1、CEN PREN*2535 94 3404589 0070756 896 Edition approved for publication AECMA STANDARD NORME AECMA AECMA NORM Comments should be sent within six months C7 Chairman after the date of publication to prEN 2535 Edition P 1 August 1994 DITE PAR LASSOCIATION EUROPEENNE DES CONSTRUCTEURS DE MATRIEL AEROSPATI
2、AL Technopolis - 175, rue Jean-Jacques Rousseau - F-92138 Issy-les-Moulineaux Cedex - Tl. (1) 47.36.98.76 UDC : Descriptors : ENGLISH VERSION Aerospace series Vacuum deposition of cadmium Srie arospatiale Cadmiage sous vide Luft- und Raumfahrt Aufdampfen von Kadmium im Vakuum This “Aerospace Series“
3、 Prestandard has been drawn up under the responsibility of AECMA (Association Europenne des Constructeurs de Matriel Arospatial). It is published on green paper for the needs of AECMA-Members. It has been technically approved by the experts of the concerned Technical Committee following comment by t
4、he 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 signature of the AECMA Standard Checking C
5、entre 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 Standardiza tion) for formal vote. 1994-08-31 Mr Bottrell AECMA Technopolis - 175, rue Jean-Jacques Rousseau 921 38 Issy-les-Moulineaux Ce
6、dex - FRANCE I I aecma 190 CEN PRENr2535 94 3404589 0070757 722 Page 3 EN 2535 : 1994 1 Scope This standard defines the method for depositing cadmium layers according to the vacuum deposition process, for use in aerospace construction. According to this process, cadmium metal is vaporised under vacu
7、um and deposited directly on the base material with an interlayer. The coating produced in this way is ductile and electrically conductive. This standard shall be applicable whenever referenced. 2 Nonnative references This European Standard incorporates by dated or undated reference, provisions from
8、 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 this European Standard only when incorporated in it by amendmen
9、t or revision. For undated references the latest edition of the publication referred to applies. IS0 1463 IS0 2082 IS0 2177 IS0 21 78 IS0 2819 IS0 4520 IS0 9227 EN 2000 EN 2409 EN 2828 3 Metallic and oxide coatings - Measurement of coating thickness - Microscopical method Metallic coatings - Electro
10、plated coatings of cadmium on iron or steel Metallic coatings - Measurement of coating thickness - Coulometric method by anodic dissolution Non-magnetic coatings on magnetic substrates - Measurement of coating thickness - Magnetic method try 1450 MPa. It may be beneficial to tensile bolts of Rm max.
11、 1250 MPa. ) In preparation at the date of publication of this standard Previous page is blank I CEN PREN*2535 94 3404589 0070758 bb = Page 4 EN 2535 : 1994 4 Limitation of process use The contact of cadmium-plated parts with titanium, titanium alloys, fuels and fuel line shall be avoided at tempera
12、ture 3,2 mm) -3% Class C : 5 - 10 pm (for bolts with a thread diameter I 3,2 mm) 7 Apparatus and materials 7.1 Vacuum enclosure The vacuum enclosure shall contain the following equipment: - a variable heating system for vaporisation of the cadmium ; - a rotating device to achieve a regular coating ;
13、 - a vaporising dish ; - a glow system and a vacuum gauge as well as an inspection window. Furthermore, a pump system is required, allowing a vacuum of at least 6,65 x IOe3 Pa to be reached. 7.2 Deposition material The cadmium used for deposition shall be at least 99,95 % pure. The mercury content s
14、hall not exceed the maximum level of 0,004 %. The quality shall be confirmed by certificate. 7.3 Masking material The masking materials used, such as masking varnishes, lead or textile tapes, paper or aluminium foils shall not release gases during the process. E Page 5 EN 2535 : 1994 a Information f
15、or the processor In addition to the designation in 18, the following information shall be stated : , - number of the substrate standard and metallurgical condition of the substrate ; - surface to be treated ; - non specific coating thicknesses of the cadmium coating and tolerances ; - if post-treatm
16、ent by chromating does not have to be carried out. 9 Condition of parts prior to processing 9.1 General Unless otherwise specified, all machining operations, moulding, brazing and welding treatments as well as heat treatments, shall be completed before plating. 9.2 Stress relief treatment The condit
17、ions for stress relief treatment of steel parts shall be determined according to the nature and hardness of the material. A slight discoloration by superficial oxidation is permitted. Shot peening according to EN 2409, if required, shall be carried out after stress relief treatment. 10 Process sched
