1、STD-AECMA PREN 2808-ENGL 177b 1012311 0012871 515 aecma 1966 AECMA STANDARD NORME AECMA AECMA NORM prEN 2808 Edition 1 January 1996 PUBLISHED BY THE EUROPEAN ASSOCIATION OF AEROSPACE INDUSTRIES (AECMA) Gulledelle 94 - B-1200 BRUXELLES - Tel. (32) 2 775 81 10 - Fax. (32) 2 775 81 11 ICs : 49.040.40 D
2、escriptors : Aircraft industry, anodizing, titanium, titanium alloys ENGLISH VERSION Aerospace series Anodizing of titanium and titanium alloys Srie arospatiale Anodisation du titane et des alliages de titane Luft- und Raumfahrt Anodisieren von Titan und Titanlegierungen This “Aerospace series“ Stan
3、dard 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 Standardization) for
4、formal vote. Edition approved for publication 1 996-0 1 -3 1 _ The equivalent versions in French and German languages can be supplied by B.N.A.E. - Technopolis 54 - 199, rue Jean-Jacques Rousseau r 92138 ISSY - LES - MOULINEAUX CEDEX - FRANCE STD-AECMA PREN 280A-ENGL 377b W LOL23LL 0032872 453 M Pag
5、e 3 EN 2808 : 1996 I Scope This standard specifies the anodizing of titanium and titanium alloys. It shall be applicable whenever referenced. 2 Purpose of the process To improve the adhesion, especially of solid film lubricants, or to achieve a distinctive bluish violet colour. 3 Limitation of appli
6、cation of the process This process does not apply to riveted or spot welded assemblies. 4 Normative references This European Standard incorporates by dated or undated reference provisions from other publications. These normative references are cited at the appropriate places in the text and the publ
7、ications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN 2000 Aer
8、ospace series - Quality assurance - EN aerospace products - Approval of the quality system of manufacturers EN 2497 Aerospace series - Dry abrasive blasting of titanium and titanium alloys 5 Definitions For the purposes of this standard, the following definitions apply. 5.1 bath. Batch : Unless othe
9、rwise specified, it comprises parts treated at the same time in the same 5.2 Pre-production parts : Parts that are representative for future production. 6 Information for the processor - Designation, see 15 ; - number of the material standard and metallurgical condition of the latter ; areas to be p
10、rocessed, if necessary. - 7 Condition of parts prior to processing All welding, brazing, heat treatments and machining operations (with the exception of those possibly performed on the anodic coating) shall have been completed before processing the part. Previous page is blank STD.AECHA PREN 28A-ENG
11、L L77b 3n123LL 0032873 378 Page 4 EN 2808 : 1996 8 Pre-treatments 8.1 Cleaning by abrasive blasting The oxidized parts shall be cleaned by wet abrasive blasting with fine-grain alumina after agreement between the purchaser and processor or according to EN 2497. 8.2 Solvent cleaning Greasy parts may
12、be previously cleaned by suitable qualified solvents. The use of methyl alcohol is not permitted. Chlorinated solvents may cause stress corrosion cracking and shall only be used after agreement between purchaser and processor. 8.3 Alkaline cleaning 8.3.1 All parts shall be cleaned in a mild alkaline
13、 solution. Any suitable commercial products may be used. The concentration limits, temperature and immersion time shall be defined by technical data provided by the manufacturer of the product. 8.3.2 Parts shall be rinsed immediately after cleaning in running tap water. Counter-current rinsing is re
14、commended. Following rinsing, a water-break free surface is required. When a break occurs, the parts shall be reprocessed to 8.3.1. 8.4 Pickling 8.4.1 dissolution. Pickling removes small abrasive particles and provides a mild etching action by chemical 8.4.2 to conditions agreed by the purchaser. A
15、composition that has proved suitable is given in annex A. Pickling is performed in a solution of nitric and hydrofluoric acids of controlled composition 8.4.3 is recommended. Parts shall be rinsed immediately after pickling in running tap water. Counter-current rinsing 9 Treatment 9.1 example for an
16、 aqueous solution of sulphuric acid giving good results is shown in annex B. The process used shall make it possible to meet the requirements specified in 11. An The jigs or racks with spring contacts shall be made of titanium. 9.2 Parts shall be rinsed in tap water for a minimum of 2 min. Final rin
17、sing shall be by immersion of the parts in deionized water (conductivity S 20 pS/cm). Parts shall be dried, e.g. in clean compressed air, immediately after final rinsing. 9.3 avoid contamination of the anodized surface. Handling of anodized parts shall be kept to a minimum. Operators shall wear clea
18、n gloves to A dry lubricant or paint shall be applied, if appropriate, without delay after final drying. STD-AECMA PREN 2808-ENGL L77b LOL23LL 0012874 22Li Page 5 EN 2808 : 1996 10 See annex A. Removal of the anodic coating 11 Required characteristics The parts shall be of bluish violet colour match
19、ing, if required, an agreed colour sample made of the same titanium alloy and heat treated under the same conditions as the anodized parts. 12 Inspection method Visual inspection with the naked eye. 13 Quality assurance 13.1 Approval of the processor See EN 2000. 13.2 Process qualification Prior to
20、production, the processor shall treat the pre-production parts and/or test pieces determined by an agreement between the purchaser and processor. These coated pre-production parts and/or test specimens shall be submitted to the inspection described in the present standard (see 12) unless a special a
21、greement between the purchaser and processor exists. If the results are accepted as satisfactory by the purchaser, he shall give a written approval to carry out the treatment. The procedure shall not be modified without previous approval from the purchaser. 13.3 Acceptance The appearance inspection
22、(see 11 and 12) shall be carried out on the whole batch unless otherwise specified. The anodic coating shall be removed (see IO) from parts not meeting the requirements. They shall then be reprocessed (see 9). In some special cases the purchaser may agree to a local touch-up by brushing, for example
23、 with a aqueous solution of sodium carbonate (8 g/l to 12 g/l). i4 Health, safety and environmental aspects The locally applicable regulations and laws shall be observed. STD.AECMA PREN 2808-ENGL 377b 1OL23LL 0032875 LbO Page 6 EN 2808 : 1996 15 Designation EXAMPLE : Number of this standard m STD.AE
24、CMA PREN 2808-ENGL 177b = 10123LL 001287b OT7 Page 7 EN 2808 : 1996 Annex A (informative) Pickling of titanium and removal of the anodic coating - Nitric acid (HNO,) - Hydrofluoric acid (HF) - Dissolved titanium - Temperature - Immersion time - HNO,/HF ratio : : 180 g/l to 380 g/l 13 g/l to 21 g/l 1
25、 g/l : 15 Octo 30 OC 20 s to 30 s 10 The solution shall be stirred prior to the processing of parts. Stirring during processing is recommended. The nitric/hydrofluoric acid ratio shall remain within the fixed limits in order to avoid the absorption of hydrogen by the parts. The water shall contain a
26、 maximum of 150 ppm of dissolved solids. STD-AECMA PREN 2808-ENGL 177b m LOL23LL 0032877 T33 Page 8 EN 2808 : 1996 Annex 6 (informative) Anodizing - Sulphuric acid (HSO,) - Chloride (as NaCl) - Time - Voltage - Current density (initial) 50 g/l to 400 g/l 200 ppm : necessary to obtain the desired colour 15Vto20V 0,2 A/dm2 to 0,4 A/dm2 The sulphuric acid concentration shall have a precision of i 10 %, with respect to the specified value. The electrolyte may contain additional components authorized by the purchaser. The water conductivity shall be I 10 pS/cm.
