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 there
2、from, 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 2010 SAE International All rights reserved. No part of this publication m
3、ay 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: +1 724-776-4970 (outside U
4、SA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/AMS2477A AEROSPACE MATERIAL SPECIFICATION AMS2477 REV. A Issued 2005-02 Revised 2010-04 Super
5、seding AMS2477 Conversion Coating for Aluminum Alloys Low Electrical Resistance Coating RATIONALE AMS2477A results from a Five Year Review and update of this specification. 1. SCOPE 1.1 Purpose This specification covers the requirements for a low-electrical-resistance chemical conversion coating on
6、aluminum and aluminum alloy parts. 1.2 Application This process has been used typically to provide aluminum with a thin inorganic film that improves corrosion resistance and adhesion of organic coatings and possesses low electrical resistance, but usage Is not limited to such applications. 1.3 Safet
7、y - 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 address the hazards which may be involved in such use. It is the responsibility of the user to ensur
8、e 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. 2. APPLICABLE DOCUMENTS The issue of the following documents in effect on the date of the purchase order forms a part of this
9、specification to the extent specified herein. The supplier may work to a subsequent revision of a document unless a specific document issue is specified. When the referenced document has been cancelled and no superseding document has been specified, the last published issue of that document shall ap
10、ply. 2.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. AMS4027 Aluminum Alloy, Sheet and Plate, 1.0Mg - 0.60Si - 0.28Cu - 0.20Cr (6061; -T6 Sheet, -T651 Plate
11、), Solution and Precipitation Heat Treated SAE AMS2477A Page 2 of 6 2.2 ASTM Publications Available from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshocken, PA 15248-2959, Tel: 610-832-9585, www.astm.org. ASTM B 117 Operating Salt Spray (Fog) Apparatus ASTM D 3359 Test Methods
12、 for Measuring Adhesion by Tape Test 2.3 U.S. Government Publications Available from the Document Automation and Production Service (DAPS), Building 4/D, 700 Robbins Avenue, Philadelphia, PA 19111-5044, Tel: 215-697-6257, http:/assist.daps.dla.mil/quicksearch/. MIL-PRF-23377 Primer Coatings: Epoxy H
13、igh-Solids MIL-P-53022 Primer, Epoxy Coating, Corrosion Inhibiting, Lead and Chromate Free MIL-P-53030 Primer Coating, Epoxy, Water Reducible, Lead and Chromate Free MIL-PRF-85582 Primer Coatings: Epoxy, Waterborne 3. TECHNICAL REQUIREMENTS 3.1 Preparation 3.1.1 Location of racking points shall be o
14、n areas not to be coated or where acceptable to the cognizant engineering organization. 3.1.2 The coating shall be applied over a surface free from water breaks. The cleaning procedure shall not produce pitting or intergranular attack of the basis metal and shall preserve dimensional requirements. S
15、ee 8.5. 3.2 Procedure 3.2.1 The application process shall consist of immersion, spray, pen, or brush (swab) application of a solution capable of generating a coating compliant with the requirements of this specification. See 8.6. 3.2.2 Touchup Unless otherwise specified by the cognizant engineering
16、organization, areas from which the coating has been removed may be touched up provided the area touched-up does not exceed 5 percent of the total surface area of the part. 3.3 Properties Coated surfaces shall conform to the following requirements: 3.3.1 Electrical contact resistance of the coated pr
17、oduct shall not exceed 0.005 ohm (5 milliohm) per square inch when tested in accordance with a procedure acceptable to the cognizant engineering organization See 8.11. 3.3.2 Corrosion Resistance The basis metal shall not show evidence of corrosion beyond the limits specified below after exposure to