18、ule Unless otherwise specified, the following process schedule is mandatory : degreasing ; abrasive blasting ; degreasing (if necessary, e.g. to remove any abrasive residues) ; suspension in the device ; evacuation of the enclosure ; ionic etching (sputter cleaning) (if necessary) ; deposition ; flo
19、oding and venting of the enclosure ; removal ; chromating ; preservation or application of paint. 11 Pre-treatment NOTE : Chemical or electrochemical process such as acid pickling, electrolytic cathodic degreasing or processes causing hydrogen embrittlement are not permitted for steels of Rm max. 14
20、50 MPa. 11.1 Degreasing The parts shall be cleaned by appropriate and qualified organic solvents. NOTE : After pre-treatment the parts shall be coated within 4 h. Otherwise, the parts shall be stored for a short time either under vacuum, in an inert gas atmosphere, in anydrous ethanol, or in anydrou
21、s acetone. CEN PREN*i2535 94 W 3404589 0070760 217 Page 6 EN 2535 : 1994 11.2 Abrasive blasting The parts shall be cleaned by abrasive blasting in such a way that the surface is of a uniform mat appearance. For this operation, care shall be taken to see that the compressed air is de-oiled by a speci
22、al filter. Parts cleaned by abrasive blasting shall not be rougher than specified in the design documents for the finished cadmium-plated surface. After grit blasting, all parts shall be cleared of blasting medium residues, e.g. by blowing with oil free compressed air. Where wet blasting is used, th
23、e part shall be carefully dried after treatment. 12 Treatment 12.1 Suspension and clamping of parts The parts shall be placed in such a way that a regular deposition is ensured, if necessary by means of appropriate supporting jigs. Attachment magnets may also be used for attachment, but this require
24、s demagnetisation of the parts after the cadmium-plating process. The parts may undergo the treatment several times to ensure a regular coating at the required thickness. For each batch, the required test samples shall be put in the deposition device at the same time. 12.2 Evacuation shall be carrie
25、d out until a vacuum of at least 1,33 x 1 O-2 Pa is obtained. Evacuation of the enclosure (primary vacuum) 12.3 Sputter cleaning Before starting the deposition operation, ionic etching shall be applied with a suitable inert gas (e.g. argon) to obtain a final cleaning of the parts. The part is used a
26、s a cathode. The current and etching time shall be selected according to the installation and the geometry of the part in order to ensure optimum cleaning. 12.4 Deposition Before starting the actual deposition process, the operational vacuum shall be regulated according to the specific characteristi
27、cs of the part. The deposition times for the required coating thickness shall be determined by preliminary tests. The depositions progress, especially the performance of the rotating system, shall be monitored during the process. It is permissible to re-load the vaporising dish several times with ca
28、dmium to obtain particularly thick layers. However, if the vacuum in the chamber has been disturbed, the vacuum shall be restored to its operational level before any further deposition. 12.5 Flooding, venting Afler deposition, clean dry air shall be admitted to the enclosure. The enclosure shall not
29、 be opened until the external pressure has been reached and it has been assured that no molten cadmium remains in the vaporising dish. 12.6 Removal When the enclosure has been opened and during removal, the parts shall not be touched with bare hands. The parts shall only be handled with clean gloves
30、 until their final treatment (e.g. chromating, greasing, oiling) is complete. The same standard of hygiene is required for storage surfaces or packaging. CEN PREN*2535 74 = 3404587 00707bL 153 Page 7 EN 2535 : 1994 13 Post-treatment 13.1 Chromating A post-treatment by chromating shall be carried out
31、 according to EN 2437 within 8 h following the deposition. If parts are not to be chromated, this shall be indicated in the design documents. The colour is specified according to IS0 4520 - class 2-C. 13.2 Additional protection The nature and type of any additional protection after cadmium-plating s
32、hall be specified in the design document. 14 Removal of the coating 14.1 Chemical process Defective cadmium coatings shall be chemically removed with a solution which does not attack the basic material (e.9. 100 g/l to 300 gil ammonium nitrate solution at ambient temperature for approximately 10 min
