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1、SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefr
2、om, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2007 SAE International All rights reserved. No part of this publication may
3、 be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER:Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA) Fa
4、x: 724-776-0790 Email: custsvcsae.org SAE WEB ADDRESS:http:/www.sae.org Coating, Cadmium Vacuum Deposition RATIONALE This document has been reaffirmed to comply with the SAE 5-year Review policy. 1.SCOPE: 1.1Purpose: This specification covers the engineering requirements for vacuum deposition of cad
5、mium and the properties of the deposit. 1.2Application: This process has been used typically to provide a corrosion resistant coating for high strength ferrous parts operating at not higher than 450 F (232 C) and requiring freedom from hydrogen embrittlement, but usage is not limited to such applica
6、tions. Deposits are “line-of-sight” and may not be applicable to some internal surfaces. 1.3Safety - Hazardous Materials: While the materials, methods, applications, and processes described or referenced in this specification may involve the use of hazardous materials, this specification does not ad
7、dress the hazards which may be involved in such use. It is the sole responsibility of the user to ensure familiarity with the safe and proper use of any hazardous materials and to take necessary precautionary measures to ensure the health and safety of all personnel involved. AEROSPACE MATERIAL SPEC
8、IFICATION AMS 2426D IssuedSEP 1966 RevisedSEP 2002 ReaffirmedAPR 2007 Superseding AMS 2426C Copyright SAE International Provided by IHS under license with SAELicensee=Defense Supply Ctr/5913977001 Not for Resale, 12/04/2007 20:25:15 MSTNo reproduction or networking permitted without license from IHS
9、 -,-,- AMS 2426DSAEAMS 2426D - 2 - 1.4Warning: This document includes cadmium as a coating material. The use of cadmium has been restricted and/or banned for use in many countries due to environmental and health concerns. The user should consult with local officials on applicable health and environm
10、ental regulations regarding its use. 2.APPLICABLE DOCUMENTS: The issues of the following documents in effect on the date of the purchase order forms a part of this specification to the extent specified herein. The supplier may work to a subsequent revision of a document unless a specific document is
11、sue is specified. When the referenced document has been canceled and no superseding document has been specified, the last published issue of that document shall apply. 2.1ASTM Publications: Available from ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959 or www.astm.org. ASTM B 117Operat
12、ing Salt Spray (Fog) Testing Apparatus ASTM B 487Measurement of Metal and Oxide Coating Thicknesses by Microscopical Examination of a Cross Section ASTM B 499Measurement of Coating Thicknesses by the Magnetic Method; Nonmagnetic Coatings on Magnetic Basis Metals ASTM B 504Measurement of Thickness of
13、 Metallic Coatings by the Coulometric Method ASTM B 568Measurement of Coating Thickness by X-Ray Spectrometry ASTM B 571Adhesion of Metallic Coatings 3.TECHNICAL REQUIREMENTS: 3.1Preparation: 3.1.1Ferrous parts heat treated to a range including or exceeding a tensile strength of 240 ksi (1655 MPa) o
14、r hardness of 49 HRC shall not be exposed to processes which cause hydrogen embrittlement, such as pickling, cathodic cleaning, and etching, or to corrosive environments. 3.1.2Ferrous parts heat treated to a range including or exceeding a tensile strength of 180 ksi (1241 MPa) or hardness of 40 HRC,
15、 excluding the tensile strength of 240 ksi (1655 MPa) or 49 HRC or greater, which have been exposed to processes which cause hydrogen embrittlement shall be heated to 375 F 25 (191 C 14) and held at heat for not less than three hours prior to coating, except carburized parts which shall be held at 2
16、75 25 F (135 14 C) for not less than five hours prior to coating. 3.1.3Parts shall be within specified dimensional tolerances after coating. Copyright SAE International Provided by IHS under license with SAELicensee=Defense Supply Ctr/5913977001 Not for Resale, 12/04/2007 20:25:15 MSTNo reproduction
17、 or networking permitted without license from IHS -,-,- AMS 2426DSAEAMS 2426D - 3 - 3.2Procedure: 3.2.1Cadmium shall be deposited directly onto the basis metal without a preliminary coating of other metal. 3.2.2Parts shall be coated by deposition of vaporized metallic cadmium within a suitable vacuu
18、m. 3.2.2.1The equipment and processes employed shall be adequate to ensure coverage of all external surfaces, including roots of threads, recesses, and sharp corners. 3.2.3After coating, parts shall be conversion coated. Unless otherwise specified, a chromate conversion coating shall be used. 3.3Pro
