ASD-STAN PREN 4827-2015 Aerospace series Hexavalent chromium free anodizing of aluminium and aluminium alloys (Edition P 1).pdf

1、ASD-STAN STANDARD NORME ASD-STAN ASD-STAN NORM prEN 4827 Edition P 1 January 2015 PUBLISHED BY THE AEROSPACE AND DEFENCE INDUSTRIES ASSOCIATION OF EUROPE - STANDARDIZATION Rue Montoyer 10 - 1000 Brussels - Tel. 32 2 775 8126 - Fax. 32 2 775 8131 - www.asd-stan.org ICS: Descriptors: Aluminium, alumin

2、ium alloys, cleaning, anodizing, sealing, etching, pickling, painting ENGLISH VERSION Aerospace series Hexavalent chromium free anodizing of aluminium and aluminium alloys Srie arospatiale Anodisation sans chrome hexavalent de laluminium et des alliages daluminium Luft- und Raumfahrt Hexavalentes ch

3、romfreies Anodisieren von Aluminium und Aluminiumlegierungen This “Aerospace Series“ Prestandard has been drawn up under the responsibility of ASD-STAN (The AeroSpace and Defence Industries Association of Europe - Standardization). It is published for the needs of the European Aerospace Industry. It

4、 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 interchangeability is affected, physically or functionally, without re-identification of th

5、e 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 transformation to full European Standard (EN). The CEN national members have then to implem

6、ent 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 1st January 2015 Comments should be sent within six months after the date of publication to ASD-STAN Metallic Material D

7、omain Copyright 2015 by ASD-STAN prEN 4827:2015 (E) 2 Contents Page Foreword 2 1 Scope 3 2 Normative references 3 3 Purpose of process . 4 4 Terms and definitions . 5 5 Protection system classification 6 6 Process requirements . 7 7 Engineering requirements 9 8 Quality requirements .11 Annex A (norm

8、ative) Engineering requirements 13 Annex B (normative) Quality requirements 14 Bibliography 17 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 ASD-

9、STANs General Process Manual, this standard has received approval for Publication. prEN 4827:2015 (E) 3 1 Scope This standard defines the requirements for hexavalent chromium free anodizing of aluminium and aluminium alloys for corrosion protection, bonding and painting. Hard anodizing is not covere

10、d by this standard. The purpose of this standard is to give design, quality and manufacturing requirements. It doesnt give complete in-house process instructions; these shall be given in the manufacturers detailed process instructions. 2 Normative references The following documents, in whole or in p

11、art, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 2284, Aerospace series Sulphuric acid anodizi

12、ng of aluminium and wrought aluminium alloys EN 3665, Aerospace series Test methods for paints and varnishes Filiform corrosion resistance test on aluminium alloys EN 4704, Aerospace series Tartaric-Sulphuric-Acid anodizing of aluminium and aluminium wrought alloys for corrosion protection and paint

13、 pre-treatment (TSA) EN 4707, Aerospace series Acid pickling of aluminium and aluminium alloy without hexavalent chromium 1) EN 6072, Aerospace series Metallic materials Test methods Constant amplitude fatigue testing EN ISO 1463, Metallic and oxide coatings Measurement of coating thickness Microsco

14、pical method (ISO 1463:2003) EN ISO 2085, Anodizing of aluminium and its alloys Check for continuity of thin anodic oxidation coatings Copper sulfate test (ISO 2085:2010) EN ISO 2360, Non-conductive coatings on non-magnetic electrically conductive basis materials Measurement of coating thickness Amp

15、litude-sensitive eddy-current method (ISO 2360:2003) EN ISO 2409, Paints and varnishes Cross-cut test (ISO 2409:2013) EN ISO 9220, Metallic coatings Measurement of coating thickness Scanning electron microscope method (ISO 9220:1988) EN ISO 9227, Corrosion tests in artificial atmospheres Salt spray

16、tests (ISO 9227:2012) EN ISO 2376, Anodizing of aluminium and its alloys Determination of electric breakdown potential (ISO 2376:2010) 1) Published as ASD-STAN Prestandard at the date of publication of this standard. http:/www.asd-stan.org/ prEN 4827:2015 (E) 4 3 Purpose of process The anodizing is