33、). The parts are then thoroughly rinsed in clean water and dried. 14.2 Mechanical process It is preferable to remove the cadmium coating by abrasive blasting, as this method avoids any embrittlement by hydrogen absorption. Care shall be taken during abrasive blasting so that the part is handled in s
34、uch a way as to ensure uniform removal. However, this method shall only be used in self-contained installations. ws 15 Required characteristics 15.1 Appearance All the surfaces coated under vacuum shall be of a regular mat appearance, however, a mother-of-pearl type surface is not a cause for reject
35、ion. The cadmium layer shall not have any blisters, pores, cracks, contamination or irregularities. It shall not have any powdery or dark areas. 15.2 Thickness of the layer It shall correspond to the indications defined in the design documents. 15.3 Adhesion The layer of cadmium shall satisfy the ad
36、hesion test according to 15.1.3. 15.4 Corrosion resistance - Cadmium-plated and chromated parts shall not show any white stains of corrosion within 96 h, nor rust within 336 h. - Non-chromated cadmium-plated parts shall not show signs of rust within 240 h. CEN PRENx2535 94 3404589 O070762 09T Page 8
37、 EN 2535 : 1994 16 Inspection 16.1 Inspection of vacuum deposited parts and samples 16.1.1 Appearance All paris shall be submitted to a visual examination. 16.1.2 Inspection of the thickness of the coating The thickness of the coating is determined using the following methods : - magnetic inductance
38、 method, see IS0 21 78 *) ; - microscopic determination, see IS0 1463 ; - by stripping and weighing, see IS0 2082 ; - coulometric method by anodic dissolution, see IS0 2177. 16.1.3 Adhesion test For this test and for each batch, at least one test panel shall be vacuum deposited at the same time. The
39、 test pieces shall be suspended at a representative place in the vacuum deposition enclosure. The test shall be camed out according to EN 2828 (burnishing test) or to IS0 281 9 (cross-wire test). 16.1.4 Corrosion test for steel Corrosion resistance shall be tested according to IS0 9227 by a salt spr
40、ay test using a solution of 5 % sodium chloride. MY For this test, pieces with a coating thickness corresponding to class B shall be prepared by vacuum deposition at the same time as the parts at a representative place in the enclosure and shall then be chromated. Material : test pieces of annealed
41、steel with a carbon content of between 0,l % and 0,18 % are to be used. Dimensions of the test pieces: (70 x 150 x 1,0-2,0) mm NOTE : All the edges of the test pieces shall be masked with suitable masking materials afier cadmium coating and before exposure to the salt spray. 17 Quality assurance 17.
42、1 Approval of the processor See EN 2000. 17.2 Process approval The processor shall carry out : - the plating on pre-production pads and/or test pieces determined by agreement between the processor and purchaser ; - the tests specified in this standard, unless otheiwise agreed between the processor a
43、nd purchaser. *) only for cadmium-plated areas which may be in contact with a 20 mm ball. CEN PREN82535 94 3404589 0070763 T2b Number of this standard I Page 9 EN 2535 : 1994 When the test results have been recognized as satisfactow by the purchaser, he shall give his written approval to start produ
44、ction. The process schedule shall not be changed without previous agreement from the purchaser. 17.3 Acceptance During production, parts and/or samples which have been coated under the same conditions as the parts shall undergo testing. Unless otherwise specified, the whole batch shall be submitted
45、to visual examination (see 14.1). Unless otherwise specified, adhesion tests (see 15.1.3) are to be carried out at a rate of one part or one sample per batch. Unless otherwise specified, the thickness of the coating shall be measured (see 15.1.2) by sampling according to IS0 2859-1 : - code letter o
46、f the sample size, table 1, special inspection level S3 ; - single sampling plan for a more thorough examination ; - acceptable quality level (AQL) 13. The frequency and nature of other subsequent tests shall be determined by agreement between the processor and the purchaser. 17.4 Reprocessing Retou
47、ching of parts not meeting the requirements is not permitted. Upon agreement from the purchaser, the paris not meeting the requirements shall be stripped of cadmium (see 13) and retreated. ia Health, safety and environmental aspects National laws and legal provisions shall be respected. 19 Designation EXAMPLE :
