1、AECMA STANDARD NORME AECMA AECMA NORM prEN 3765 Edition P 1 April 1997 PUBLISHED BY THE EUROPEAN ASSOCIATION OF AEROSPACE INDUSTRIES (AECMA) Gulledelle 94 - 8-1200 BRUXELLES - Tel. (32) 2 775 81 10 - Fax. (32) 2 775 81 11 ICs : Descriptors : ENGLISH VERSION Aerospace series Electrolytic silver plati
2、ng for general use Steels, heat resisting alloys, copper and copper alloys Srie arospatiale Luft- und Raumfahrt Argentage lectrolytique pour usage gnral Aciers, alliages rsistant chaud, cuivre et alliages de cuivre Elektrolytisches Versilbern fr allgemeinen Gebrauch hochwarmfeste Sthle, Legierungen
3、Kupfer und Kupferlegierungen This “Aerospace Series“ Prestandard has been drawn up under the responsibility of AECMA (The European Association of Aerospace Industries). It is published on green paper for the needs of AECMA-Members. It has been technically approved by the experts of the concerned Tec
4、hnical Committee following comment by the Member countries. 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 the standard. After examination and sig
5、nature of the AECMA Standard Checking Centre (NPS) and formal agreement of the Official Services of the Member countries it will be submitted as a draft European Standard to CEN (European Committee for Standardization) for formal vote. Nota - Extra copies can be supplied by B.N.A.E. - Technopolis 54
6、 - 199, rue Jean-Jacques Rousseau - 921 38 ISSY-LES-MOULINEAUX CEDEX Edition approved for publication 1997-04-30 Comments should be sent within six months after the date of publication to AECMA Gulledeiie 94 B-1200 BRUXELLES C7 Chairman Mr Wright aecma 199; STD*AECMA PREN 37b5-ENGL 1777 W L03231L 00
7、32773 277 Page 3 prEN 3765 : 1997 1 Scope This standard defines the electrolytic silver plating of steels, heat resisting alloys, copper and copper alloys used in aerospace construction. 2 Normative references This European Standard incorporates by dated or undated reference provisions from other pu
8、blications. 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 this European Standard only when incorporated in it by amendment or revi
9、sion. For undated references the latest edition of the publication referred to applies. IS0 1463 IS0 2177 IS0 2859-1 IS0 3882 EN 2000 EN 2828 EN 2829 EN 2830 EN 2831 EN 2832 Metallic and oxide coatings - Measurement of coating thickness - Microscopical method Metallic coatings - Measurement of coati
10、ng thickness - Coulometric method by anodic dissolution Sampling procedures for inspection by attributes - Part 1 : Sampling plans indexed by acceptable quality level (AQL) for lot-by-lot inspection Metallic and other non-organic coatings - Review of methods of measurements of thickness Aerospace se
11、ries - Quality assurance - EN aerospace products - Approval of the quality system of manufacturers Aerospace series - Adhesion test for metallic coatings by burnishing Aerospace series - Adhesion test for metallic coatings by shot peening Aerospace series - Adhesion test for metallic coatings by she
12、aring action Aerospace series - Hydrogen embrittlement of steels - Test by slow bending Aerospace series - Hydrogen embrittlement of steels - Notched specimen test 3 Purpose of process To prevent fretting or seizure. 4 Definitions For the purposes of this standard, the following definitions apply Ba
13、tch : Unless otherwise specified, it comprises parts of the same nature (shape, size, material) treated at the same time in the same bath and after having undergone the same pre-treatment and post-treatment. Ra : Surface condition - Arithmetic mean deviation of roughness, expressed in pm. Rm(max.) :
14、 Maximum specified tensile strength. STD-AECMA PREN 37b5-ENGL 11997 E LDL23bL 00112974 LU5 E Page 4 prEN 3765 : 1997 5 Classification of coatings 5.1 Type A Electrodeposit of silver, on a nickel strike with or without an undercoat of nickel, applied to parts which may reach 760 OC in continuous oper
15、ation. 5.2 Type B Electrodeposit of silver, on a copper undercoat, applied to parts which may reach a maximum of 150 OC in continuous operation. 6 Information for the processor In addition to the designation (see 151, the following information shall be given : the reference of the substrate standard
16、 and the metallurgical condition of the substrate ; the areas to be treated ; the duration and temperature of heat treatments before and after processing ; the electrical contact points or the areas where these are prohibited ; the surface of the part in dm2 ; if required, the mechanical finishing.