18、168 hours 1 to salt spray corrosion testing in accordance with ASTM B 117 with the exposed surface of test panels inclined back approximately 6 degrees from vertical. 3.3.2.1 No specimen shall show more than five isolated spots or pits, none larger than 1/32 inch (0.79 mm) in diameter. Areas within
19、0.25 inch (6.4 mm) from the edges, identification markings, and racking points shall be excluded. Loss of color shall not be cause for rejection. See 8.8. SAE AMS2477A Page 3 of 6 3.3.2.2 No more than 15 isolated spots or pits, none larger than 1/32 inch (0.79 mm) in diameter, on the combined surfac
20、e area of all five test panels. See 8.8. 3.3.2.3 Electrical contact resistance after salt fog exposure shall not exceed 0.010 ohm (10 milliohm) per square inch when tested in accordance with a procedure acceptable to the cognizant engineering organization. See 8.11. 3.3.3 Color Coating shall be any
21、distinctive color that distinguishes coated from the uncoated items. See 8.9. 3.3.4 Primer Adhesion Primer in accordance with MIL-P-53022, MIL-P-53030, MIL-PRF-23377, or MIL-PRF-85582 applied over the conversion coating and cured in accordance with manufacturers instructions shall show no separation
22、 between the primer and the conversion coating when tested in accordance with ASTM D 3359 dry tape method 3.4 Quality 3.4.1 The coating, as received by purchaser, shall be continuous, adherent to basis metal, and visually free from powdery residue, pin holes, pits, and other imperfections detrimenta
23、l to usage of the parts. Appearance shall be uniform although slight variations in color are permissible. 4. QUALITY ASSURANCE PROVISIONS 4.1 Responsibility for Inspection The processor shall supply all samples for processors tests and shall be responsible for performance of all required tests. When
24、 parts are to be tested, the parts shall be supplied by purchaser. The cognizant engineering organization reserves the right to sample and to perform any confirmatory testing deemed necessary to ensure that processing conforms to specified requirements. 4.2 Classification of Tests 4.2.1 Acceptance T
25、ests Color (3.3.3) and quality (3.4) are acceptance tests and shall be performed on parts, or samples representing parts when permitted, from each lot. See 4.3.3. 4.2.2 Periodic Tests Corrosion resistance (3.3.2) and primer adhesion (3.3.4) are periodic tests and shall be performed monthly unless fr
26、equency of testing is specified by the cognizant engineering organization. Tests of cleaning and coating solutions are periodic tests and shall be performed at a frequency established by the processor unless frequency of testing is specified by the cognizant engineering organization. See 8.4. 4.2.2.
27、1 Periodic testing may be suspended in any month when parts are not processed, however, preproduction testing may be required by the cognizant quality organization upon resumption of processing. 4.2.3 Preproduction Tests All property verification tests (section 3.3) are preproduction tests shall be
28、performed prior to production and when the cognizant engineering organization deems confirmatory testing to be required. SAE AMS2477A Page 4 of 6 4.3 Sampling for Testing 4.3.1 Acceptance Tests Test samples shall be randomly selected from all parts in the lot. A lot shall be all parts of the same pa
29、rt number coated in the same set of solutions in each consecutive 24 hours of operation, and presented for processors inspection at one time. Unless the cognizant engineering organization provides a sampling plan, the minimum number of samples shall be as shown in Table 1. TABLE 1 - Sampling For Acc
30、eptance Tests Number of Parts in Lot Quality and Color up to 6 All 7 to 15 7 16 to 40 10 41 to 110 15 111 to 300 25 301 to 500 35 501 to 700 50 701 to 1200 75 over 1200 125 4.3.2 Periodic Tests Five test panels are required for corrosion resistance tests. Two test panels are required for primer adhe
31、sion tests. 4.3.3 Sample Configuration 4.3.3.1 AMS4027 (6061-T6) test panels for corrosion and electrical resistance testing shall be cleaned and processed with parts. Dimensions, number of test panels, and number and location of readings shall be in accordance with the test procedure. See 3.3.1. 4.
