that describes the detailed process, para

17、meters, detailed steps, etc. 3.6 alloys all aluminium alloys, that are treated with the TSA process in the specific shop 3.7 re-anodizing repetition of the anodizing process step after complete de-anodizing 3.8 sealing sealing (of the anodized layers) is applied to close the pores produced by the ac

18、id anodizing process. It is usually applied in demineralized water bath. Sealing can improve the corrosion resistance performance of the anodic film. 3.9 dichromate sealing the dichromate sealing process has to be applied for unpainted parts It content one of the following products: Sodium dichromat

19、e Potassium dichromate It includes chromate and has to be replaced by a chromium III chemical conversion coating when available. prEN 4704:2010 (E) 5 4 Principle 4.1 General description of process TSA process is an electrochemical process used for generating an aluminium oxide layer for corrosion pr

20、otection and surface treatment prior to application of a corrosion-inhibiting primer. The TSA process is characterized by using an electrolyte composed of tartaric and sulphuric acid. Suitable surface preparation steps, e. g. alkaline cleaning, alkaline etching, acidic pickling/desmutting and subseq

21、uent steps such as rinsing (and sealing, if applicable), have to be defined and are integral to the TSA process. 4.2 Limitations All processes that can compromise the anodic film such as forming, or heat-treatment shall be performed prior to surface preparation of the parts to be anodized. TSA anodi

22、zing shall not be applied: for metal bonding applications; inside of oxygen pipes; for tubes, pipes and open holes with a length to diameter ratio higher than 10:1; for trapped holes with a length to a diameter ratio greater than 5:1; for parts or assemblies (e.g. spot-welded and riveted), which can

23、 permanently entrap; for components which can permanently entrap treatment solutions, except components that can be adequately masked. NOTE The formation of oxide layer influences the dimensions of the part and shall be considered for close tolerance parts. 5 Requirements 5.1 Technical requirements

24、5.1.1 Prior to anodizing step: the parts shall be free of oil, grease, marking inks and other surface contaminations; the surface shall be free from precipitations or smut from alloying elements or pre-processes indicated by the bright and uniform appearance of the surface; parts/areas that do not r

25、equire anodizing shall be masked accordingly; mechanically disturbed layer shall be removed either by mechanical or chemical processes; in case of chemical pre-treatment, the final step prior to anodizing shall be acidic pickling, preferably chromate-free; in case of re-anodizing all residuals from

26、the previous anodizing shall be completely removed. prEN 4704:2010 (E) 6 5.1.2 During the anodizing process: the parts shall not be subjected to any tensile, flexure, torsion or other stress; the process shall performed such, that parts do not dry between single process steps (pre-treatment, anodizi

27、ng, etc.). 5.1.3 After the anodizing procedure: parts have to be adequately rinsed with water according to 5.1.4; afterwards, the parts shall be either: dried and painted within 16 h. The parts can be kept in a dry and dust-free atmosphere for 168 h before painting. or sealed to achieve the desired

28、corrosion resistance of the anodic film; appropriate measure should be taken to prevent and to eliminate possible microbiological contaminations of the rinsing bath, e.g. UV radiation. 5.1.4 Water quality: All water used for preparation of the TSA bath and for the final rinsing step as well as for t

29、he sealing process shall be demineralized. The water shall comply with the following requirements: pH value at 25 C: 5,0 - 7,0 total residue mg/l: 20 conductivity S/cm: 20 5.2 Engineering requirements 5.2.1 Requirements to the anodic film 5.2.1.1 Visual aspects The film shall be free of powdery area

30、s, burnings, blisters and discontinuities such as scratches, ruptures or other damages. 5.2.1.2 Film thickness The thickness of the anodic film shall be in a range of 2 m to 7 m. The thickness of the film can be checked by eddy current method (EN ISO 2360), optical microscope (EN ISO 1463), scanning

31、 electronic microscope (SEM), or equivalent examinations. prEN 4704:2010 (E) 7 5.2.2 Corrosion prevention performance of unpainted parts When tested in accordance to EN ISO 9227 the anodised and sealed post-treated specimens shall show: less than 2 pits/dm2; no pit shall exceed 0,8 mm in diameter; n

32、o patchy dark grey areas (spots, streaks or marks) after an exposure time of minimum 14 days according to EN ISO 9227 for 2024 T351 unclad and 7175 T7351 unclad. There can also other materials be used if they are defined between the supplier and the customer. The area of 2 mm from the specimen edges

33、 and marks shall not be evaluated. 5.2.3 Paint adhesion on anodic film The coating system shall be agreed between the interested parties. Test the adhesion in accordance with EN ISO 2409. The damage of painted specimens shall not exceed: class 0 (according to EN ISO 2409) for specimen at initial sta