19、perties: The cadmium coating shall conform to the following requirements: 3.3.1Thickness: Shall be as specified on the drawing, determined on representative parts in accordance with ASTM B 487, ASTM B 499, ASTM B 504, ASTM B 568, direct micrometer measurement, or other method acceptable to purchaser
20、. 3.3.1.1Coating thickness, when specified by AMS 2426 and a suffix number, shall be as specified in Table 1 for the specified suffix number and type of part or surface. TABLE 1 - Coating Thickness and Salt Spray Corrosion Resistance Requirements AMS 2426 Thickness Designation Specified External Thr
21、eads Thickness Inch External Threads Thickness Micrometers External Threads Salt Spray Resistance Hours, min Nuts, Washers, and Unthreaded Surfaces of Parts Externally Threaded Thickness Inch Nuts, Washers, and Unthreaded Surfaces of Parts Externally Threaded Thickness Micrometers Nuts, Washers, and
22、 Unthreaded Surfaces of Parts Externally Threaded Salt Spray Resistance Hours, min Parts Not Externally Threaded except Nuts and Washers Thickness Inch Parts Not Externally Threaded except Nuts and Washers Thickness Micrometers Parts Not Externally Threaded except Nuts and Washers Salt Spray Resista
23、nce Hours, min 24260.0001 2.51000.0002 5.11500.0003 7.6200 0.0004100.000512.70.000513 2426-10.0001 2.51000.0002 5.11500.0001 2.5100 0.0003 7.60.0004100.0003 7.6 2426-20.0001 2.51000.0002 5.11500.0002 5.1150 0.0004100.0004100.000410 2426-30.0002 5.11500.0003 7.62000.0003 7.6200 0.0005130.0005130.0005
24、13 2426-40.0003 7.62000.0004102250.000410225 0.0006150.0006150.000615 2426-50.0004102250.0005132500.000513250 0.0007180.0007180.000718 Notes: For thickness designations AMS 2426-X, where X is greater than 5, coating thickness in ten-thousandths of an inch shall be X to X+2 except on external threads
25、 where coating thickness shall be X-1 to X+2; such parts shall withstand salt spray for not less than 250 hours. For thickness designations AMS 2426-X, where X is greater than 5, coating thickness in micrometers shall be 2.5X to 2.5 (X+2) except on external threads where coating thickness shall be 2
26、.5 (X-1) to 2.5 (X+2); such parts shall withstand salt spray for not less than 250 hours. Copyright SAE International Provided by IHS under license with SAELicensee=Defense Supply Ctr/5913977001 Not for Resale, 12/04/2007 20:25:15 MSTNo reproduction or networking permitted without license from IHS -
27、,-,- AMS 2426DSAEAMS 2426D - 4 - 3.3.1.2Where “cadmium flash” is specified, coating thickness shall be approximately 0.0001 inch (2.5 m). 3.3.1.3The coating shall be substantially uniform in thickness on significant surfaces except that slight build-up on exterior corners or edges will be permitted
28、provided finished drawing dimensions are met. 3.3.1.4Requirements are not established for minimum coating thickness for surfaces of holes, recesses, internal threads, contact areas of parts coated all over, and other areas where a controlled deposit cannot be obtained under normal coating conditions
29、, but such areas shall not normally be masked to prevent coating. Except as specified in Table 1 for externally threaded sections, the resultant thickness shall be considered only when such surfaces of parts can be touched by a sphere 0.75 inch (19.0 mm) in diameter. 3.3.2Adhesion: Shall be determin
30、ed using one of the following methods: 3.3.2.1Coating shall not show separation from the basis metal when tested in accordance with a method described in ASTM B 571. 3.3.2.2Coating shall not show separation from the basis metal when tested using a pressure sensitive tape with 2.5 pounds per inch (44
31、6 grams per centimeter) minimum peel strength. The tape shall be applied to the coated surface, rolled into place using a rubber roller, and then rapidly removed by peeling the tape at a 90-degree angle to the coated surface. 3.3.3Corrosion Resistance: Except as specified in 3.3.3.1, ferrous metal p
32、arts or representative test panels processed with parts represented shall show no visual evidence of corrosion of the basis metal after being subjected for a time not less than specified in Table 1 to continuous salt spray corrosion test conducted in accordance with ASTM B 117. When test specimens a
33、re used, coating thickness shall be 0.0002 to 0.0004 inch (5 to 10 m). Corrosion resistance shall not apply to parts coated to a thickness less than 0.0002 inch (5 m) or to surfaces of parts such as holes, recesses, or internal threads which may have less than 0.0002 inch (5 m). 3.3.3.1Salt spray co