17、Condition of parts prior to processing Manufacturing process All welding, brazing, heat treatments including stress relief and machining operations, with the exception of those possibly performed on the coating, shall have been completed before coating. The stress relief heat treatment conditions sh
18、all be determined according to the nature and the strength of the material. Stress relief treatment of nickel and copper alloys is not required. A slight discoloration by superficial oxidation is permitted. 7.2 Surface roughness Unless otherwise specified the functional areas of the part to be coate
19、d shall have : Ra 1450 MPa Steels with R, (max.) I 1450 MPa Case hardened steels and other materials Type A 1) . Minimum Time 18 h 2h 5h Substrate I Type - Steels with 1 1 O0 I R, (max.) I 1450 MPa Steels with R, (max.) 1450 MPa B I Other materials see annex C 3 see annex D 4 3 A Heat resisting stee
20、ls and heat resisting alloys 2 4 3 2 3 2 3 3 Copper and I I 1 copper alloys 1 2 _ _ _ 1) Applies exclusively to parts not exposed to corrosion (e.g. parts inside sealed casing) 9 Post-treatment It shall be carried out within 24 h of coating, unless otherwise stated in the design document, in accorda
21、nce with table 2 : 130 - 150 5hto12h 130 - 150 24 h 130 - 150 Ih 1) Parts may be heat treated for a shorter time at a higher temperature if the conditions have been shown to be effective in reducing hydrogen embrittlement and do not affect the performance of the part. 10 Removal of the silver platin
22、g The solution shall not attack the base metal (example for steel : an aqueous solution of nitrobenzene sulphonate sodium salt 55 g/l to 65 g/l and sodium cyanide 90 g/l to 100 g/l, temperature 30 OC to 70 OC). 11 Required characteristics 1 1.1 Appearance The coating shall have a smooth, adherent, s
23、atin and uniform appearance, free from : - cracks ; - rough, burnt or excessive build-up ; - uncoated areas ; - pitting ; - blisters, pores or exfoliation. Some slight variation in brilliance, due to the geometry of the part is accepted. 11.2 Adhesion The deposit shall adhere to the whole surface. T
24、he deposit shall satisfy the test in 12.1 .I and 12.2.3. 11.3 Thickness Unless otherwise specified in the design document, the thickness of the silver, including any strike treatments, shall be (8 f 2) ym and the thickness of any undercoat shall be 3 ym to 10 pm. 1 1.4 Composition of the deposit Unl
25、ess otherwise specified, the deposited metal shall contain at least 99,9 % of silver for type A and 99,5 % for type B. 11.5 Hydrogen embrittlement The application of coating system shall not cause any irreversible hydrogen embrittlement. 12 Inspection 12.1 Inspection of plated parts 12.1 .I Appearan
26、ce and adhesion The visual inspection shall be made with a magnification of x 2,5 to show a lack of adhesion in the form of blisters or exfoliation. 12.1.2 Thickness 12.1.2.1 Local thickness IS0 3882. In case of dispute, IS0 21 77 or IS0 1463. 12.1.2.2 Average thickness - calculate the surface of th
27、e part ; - after degreasing, weigh the part to the nearest O, 1 mg ; - remove the coating (see clause 10) : - rinse, dry and weigh. Loss of mass (9) x 10 O00 Surface (cm21 x 10,5 (g / cm3) Average thickness in prn = Page 7 prEN 3765 : 1997 Number of encrustations On 1 mm I10 On 10 mm I50 12.2 Test p