17、an electrochemical process voltage controlled allowing to transform the metal surface in an microporous oxide layer made of alumina. The aim of this treatment is to ensure a protection against the corrosion, and/or to be used as an adhesion base before bonding or before painting. This anodizing is g

18、enerally sealed for protection corrosion application (with or without painting or bonding) and can stay unsealed when the part is bonded or painted. This specification is applicable on aluminium and aluminium alloys generally on single parts. Hard anodizing and plasma electrolytic anodizing dedicate

19、d to wear protection are not covered by this specification. 3.1 Applicability 3.1.1 Type A: unsealed anodizing It shall be used either as surface preparation before the application of painting/ bonding or any other finishing. 3.1.2 Type B: sealed anodizing It is intended for corrosion protection. It

20、 shall be with or without dyeing and used with or without additional painting. See Table 1. Table 1 Different application cases Unsealed (type A) Sealed (type B) Unpainted Painted Bonding (structural) Unpainted Painted Sulfuric acid anodizing (SAA) EN 2284 Not applicable Applicable Not applicable Ap

21、plicable Applicable Thin film sulfuric acid anodizing (TFSAA) Tartaric sulfuric acid anodizing (TSA) EN 4704 Not defined yet with chromate free sealing Boric sulfuric acid anodizing (BSAA) Not applicable Phosphoric acid anodizing (PAA) Applicable Not applicable Sulfuric phosphoric acid anodizing (PS

22、A) prEN 4827:2015 (E) 5 3.2 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. Anodizing shall not be applied: in electric conductivity zones/areas; for tubes, pipes and open ho

23、les with a length to diameter ratio higher than 10:1 (unless using specific cathode); 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 permanently entrap treatment solutions; for components which can permanently e

24、ntrap 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. 4 Terms and definitions For the purposes of this document, the following terms and definitions apply.

25、 4.1 de-anodizing process, which removes the anodic oxide 4.2 smut precipitations of alloying elements (e. g. Cu, Fe, Zn, Si) on the surface of parts after a process step normally after alkaline etching step 4.3 Mechanically Disturbed Layer MDL Layer that is present at the surface resulting from the

26、 rolling process of the material 4.4 pit surface corrosion defect at which the anodic coating is penetrated. Typical characteristics of corrosion pits are: rounded or irregular or elongated geometry, comet tail or line or halo that emerges from the cavity, some corrosion by-products inside pits (on

27、aluminium test samples the by-product may be granular, powdery or amorphous and white, grey or black in colour). To be considered as a corrosion pit, a surface cavity must exhibit at least two of the above characteristics. 4.5 process instruction document that describes the application scopes, detai

28、led process (key parameters, detailed steps, etc.), quality management, environmental and safety regulations, etc. prEN 4827:2015 (E) 6 4.6 alloys all aluminium alloys, that are treated with the chromate free anodizing process in the specific shop 4.7 re-anodizing repetition of the anodizing process

29、 step after complete de-anodizing 4.8 sealing chromate free sealing (of the anodized layers) is applied to close the pores produced by the acid anodizing process. It is usually applied in hot demineralized water bath with or without additives at different temperatures. Sealing improves the corrosion

30、 resistance performance of the anodic film. 4.9. batch unless otherwise specified, it comprises parts of the same type (i.e. shape, size, material), processed at the same time in the same bath 5 Protection system classification 5.1 System types Anodizing layer is classified by the two following type

31、s: Type A: unsealed anodizing: It shall be used as surface preparation before the application of painting/ bonding or any other finish. Type B: sealed anodizing: It is intended for corrosion protection. It shall be with or without dyeing and used with or without additional painting. 5.2 Layer thickn

32、esses See Table 2. Table 2 Layer thicknesses corresponding to the class type Class type Typical thickness Anodizing process Class 1 1 m Phosphoric acid anodizing (PAA) Sulfuric phosphoric acid anodizing (PSA) a Class 2 2 m to 8 m Tartaric sulfuric acid anodizing (TSA) Boric sulfuric acid anodizing (

