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 revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2017 SAE International All rights reserved. No part of this p
3、ublication may 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: +1 724-776-497
4、0 (outside USA) 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:/standards.sae.org/AMS2428 AEROSPACE MATERIAL SPECIFICATION AMS2428 Issued 2017-07 Plating, Cobalt-Phosphorus, Nan
5、ocrystalline RATIONALE A wear and corrosion resistant coating that can be used for repair and OEM applications as a suitable alternative to electrodeposited hard chromium. NOTICE ORDERING INFORMATION: The following information shall be provided to the plating processor by the purchaser: 1. Purchase
6、order shall specify not less than the following: AMSXXXX Plating thickness desired (see 3.4.1.3) Basis metal to be plated Tensile strength or hardness of the basis metal Preplate stress relief to be performed by plating processor (time and temperature) if different from 3.1.1 Special features, geome
7、try or processing present on parts that requires special attention by the plating processor Hydrogen embrittlement relief to be performed by plating processor (parameters or reference document) if different from 3.3.1 Minimum thickness on internal surfaces, if required (see 3.4.1.2) Quantity of piec
8、es to be plated 2. Parts manufacturing operations such as heat treating, forming, joining and media finishing can affect the condition of the substrate for plating, or if performed after plating, could adversely affect the plated part. The sequencing of these types of operations should be specified
9、by the cognizant engineering organization or purchaser and is not controlled by this specification, except as noted herein. SAE INTERNATIONAL AMS2428 Page 2 of 8 1. SCOPE 1.1 Purpose This specification covers the requirements for electrodeposited nanocrystalline cobalt-phosphorus plating. 1.2 Applic
10、ation This plating is typically used on parts for increasing corrosion resistance, increasing wear resistance and reconditioning worn or undersized parts, but usage is not limited to such applications. 1.3 Safety - Hazardous Materials While the materials, methods, applications, and processes describ
11、ed or referenced in this specification may involve the use of hazardous materials, this specification does not address the hazards that 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 nec
12、essary 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 specification to the extent specified herein. The supplier may work to a subsequent r
13、evision 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 apply. 2.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, W
14、arrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or +1 724-776-4970 (outside USA), www.sae.org. AMS2453 Low Stress Grinding of Steel Parts Heat Treated to 180 ksi or Over, and Low Stress Grinding of Chrome Plating Applied to Steel Parts Heat Treated to 180 ksi or Over AMS2750 Pyro
15、metry AMS2759/9 Hydrogen Embrittlement Relief (Baking) of Steel Parts ARP1917 Clarification of Terms Used in Aerospace Metals Specifictions 2.2 ASTM Publications Available from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, Tel: 610-832-9585, www.astm.org
16、. ASTM B117 Operating Salt Spray (Fog) Apparatus ASTM B242 Preparation of High-Carbon Steel for Electroplating ASTM B253 Preparation of Aluminum Alloys for Electroplating ASTM B322 Cleaning Metals Prior to Electroplating ASTM B374 Standard Terminology Relating to Electroplating ASTM B487 Measurement
17、 of Metal and Oxide Coating Thicknesses by Microscopical Examination of a Cross Section ASTM B504 Measurement of Thickness of Metallic Coatings by the Coulometric Method SAE INTERNATIONAL AMS2428 Page 3 of 8 ASTM B568 Measurement of Coating Thickness by X-Ray Spectrometry ASTM B571 Qualitative Adhes
18、ion Testing of Metallic Coatings ASTM B578 Microhardness of Electroplated Coatings ASTM B748 Measurement of Thickness of Metallic Coatings by Measurement of Cross Section with a Scanning Electron Microscope ASTM F519 Mechanical Hydrogen Embrittlement Evaluation of Plating/Coating Processes and Servi