32、4 Approval 4.4.1 The process and control factors or a preproduction part, or both, whichever is specified, shall be approved by the cognizant engineering organization before production parts are supplied. 4.4.2 If the processor makes a significant change to any material, process, or control factor f
33、rom that which was used for process approval, all preproduction tests shall be performed and the results submitted to the cognizant engineering organization for process reapproval unless the change is approved by the cognizant engineering organization. A significant change is one which, in the judgm
34、ent of the cognizant engineering organization, could affect the properties or performance of the parts. 4.4.3 Control factors shall include, but not be limited to the following: Surface preparation and cleaning methods Coating material trade name and manufacturer Coating bath composition and composi
35、tion control limits Coating bath temperature limits and controls Primer application and adhesion test procedure Electrical contact resistance test procedure Stripping procedure, when applicable Periodic test plan for cleaning and processing solutions. See 8.4. SAE AMS2477A Page 5 of 6 4.5 Reports Th
36、e processor shall furnish with each shipment a report stating that the 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, AMS2477A, part number, and quantit
37、y. 4.6 Resampling and Retesting 4.6.1 If any acceptance test fails to meet specified test requirements, the parts in that lot may be stripped, pretreated, coated, and post treated as defined herein and retested. Alternatively, all parts in the lot may be inspected for the nonconforming attribute, an
38、d the nonconforming parts may be stripped, pretreated, coated, and post treated as defined herein, and retested. After stripping and recoating, parts shall meet the dimensions on the drawing. 4.6.1.1 When stripping is performed, the method shall be acceptable to the the cognizant engineering organiz
39、ation and shall not roughen, pit, or embrittle the basis metal or adversely affect part dimensions. When parts have been stripped and recoated, the purchaser shall be informed. 4.6.2 If any periodic test fails to meet specified test requirements, the process is nonconforming. No additional parts sha
40、ll be coated until the process is corrected and new specimens are coated and tested. Results of all tests shall be recorded and, when requested, reported. Purchasers shall be notified of all parts coated since the last acceptable test. 5. PREPARATION FOR DELIVERY 5.1 Parts shall be handled and packa
41、ged in such a manner as will ensure that the required physical characteristics and properties of the coating are preserved. 5.2 Packages of coated parts shall be prepared for shipment in accordance with commercial practice and in compliance with applicable rules and regulations pertaining to the han
42、dling, packaging, and transportation of the parts to ensure carrier acceptance and safe delivery. 6. ACKNOWLEDGMENT The processor shall mention AMS2477A in all quotations and when acknowledging purchase orders. 7. REJECTIONS Parts on which coating does not conform to this specification or to modific
43、ations authorized by the cognizant engineering organization will be subject to rejection. 8. NOTES 8.1 The change bar (|) located in the left margin is for convenience of the user in locating areas where technical revisions, not editorial changes, have been made to the previous issue of this documen
44、t. An (R) symbol to the left of the document title indicates a complete revision of the document including technical revisions, change bars and (R) are not used in original publications, nor in documents that contain editorial changes only. 8.2 Part manufacturing operations, such as heat treatment,
45、forming, joining, and media finishing, can affect the condition of the substrate, or, if performed after coating, could adversely affect the coating. Achieving a durable, low-electrical-resistance assembled bond joint typically requires removal of all coatings down to bare aluminum, brush applicatio
46、n of the conversion coating to a specific contact area, drying, and sealing of the joint. The sequencing of operations and the maximum joint resistance should be specified by the cognizant engineering organization and is not controlled by this specification. SAE AMS2477A Page 6 of 6 8.3 The parts ma
47、nufacturer should ensure that the surfaces of the metal parts supplied to the processor are free from blemishes, pits, tool marks, and other irregularities that will affect the quality of the finished parts. Defects and variations in appearance that arise from surface conditions of the substrate, su
48、ch as porosity, scratches, or inclusions, that persist in the coating despite the observance of accepted industry practices shall not be cause for rejection. 8.4 ARP4992, Periodic Test Plan for Process Solutions, is recommended to satisfy the requirements for the control of processing solutions. 8.5
49、 A commercial deoxidizer is typically used to produce a clean, slightly etched surface. Alkaline etching can result in intergranular attack. Alkaline residues should be removed by thorough rinsing in order to extend the life of the deoxidizer and/or conversion coating solution. 8.6 The coating raw material is typically supplied in powder form by a specialty chemical firm which provides mixing and operating instructions. 8.7 Exp
