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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: CustomerServicesae.org SAE WEB ADDRESS:http:/www.sae.org Electrolytic Treatment for Magnesium Alloys Alkaline Type, Full Coat 1.SCOPE: 1.1Purpose: This specification establishes the engineering requirements for producing anodic coatings on magnesium and magnesium alloys, from
5、an alkaline electrolyte, and the properties of those coatings. 1.2Application: This coating has been used typically to increase corrosion and abrasion resistance and to provide surfaces which will improve paint adhesion, but usage is not limited to such applications. 1.2.1The process is applicable t
6、o all cast and wrought magnesium alloys, after proper allowances are made for dimensional changes intrinsic to the process, but should not be employed on parts which are subject to flexure. 1.3Safety - Hazardous Materials: While the materials, methods, applications, and processes described or refere
7、nced 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 sole responsibility of the user to ensure familiarity with the safe and proper use of any hazardous materials and to take necessary prec
8、autionary 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 revision of
9、a document unless a specific document issue 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. AEROSPACE MATERIAL SPECIFICATION AMS 2476C Issued1957-09 Revised2003-01 Reaffirmed2007-11 Su
10、perseding AMS 2476B Copyright SAE International Provided by IHS under license with SAELicensee=MHI - NAGOYA related to 3944000/3944000013 Not for Resale, 01/23/2008 22:09:19 MSTNo reproduction or networking permitted without license from IHS -,-,- AMS 2476CSAEAMS 2476C - 2 - 2.1ASTM Publications: Av
11、ailable from ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959 or www.astm.org. ASTM B 244Measurement of Thickness of Anodic Coatings on Aluminum and of Other Nonconductive Coatings on Nonmagnetic Basis Metals with Eddy-Current Instruments ASTM B 487Measurement of Metal and Oxide Coating
12、 Thicknesses by Microscopical Examination of a Cross Section 3.TECHNICAL REQUIREMENTS: 3.1Solutions: 3.1.1Electrolyte: Shall be an aqueous solution of the composition shown in Table 1. Variations in solution composition may be used provided the coating meets the requirements of 3.4. 3.1.1.1The solut
13、ion temperature shall be maintained at a 70 to 86 F (21 to 30 C). 3.1.2The post treatment solution shall be as shown in Table 2. 3.1.2.1The solution shall be used at room temperature. 3.2Preparation: Prior to coating, parts shall be cleaned in a suitable alkaline solution to provide a water-break-fr
14、ee surface. Cathodic, direct current may be used to reduce cleaning time. Following cleaning, parts shall be rinsed in cold flowing water. TABLE 1 - Coating Electrolyte Composition IngredientsOunces/GallonGrams/Liter Potassium Hydroxide16.0 to 24.0120 to 180 Aluminum Hydroxide (dried gel) Al (OH)3 4
15、.0 to 5.0 30 to 37 Potassium Fluoride 4.0 to 5.0 30 to 37 Trisodium Phosphate 4.0 to 5.0 30 to 37 Potassium Permanganate 2.0 to 3.0 15 to 22 TABLE 2 - Post Treatment Solution Composition IngredientsOunces/GallonGrams/Liter Sodium Dichromate 2.5 to 3.019 to 22 Ammonium Bifluoride13.0 to 13.597 to 101
16、 Copyright SAE International Provided by IHS under license with SAELicensee=MHI - NAGOYA related to 3944000/3944000013 Not for Resale, 01/23/2008 22:09:19 MSTNo reproduction or networking permitted without license from IHS -,-,- AMS 2476CSAEAMS 2476C - 3 - 3.3Procedure (See 8.2): 3.3.1Parts shall be
17、 firmly attached to the racks. Contact areas shall be kept to minimum size and, when practical, shall be on surfaces not required to be coated. When parts are to be coated all over, electrical contact shall be on areas indicated on the drawing. 3.3.2Parts shall be distributed equally on the electrod
18、es so that surface area of each group is approximately the same. 3.3.3Parts shall be hung to minimize trapped gas or air. 3.3.4Alternating current shall be applied and voltage raised manually or automatically to maintain a current density of 15 to 30 amperes/square foot (161 to 323 A/m2), based on t
19、otal area exposed immersed metal. Completion of coating is indicated by a minimum of 85 volts across the work and a uniform brown color free from definite light areas on the parts when examined wet after a water rinse. 3.3.5Immediately following coating and rinsing, the parts shall be immersed in th