34、rrosion tests shall not apply to nonferrous parts, coated parts made of austenitic corrosion resistant steels, to areas of parts made of any corrosion resistant steel or alloy when not coated all over, and to parts made of any steel when thickness specified is less than 0.0002 inch (5 m). 3.4Quality
35、: Cadmium deposit, as received by purchaser, shall be smooth, continuous, adherent to basis metal, uniform in appearance, and essentially free from pinholes, porosity, blisters, nodules, pits, and other imperfections detrimental to usage of the coating. Slight staining or discoloration is permissibl
36、e. 3.4.1The cadmium deposit shall show no indication of contamination or improper operation of equipment used to produce the coating, such as powdery or darkened coatings. Copyright SAE International Provided by IHS under license with SAELicensee=Defense Supply Ctr/5913977001 Not for Resale, 12/04/2
37、007 20:25:15 MSTNo reproduction or networking permitted without license from IHS -,-,- AMS 2426DSAEAMS 2426D - 5 - 4.QUALITY ASSURANCE PROVISIONS: 4.1Responsibility for Inspection: The processor shall supply all samples for processors tests and shall be responsible for the performance of all require
38、d tests. Parts, when required for test, shall be supplied by purchaser. Purchaser reserves the right to sample and to perform any confirmatory testing deemed necessary to ensure that processing conforms to the requirements of this specification. 4.2Classification of Tests: 4.2.1Acceptance Tests: Thi
39、ckness (3.3.1), adhesion (3.3.2), and quality (3.4) are acceptance tests and shall be performed on each lot. 4.2.2Periodic Tests: Corrosion-resistance (3.3.3) and tests of equipment and process controls to ensure that the deposited metal will conform to the specified requirements are periodic tests
40、and shall be performed at a frequency selected by the processing vendor unless frequency of testing is specified by purchaser. 4.2.3Preproduction Tests: All technical requirements are preproduction tests and shall be performed prior to or on the initial shipment of each part number to a purchaser, w
41、hen a change in material and/or processing requires approval by the cognizant engineering organization (See 4.4.2), and when purchaser deems confirmatory testing to be required. 4.3Sampling and Testing: Shall be as follows; a lot shall be all parts of the same part number, cleaned and pretreated as
42、applicable at the same time in the same equipment, and coated in a single pump-down, and presented for processors inspection at one time: 4.3.1Acceptance Tests: Number of parts sampled for acceptance testing shall be not less than shown in Table 2. TABLE 2 - Sampling for Acceptance Testing Number of
43、 Parts in LotQuality Thickness and Adhesion Up to 7 8 to 15 16 to 40 41 to 110 111 to 300 301 to 500 501 to 700 701 to 1200 Over 1200 all 7 10 15 25 35 50 75 125 3 if available 4 4 5 6 7 8 10 15 Copyright SAE International Provided by IHS under license with SAELicensee=Defense Supply Ctr/5913977001
44、Not for Resale, 12/04/2007 20:25:15 MSTNo reproduction or networking permitted without license from IHS -,-,- AMS 2426DSAEAMS 2426D - 6 - 4.3.2Periodic Tests: Sample quantities and frequency of testing shall be at the discretion of the processor unless otherwise specified by the purchaser. 4.3.2.1Fo
45、r corrosion-resistance tests, specimens shall be panels of low-carbon or low-alloy steel. 4.4Approval: 4.4.1The process and control factors, a preproduction sample part, or any combination thereof, shall be approved by the cognizant engineering organization before production parts are supplied. 4.4.
46、2The processor shall make no significant changes to materials, processes, or control factors from those on which approval was based unless the change is approved by the cognizant engineering organization. A significant change is one which, in the judgment of the cognizant engineering organization, w
47、ould affect the properties or performance of the part. 4.4.3Control factors for the process shall include, but not be limited to, the following: Method(s) of surface preparation Source and form of cadmium Method of cadmium vaporization Electrical parameters (current and/or voltage limits) Vacuum lev
48、el Composition of conversion coating and parameters for application Fixturing techniques Location and orientation of parts during coating Temperature limits of parts during coating Periodic test plan. 4.5Reports: The processor of coated parts shall furnish with each shipment a report stating that th
49、e parts have been processed and tested in accordance with the specified requirements and that they conform to the acceptance test requirements. This report shall include the purchase order number, lot number, AMS 2426D, part number, and quantity. 4.6Resampling and Retesting: 4.6.1If results of any acceptance tes