28、ieces Total length 5 0,06 mm I0,3 mm 12.2.1 General - Test pieces shall be made from the same material, with the same heat treatment condition as the parts they represent. - They shall undergo the same treatments at the same time in the same baths as the batch they represent. - Their form shall be r
29、epresentative of areas to be treated. - Inexpensive parts may be used as test pieces. - The definition of the test pieces shall be stated in the documents specified in 13.1. 12.2.2 Metallographic examination On a section taken through the coating, no dirt or contamination shall be visible at x 300 m
30、agnification on the metakoating interface. Some inclusions within the coating are tolerated, see table 3. 12.2.3 Adhesion A test piece shall be heated at (510 f IO) OC for type A or (140 f IO) OC for type B and held for 1 h at this temperature before cooling. Examination at a magnification of x 10 s
31、hall show no blisters or exfoliation. Additionally, after heating, one of the following adhesion tests shall be carried out : EN 2828 or EN 2829 or EN 2830. 12.3 Process - calibration of measuring instruments ; - bath analyses. The following tests shall be carried out : 12.3.1 Hydrogen embrittlement
32、 - no rupture before 200 h (as EN 2832) - apart from measuring errors, initial ductility is restored as per EN 2831. Other methods may be used subject to agreement by the purchaser. 12.3.2 Analysis of the deposit The method of analysis shall be agreed upon between the manufacturer and purchaser. STD
33、-AECMA PREN 37b5-ENGL 1777 LO323L3 0032978 850 = Page 8 prEN 3765 : 1997 13 Quality assurance 13.1 Approval of the processor See EN 2000. 13.2 Process qualification Before beginning production the processor shall submit a series of pre-production parts and test pieces, made up by the first batch coa
34、ted under series conditions, on which the tests in 12 shall be performed. 13.3 Acceptance The frequency and nature of the inspection of parts and test pieces, at acceptance stage shall be subject to agreement between the manufacturer and purchaser. It shall be stated in the document required in 13.1
35、. The tests involved at acceptance shall be : - the visual inspection (1 2.1 .I - the local thickness (12.1.2.11, it shall be measured on one sample per batch defined in accordance with IS0 2859-1 : it shall be carried out on the whole batch ; - code letter of the batch size, table 1, inspection lev
36、el for special applications S3 ; - simple sampling plan under tightened inspection ; - acceptable quality level (AQL) 1,5 ; - the measuring of the adhesion on test pieces, it shall be carried out at a rate of one test piece per batch. 13.4 Fault sanction No reworking shall be permitted. All defectiv
37、e deposites shall be removed and parts shall be retreated. 14 The locally applicable regulations and laws shall be observed. Health, safety and environmental aspects 15 Designation EXAMPLE : i Number of this standard Plating type code (see 5) Nominal thickness of the undercoat in pm (O0 if no underc
38、oat is provided) Nominal thickness of the silver deposit in pm , B - STD-AECMA PREN 37b5-ENGL 1777 m 1012311 0012777 777 m Page 9 prEN 3765 : 1997 Annex A (normative) Nickel strike A.l Preparation After cleaning, masking if necessary, degreasing and pickling by a method appropriate to the material,