19、ce Environments 3. TECHNICAL REQUIREMENTS 3.1 Preparation 3.1.1 Stress Relief Treatment 3.1.1.1 All steel parts having a hardness of 40 HRC and above and that are machined, ground, cold formed or cold straightened after heat treatment shall be cleaned to remove surface contamination and thermally st
20、ress relieved before plating. (Residual tensile stresses have been found to be damaging during electrofinishing.) Furnaces used for stress relief shall be controlled per AMS2750; the minimum requirements shall be Class 5, with Type D instrumentation. Temperatures to which parts are heated shall be s
21、uch that stress relief is obtained while still maintaining hardness of parts within drawing limits. Unless otherwise specified, the following treatment temperatures and times shall be used: 3.1.1.1.1 For parts, excluding nitrided parts, having a hardness of 55 HRC and above, and for carburized and i
22、nduction hardened parts, stress relieve at 275 F 25 (135 C 14) for 5 to 10 hours. 3.1.1.1.2 For parts having a hardness less than 55 HRC, and for nitrided parts, stress relieve at 375 F 25 (191 C 13) for a minimum of 4 hours. Higher temperatures shall be used only when specified or approved by the c
23、ognizant engineering organization. 3.1.1.1.3 For peened parts: If stress relief temperatures above 375 F (191 C) are elected, the stress relieve shall be performed prior to peening or the cognizant engineering organization shall be consulted and shall approve the stress relief temperature. 3.1.2 Cle
24、anliness Parts shall have clean surfaces, free of water break, prior to immersion in the plating solution. The cleaning procedure shall not produce pitting or intergranular attack of the basis metal and shall preserve dimensional requirements. Mechanical surface preparation, such as a dry or wet abr
25、asive blast, if employed, shall be completed prior to application of a nickel strike, when used, and shall be accomplished in a manner that will not affect the appearance or quality of the finished part. Metal parts may be cleaned in accordance with ASTM B242, ASTM B253 or ASTM B322. 3.1.3 Electrica
26、l Contact Points For parts which are to be plated all over, location of electrical contact points shall be acceptable to purchaser. For parts which are not to be plated all over, location shall be in areas on which plating is not required. 3.2 Procedure 3.2.1 Parts shall be plated by electrodepositi
27、on of a cobalt-phosphorus alloy plating onto a properly prepared surface. 3.2.1.1 On magnesium, aluminum and corrosion-resistant steels or similarly passive materials, a preliminary chemical coating, immersion plate, or metal flash acceptable to the cognizant engineering organization is permissible.
28、 SAE INTERNATIONAL AMS2428 Page 4 of 8 3.3 Hydrogen Embrittlement Relief Treatment of steel parts shall be in accordance with AMS2759/9. 3.4 Properties 3.4.1 Thickness If not specified, the minimum thickness shall be 0.002 inch (51m) determined in accordance with ASTM B487, ASTM B504, ASTM B568, AST
29、M B748 or other method acceptable to purchaser. 3.4.1.1 All surfaces of the part, except those which cannot be touched by a sphere 0.75 inch (19 mm) in diameter, shall be plated to the specified thickness. Unless otherwise specified, surfaces such as holes, recesses, threads and other areas where a
30、controlled deposit cannot be obtained under normal plating conditions, may be under the specified limit provided they show visual plating coverage. The plate shall be substantially uniform in thickness on significant surfaces except that build-up at exterior corners or edges shall be permitted provi
31、ded finished drawing dimensions are met. 3.4.1.2 For surfaces that will not be machined after plating, the plate shall be substantially uniform in thickness on significant surfaces except that slight buildup on exterior corners or edges will be permitted provided finished drawing dimensions are met.