33、BSAA) Thin film sulfuric acid anodizing (TFSAA) Class 3 8 m to 25 m Sulfuric acid anodizing (SAA) a 5 m for some Aluminium alloy under agreement between purchaser and supplier. prEN 4827:2015 (E) 7 6 Process requirements 6.1 Information for the processor type and class designation, substrate standar

34、d reference and heat treatment, areas to be anodized, anodized thickness measuring points, electrical contact points or areas where these are inadmissible, specification for testing on parts and/or samples. 6.2 Condition of parts prior to the treatment Welding, soldering/brazing, mechanical operatio

35、ns and heat treatments shall have been completed. 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; mechan

36、ically disturbed layer shall be removed either by mechanical or chemical processes; in case of re-anodizing all residuals from the previous anodizing shall be completely removed. 6.3 Process conditions 6.3.1 Tooling The tools, bars, electrical contact systems, and metal masking tooling must be free

37、of corrosion or any other damage which may be detrimental to the treatment during use. The part racks and tools must be designed and set up in such a manner as to: avoid any retention of air or treatment solution in the parts, facilitate neutralization and removal of solutions during rinsing operati

38、ons, the electrical contacts must be kept in good condition for the correct passage of the current avoid any accidental contact between the parts to be treated and the tank equipment or electrodes, and between the different parts during all the process. electrical contact points should be defined be

39、tween purchaser and processor; the fixturing tools (e.g. in aluminium alloy or titanium) must provide effective electrical contact with the parts; the contact is preferably achieved at several points in order to ensure better current distribution. prEN 4827:2015 (E) 8 6.3.2 Masking The parts shall b

40、e at least degreased prior to masking. Component areas which must not be coated shall be masked with suitable material. 6.3.3 Surface pre-treatment Surface preparation means any method able to completely eliminate all surface contaminations. In case of chemical pre-treatment, the final step prior to

41、 anodizing shall be acidic pickling, preferably chromate-free; Anodizing must be performed immediately after pickling (in accordance with aluminium and aluminium alloys pickling standard EN 4707). 6.3.4 Anodizing During the anodizing process: distance between part and electrode must be defined to ha

42、ve the requested anodic layer thickness without electrical arc; parts should be fully immersed; 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, anodizing, etc.); th

43、e anodizing parameters (temperature, voltage, time) shall be adapted to the material and its requirements in accordance with the bath composition. in case of re-anodizing, the former protection will have to be totally removed before (chemically or mechanically) (see 6.5). 6.3.5 Anodizing post treatm

44、ents After the anodizing procedure: parts have to be adequately rinsed with water according to 6.4; afterwards, the parts shall be either: dried immediately afterwards and painted within 16h; this time can be extended in accordance with customer requirements. In this case, it is recommended to handl

45、e the parts output anodizing treatment with gloves. dried immediately afterwards and bonded within 8h this time can be extended in accordance with customer requirements. In this case, it is recommended to handle the parts output anodizing treatment with gloves. sealed with chromate free solution to

46、achieve the desired corrosion resistance of the anodic film. prEN 4827:2015 (E) 9 6.4 Water quality All water used for bath make-up and addition of the anodizing and for the final rinsing step as well as for the sealing process shall be demineralized. 6.4.1 Anodizing bath The water shall comply with

47、 the following requirements: pH value at 25 C: 5,0 to 8,0 total residue mg/l: 5 conductivity S/cm: 2 6.4.2 Sealing and dyeing bathes The water shall comply with the following requirements: pH value at 25 C: 5,0 to 8,0 total residue mg/l: 5 conductivity S/cm: 2 Silica content mg/l: 1 6.4.3 Rinsing ba

48、th The water shall comply with the following requirements: pH value at 25 C: 5,0 to 8,0 total residue mg/l: 5 conductivity S/cm: 20 6.5 Re-anodizing One re-anodizing is allowed; any further re-anodizing shall be agreed between the interested parties. 7 Engineering requirements The anodizing is expec

49、ted to meet the main requirements summed-up in Table A.1 in Annex A. 7.1 Visual aspects The film shall be free of powdery areas, burnings, blisters and discontinuities such as scratches, ruptures or other damages. 7.2 Film thickness The thickness of the film can be checked by eddy current method (EN ISO 2360) which may b