39、the parts receive, for example, the following treatment : A.2 Bath - nickel chloride (“212, 6H2O) - hydrochloric acid (d = 1,161 - water - current density - time : 200 g/l to 240 g/l : 80 ml/l to 110 ml/l : supplementary for 1 I : 4 A/dm2 to 8 A/dm2 : up to 3 min STD-AECMA PREN 37bS-ENGL 1777 101231
40、1 0032780 YO7 Page 10 prEN 3765 : 1997 Annex B (normative) Nickel plate B. 1 Preparation At the end of the nickel strike treatment, without intermediate rinsing, the parts are treated, for example, in one of the following baths : 8.2 “WATTS type“ nickel bath - nickel sulphate (NiS04, 7 H20) - nickel
41、 chloride (NiC12, 6 H20) - boric acid (H3B03) - temperature - current density - theoretical rate of deposition : 220 g/l to 280 g/l : 40 g/l to 50 g/l : 25 g/l to 35 g/l : 50 Octo 55 OC : : 2 A/dmz to 5 A/dm2 12 pm/h for 1 A/dm2 B.3 Nickel “Sulpharnate“ bath - nickel suiphamate expressed as Ni metal
42、 : 75 g/l to 90 g/l - nickel chloride (NiC12, 6 H20) : 25 g/l - boric acid (H3BO3) : 30 g/l to 40 g/l - temperature : 50 Octo55 OC - current density : 2 A/dmz to 8 A/dm2 - theoretical rate of deposition : 12 pm/h for 1 A/dm2 STD-AECMA PREN 37b5-ENGL 1777 LOL23LL OOL278L 345 = Page 11 prEN 3765 : 199
43、7 Annex C (normative) Silver strike c. 1 Preparation After applying an undercoat in an acid bath or a pre-treatment in an acid bath, the parts shall be neutralized in an alkaline solution. This neutralisation is not necessary in the case of an undercoat deposited in an alkaline media or having under
44、gone an alkaline pre-treatment. c.2 Silver strike bath As a typical example the following bath may be used : - silver cyanide (AgCN) : 2 g/l to 4 g/l - potassium cyanide (KCN) : 60 g/l to 80 g/l - potassium carbonate (K2CO3) : 10 g/l to 50 g/l - temperature : 15 OC to 30 OC - current density : 1 A/d
45、m2 to 2 A/dm2 - time : 15 s to 30 s with immersion of parts with current flowing STD-AECMA PREN 37b5-ENGL 1997 = LUL23LL 0032982 281 Page 12 prEN 3765 : 1997 Annex D (normative) Silver plate D. 1 Preparation After the silver strike, without intermediate rinsing, the parts can, for example, be treate
46、d in the following bath : D.2 - Silver bath silver cyanide (AgCN) potassium cyanide (KCN) potassium carbonate (K2CO3) potassium hydroxide (KOH) water temperature current density rate of deposition 37 g/l to 75 g/l 42 g/l to 96 g/l 10 g/l to 110 g/l 5 g/l to 10 g/l supplementary for 1 I 20 oc to 40 o
47、c 0,2 A/dm2 to 3 A/dm2 38 pm/h for 1 A/dm2 STD-AECMA PREN 37b5-ENGL 3777 m 3032333 0032783 338 m Page 13 prEN 3765 : 1997 Annex E (normative) Copper plate E. 1 Preparation After cleaning, masking if necessary, degreasing and pickling by an appropriate method the parts receive, for example, one of th
48、e following treatments : E.2 Acid bath (parts without masking) - copper sulphate (CuSO4, 5ii20) : 200 g/l to 250 g/l - sulphuric acid (d = 1,841 : 20 mi/ to 35 ml/l - water : Supplementary for 1 I - temperature : 18 OC to 30 OC - current density : 0,5 A/dm2 to 3 A/dm2 - theoretical rate of depositio
49、n : approx. 13 pm/h for 1 A/dm2 E.3 Alkaline bath (parts with or without masking) - copper cyanide (CuCN) : 25 g/l to 40 g/l - sodium cyanide (NaCN) : 40 g/l to 50 g/l - sodium carbonate (Na2C03) : 15 g/l to 60 g/l - sodium and potassium tartrate (Seignette or Rochelle salt) NaK (C4H406) 4 H20 : 35 g/l to 65 g/l - water : supplementary for 1 I - temperature : (40 k 5) OC - current density : 0,5 Aldm2 to 2 A/dm2 - theoretical rate of deposition : approx. 26 pm/h for 1 A/dm2