32、 3.4.1.3 For selective plating, specific areas to be plated shall be as specified on the engineering drawing. 3.4.1.3.1 The engineering drawing shall specify if any internal surfaces are required to be plated to a thickness requirement. 3.4.2 Hardness Hardness shall be not lower than 510 HV100, or e
33、quivalent, determined in accordance with ASTM B578. For parts with deposits less than 0.002 inch (51 m) in thickness, separate specimens may be utilized with cobalt-phosphorus plating sufficiently thick to allow valid microhardness tests to be performed. 3.4.3 Adhesion Shall conform to one of the fo
34、llowing: 3.4.3.1 Adhesion shall meet the requirements of ASTM B571 Bend Test method with the specimen bent repeatedly back and forth through an angle of 180 until failure of the basis metal occurs. Examine the region at low magnification for separation, for example, 10X, for separation or peeling of
35、 the coating. Formation of crack that do not result in flaking or blistering of the plate is acceptable. 3.4.3.2 Adhesion of plating after finish machining of the plating will be considered acceptable evidence of plating adhesion. 3.4.3.3 There shall be no blisters or other evidence of poor adhesion
36、 when parts are subjected to the heat-quench test of ASTM B571. 3.4.4 Corrosion Resistance Carbon and low-alloy steel parts when required by purchaser, or test specimen, shall show no visual evidence of corrosion after being subjected for not less than 200 hours to a continuous salt spray corrosion
37、test conducted in accordance with ASTM B117. 3.4.5 Hydrogen Embrittlement The plating process after baking shall not cause embrittlement in steel parts 36 HRC and over determined in accordance with 4.3.3.4. SAE INTERNATIONAL AMS2428 Page 5 of 8 3.5 Quality The deposits shall be smooth, adherent, and
38、 free from visible blisters, pits, porosity, cracks and other defects. The plating shall show no indication of contamination or improper operation of equipment used to produce the deposit, such as excessively powdered or darkened plating, build-up and other defects. The size and number of contact ma
39、rks shall be at a minimum, consistent with good practice. The location of contact marks shall be in areas of minimum exposure to service environmental conditions where important to the function of the part. Superficial staining, which has been demonstrated as resulting from rinsing, or slight discol
40、oration resulting from baking operations to relieve hydrogen embrittlement, as specified above (see paragraph 3.3), shall not be cause for rejection. All details of workmanship shall conform to the best practice for high quality plating. 4. QUALITY ASSURANCE PROVISIONS 4.1 Responsibility for Inspect
41、ion The processor shall supply all specimens for processor tests and shall be responsible for the performance of all required tests. When parts or special specimens are to be tested, the parts shall be supplied by purchaser. The cognizant engineering organization reserves the right to sample and to
42、perform any confirmatory testing deemed necessary to ensure that processing conforms to specified requirements. 4.2 Classification of Tests 4.2.1 Acceptance Tests: Thickness (3.4.1), hardness (3.4.2), adhesion (3.4.3), and quality (3.5) are acceptance tests and shall be performed on parts, or specim
43、ens representing parts when permitted herein (see 4.3.3), from each lot. 4.2.2 Periodic Tests: Corrosion resistance (3.4.4) is a periodic test and shall be performed at least quarterly unless frequency of testing is specified by the cognizant engineering organization. Hydrogen embrittlement (3.4.5)
44、is a periodic test and shall be performed in accordance with 4.3.3.4. at least once in each month that steel parts 36 HRC and over are plated unless frequency of testing is specified by the cognizant engineering organization. Tests of cleaning and plating solutions are periodic tests and shall be pe
45、rformed at a frequency established by the processor unless frequency of testing is specified by the cognizant engineering organization (see 4.4.3 and 8.8). 4.2.3 Preproduction tests: All technical requirements are preproduction tests and shall be performed prior to or on the initial shipment of plat
46、ed parts to a purchase, when a change in material and/or processing requires reapproval by the cognizant engineering organization (see 4.4.2), and when purchaser deems confirmatory testing to be required. 4.2.4 The processor shall maintain a record of each processing bath, showing all additions of c
47、hemicals or treatments to the bath, the results of all tests and chemical analysis performed, and the quantity of parts plated during operation. These records shall be maintained and made available for review for not less than one year after completion of the contract or purchase order. 4.3 Sampling
48、 for Tests Sampling for testing shall not be less than the following; a lot shall be all parts of the same part number, plated to the same range of plate thickness in the same set of solutions, in each consecutive 24 hour period of operation, and presented for processors inspection at one time: 4.3.
49、1 Acceptance Tests: Test specimens shall be selected randomly from all parts in the lot. Unless the cognizant engineering organization supplies a sampling plan, the minimum number of specimens shall be as shown in Table 1. SAE INTERNATIONAL AMS2428 Page 6 of 8 Table 1 - Sampling for acceptance tests Number of Parts in Lot Quality Thickness and Adhesion Hardness Up to 7 All 3 or all* 1 8 to 15 7 4 1 16 t