20、e solution shown in Table 2, held for 40 to 50 seconds, drained, and dried without rinsing. 3.3.6Parts which have been coated and post treated shall be aged for four to six hours at 175 F 10 (79 C 6) and 85% 5 relative humidity. Moisture condensation on the parts shall be avoided. 3.4Properties: Coa
21、ted parts shall conform to the following requirements: 3.4.1Thickness: Dimensional increase resultant from coating shall be 0.0013 to 0.0017 inches (33 to 43 m), determined in accordance with 4.4.1. 3.4.2Coating Weight: If the dimensional change as a result of anodic coating cannot be determined acc
22、urately because of irregular shape of parts, determination of coating weight may be used as an alternative for dimensional change requirement. Coating weight shall be 5.2 to 6.8 grams/square foot (56 to 73 grams/m2), determined in accordance with 4.4.2. 3.4.3Abrasion Resistance: Specimens, tested in
23、 accordance with 4.4.3, shall not exhibit scratches which penetrate to the basis metal. 3.5Quality: Coating, as received by purchaser, shall be continuous, smooth, adherent, and uniform in appearance, and shall be free from powdery areas, loose film, discontinuities such as breaks or scratches, exce
24、pt at contact points, or other damage or imperfections detrimental to usage of the coating. Copyright SAE International Provided by IHS under license with SAELicensee=MHI - NAGOYA related to 3944000/3944000013 Not for Resale, 01/23/2008 22:09:19 MSTNo reproduction or networking permitted without lic
25、ense from IHS -,-,- AMS 2476CSAEAMS 2476C - 4 - 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 required tests. Purchaser reserves the right to sample and to perform any
26、confirmatory testing deemed necessary to ensure that processing conforms to the requirements of this specification. 4.2Classification of Tests: 4.2.1Acceptance Tests: Thickness (3.4.1) or coating weight (3.4.2) and quality (3.5) are acceptance tests and shall be performed on each lot. 4.2.2Periodic
27、Tests: Abrasion resistance (3.4.3) and tests of cleaning and processing solutions (See 8.4) to ensure that the coating will conform to specified requirements are periodic tests and shall be performed at a frequency selected by the processor unless frequency of testing is specified by purchaser. 4.2.
28、3Preproduction Tests: All technical requirements are preproduction tests and shall be performed prior to or on the initial shipment of processed parts to a purchaser, when a change in material and/ or processing requires reapproval by the cognizant engineering organization (See 4.5.2), and when purc
29、haser 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, processed in the same solutions in not longer than eight consecutive hours and presented for processors inspection at one time: 4.3.1For Acceptance Tests:
30、As shown in Table 3. 4.3.2For Periodic Tests: Sample quantity and frequency shall be selected at the discretion of the processor, unless otherwise specified. TABLE 3 - Sampling for Acceptance Testing Number of Parts in LotQuality Thickness or Coating Weight Up to 7 8 to 15 16 to 40 41 to 110 111 to
31、300 301 to 500 Over 500 All 7 10 15 25 35 50 3 4 4 5 6 7 8 Copyright SAE International Provided by IHS under license with SAELicensee=MHI - NAGOYA related to 3944000/3944000013 Not for Resale, 01/23/2008 22:09:19 MSTNo reproduction or networking permitted without license from IHS -,-,- AMS 2476CSAEA
32、MS 2476C - 5 - 4.4Test Methods: Tests shall be performed on actual parts, whenever possible. Nondestructive test methods shall be selected wherever practical and where permitted by the specification. When destructive tests are required and coated parts are of a configuration or value as to be imposs
33、ible, impractical, or uneconomical to test, separate specimens cleaned, coated, and post treated with the parts represented may be used. Specimen composition shall be generically similar to that of the parts represented. Specimens for determination of coating weight (3.4.2) shall have a total surfac
34、e area of not less than 24 square inches (156 cm2). 4.4.1Coating Thickness: Shall be determined on parts or representative specimens by direct micrometer measurement or in accordance with ASTM B 244, ASTM B 487, or other method acceptable to purchaser. Micrometer measurements shall be calibrated aga