34、ge; class 1 (according to EN ISO 2409) for specimen after 14 days of water immersion at (23 2) C. 5.2.4 Corrosion prevention performance of painted parts 5.2.4.1 Filiform corrosion The maximum length of the longest filament shall not exceed 2 mm on either side of the scratches at 40 days of exposure

35、 when tested in accordance with EN 3665. Alloy in accordance with 5.2.2. 5.2.4.2 Corrosion resistance There shall not be any corrosion, blister, extending further than max. 1,25 mm on either side of the scratch at 125 days of exposure when tested in accordance with EN ISO 9227. Alloy in accordance w

36、ith 5.2.2. 5.2.5 Fatigue Requirements The fatigue specimen shall be manufactured and tested in accordance with EN 6072. All the fatigue test values shall be plotted on the Whler curves presented in Annex A (mean and minimum curves). at least 50 % of the sample shall be on or above the mean curve; 90

37、 % of the samples shall be above the minimum curve. 5.3 Quality requirements 5.3.1 General requirements All process steps, parameters and tests shall be defined in a process instruction. prEN 4704:2010 (E) 8 5.3.2 Test frequency The details and frequency for permanent and regular quality control che

38、cks shall be defined by the quality assurance of the shop considering: the ageing, contamination and the efficiency of the bath; the production rate. After specific events as re-adjustment of refilling of the bathes appropriate performance of the process shall be ensured by quality tests. 5.3.3 Visu

39、al aspect of the parts All relevant areas of the parts have to be covered by the anodic film. The anodic film shall be free of powdery areas, burnings, blisters and discontinuities such as scratches, ruptures or other damages. There shall be no water stains on surfaces to which a coating is to be ap

40、plied. The parts have to be inspected by naked eyes under constant light conditions. Checking of powdery areas or dusting is made with the help of a white and dry rag, which is slightly rubbed on the part to check. A slight dusting may be accepted so far as the paint appearance is not altered. 5.3.4

41、 Thickness of anodic film The thickness of the film can be checked by eddy current method (EN ISO 2360), optical microscope (EN ISO 1463), scanning electronic microscope (SEM), or equivalent examinations. Alternatively 5.3.7 can be applied. 5.3.5 Film weight The film weight shall be 22 mg/dm2when te

42、sted. The film weight shall be determined in accordance with EN 12373-2. Alternatively 5.3.6 can be applied. 5.3.6 Corrosion resistance of anodic film When tested in accordance with EN ISO 9227 the anodized and sealed specimens shall show: less than 2 pits/dm2; no pit shall exceed 0,8 mm in diameter

43、; no patchy dark grey areas (spots, streaks or marks) after an exposure time of minimum 14 days for 2024 T351 unclad and 7175 T7351 unclad. 5.3.7 Sealing quality After rinsing and scrubbing under water with a cotton cloth, the blue discoloration of the sealed surface shall be very light (a very fain

44、t colour is allowable) or have completely disappeared when tested in accordance with EN 2101, Annex B. prEN 4704:2010 (E) 9 5.3.8 Paint adhesion Refer to 5.2.3 however: specimen shall be painted before 16 h after anodizing; adhesion testing is performed according to EN ISO 2409 at initial stage only

45、. 5.3.9 Quality check of the processsummary All series production checks are summarized in Table 1 below. Table 1 Serial checks and minimum checking frequencies (see also 5.3.2) Property Requirement Frequency Material a No of specimens per alloy Visual aspect of parts 5.3.3 in accordance with EN ISO

46、 15528, Table 1 all parts Not applicable Thickness of anodic film 5.3.4 regular, to be agreed between the interested parties; after bath filling; after production interruption. 2024 T3 clad 7175 T7351 unclad 2 Film weight (optional) 5.3.5 regular, to be agreed between the interested parties; after b

47、ath filling; after production interruption. 2024 T3 clad 7175 T7351 unclad 2 Corrosion resistance 5.3.6 regular, to be agreed between the interested parties; after bath filling; after production interruption. 2024 T3 unclad 7175 T7351 unclad 3 Sealing quality 5.3.7 regular 2024 T3 clad or unclad rel

48、evant production alloys 1 Paint adhesion 5.3.8 regular 2024 T3 clad or unclad relevant production alloys 1 aThere can also other materials be used if they are defined between the supplier and the customer. prEN 4704:2010 (E) 10 6 Re-anodizing One re-anodizing is allowed; any further re-anodizing sha

49、ll be agreed between the interested parties. 7 Qualification test report (QTR) The qualification test report shall document the qualification tests performed and its results. It shall include at least all the following information: a) the name and address of the production shop; b) the process instruction; c) all the details regarding surface preparation (alkaline degreasing, acidic pickling etc.); d) the