35、inst microscopic measurements on specimens of the same alloy processed to the same nominal coating thickness as the parts. Micrometers shall have an accuracy of 0.0001 inch (2.5 m). If specimens are used, they shall be uniformly distributed throughout the lot and processed with the parts they repres
36、ent. 4.4.1.1When the direct micrometer method is used to determine coating thickness, it is necessary to divide the dimensional increase by two, if both sides of the part or specimen are coated, and multiply the resultant number by 1.3 to establish the true coating thickness. The correction is neces
37、sary because the coating process not only removes basis metal but also deposits an anodic film. 4.4.2Coating Weight: Parts or specimens shall be weighed and the value recorded (W1). Immerse the specimens in an aqueous solution containing 300 grams/liter, chemically pure, sulphate-free chromic acid,
38、heated to 120 F 5 (49 C 3), and hold for ten minutes. During the stripping operation, maintain a strip of commercially pure aluminum in the bath to minimize the loss of magnesium metal. Prevent contact between the aluminum strip and the magnesium specimen. Remove the specimen from the strip solution
39、, rinse, thoroughly dry, and reweigh (W2). Repeat the stripping operation using a five minute immersion period, rinsing, drying, and weighing each time the specimen is removed from stripping solution. Stripping is considered complete when the weight difference between subsequent weighings is not mor
40、e than 1.0 milligram per square inch (0.155 mg/cm2). Calculate the coating weight using Equation 1. (Eq. 1) where: W1= Initial weight of coated specimen W2= Weight of stripped specimen A= Total area of specimen 4.4.3Abrasion Resistance: Place an anodized panel on a flat surface and wet the exposed s
41、urface. Using a 3/16 inch (4.8 mm) diameter, fire polished pyrex glass rod, rub the surface of the specimen using a one inch (25 mm) reciprocal motion, applying enough pressure on the glass rod to cause abrasion of the fire polished surface of the rod. When the glass rod exhibits an abraded surface,
42、 examine the surface of the specimen. The surface of the specimen shall not show evidence of scratches which penetrate to the basis metal. grams/square foot W1W2 A - -= Copyright SAE International Provided by IHS under license with SAELicensee=MHI - NAGOYA related to 3944000/3944000013 Not for Resal
43、e, 01/23/2008 22:09:19 MSTNo reproduction or networking permitted without license from IHS -,-,- AMS 2476CSAEAMS 2476C - 6 - 4.5Approval: 4.5.1The process control procedures, a preproduction sample, or both, whichever is specified, shall be approved by the cognizant engineering organization before p
44、roduction parts are supplied. 4.5.2Processor of coated parts shall make no significant change in bath, materials, processes, or control factors from those on which the approval was based, unless the change is approved by the cognizant engineering organization. A significant change is one which, in t
45、he judgment of the cognizant engineering organization, could effect the properties or performance of the coating. 4.5.3Control factors shall include, but not be limited to, the following: Surface preparation and cleaning procedures Coating bath composition limits Racking setup Temperature limits of
46、coating bath Current/voltage limits and controls Post treatment time and temperature Coating thickness measurement method Periodic test plan. 4.6Reports: The processing vendor shall furnish with each shipment a report stating that the parts have been processed in accordance with specified requiremen
47、ts and that they conform to the technical requirements. This report shall include the purchase order number, lot number, AMS 2476C, part number, and quantity. 4.7Resampling and Retesting: 4.7.1If any lot acceptance test fails to meet specified requirements, parts in that lot may be stripped by a met
48、hod acceptable to purchaser that does not roughen, pit or embrittle the basis metal or adversely affect part dimensions, pretreated, coated, post-treated as defined herein and tested. Alternatively, all parts in the lot may be inspected for the nonconforming attribute, and the nonconforming parts ma
49、y be stripped by a method acceptable to purchaser that does not pit, roughen, embrittle the basis metal, or adversely affect the part dimensions, pretreated, coated, post-treated as defined herein, and tested. After any stripping and recoating, parts shall meet the dimensional requirements of the drawing. 4.7.2If any p