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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 Anodic Treatment of Magnesium Alloys Acid Type, Full Coat 1.SCOPE: 1.1Purpose: This specification establishes the engineering requirements for producing an acid-type, anodic coating on magnesium alloys and the properties
5、 of the coating. 1.2Application: This process 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. 1.2.1This process is applicable to all magnesium alloys provided proper allowa
6、nce is made for dimensional change. It should not be used on parts which will be flexed in service. Abrasion resistance is not as high as that provided with the alkaline electrolytic treatment of AMS 2476 but, when similarly painted or coated, other properties are equivalent. AMS 2478 coatings often
7、 exhibit poor adhesion to surfaces of castings. Thin coatings in accordance with AMS 2479 are preferred for castings. 1.3Safety - Hazardous Materials: While the materials, methods, applications, and processes described or referenced in this specification may involve the use of hazardous materials, t
8、his 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 precautionary measures to ensure the health and safety of all personnel invo
9、lved. AEROSPACE MATERIAL SPECIFICATION AMS 2478E Issued1957-09 Revised2003-01 Reaffirmed2007-11 Superseding AMS 2478D Copyright SAE International Provided by IHS under license with SAELicensee=MHI - NAGOYA related to 3944000/3944000013 Not for Resale, 01/23/2008 22:16:38 MSTNo reproduction or networ
10、king permitted without license from IHS -,-,- AMS 2478ESAEAMS 2478E - 2 - 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 a do
11、cument 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. 2.1SAE Publications: Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001 or ww
12、w.sae.org. AMS 2476Electrolytic Treatment for Magnesium Alloys, Alkaline Type, Full Coat AMS 2479Anodic Treatment of Magnesium Alloys, Acid Type, Thin Coat AMS 4352Magnesium Alloy Extrusions, 5.5Zn - 0.45Zr (ZK60A-T5), Precipitation Heat-Treated 2.2ASTM Publications: Available from ASTM, 100 Barr Ha
13、rbor Drive, West Conshohocken, PA 19428-2959 or www.astm.org. ASTM B 244Measurement of Thickness of Anodic Coatings on Aluminum and Other Nonconductive Coatings on Nonmagnetic Basis Metals with Eddy- Current Instruments ASTM B 487Measurement of Metal and Oxide Coating Thicknesses by Microscopical Ex
14、amination of a Cross Section 3.TECHNICAL REQUIREMENTS: 3.1Solutions: 3.1.1Electrolyte: Shall be an aqueous solution of one of the compositions shown in Table 1, maintained within the temperature range 175 to 185 F (79 to 85 C). If the type of current is not specified, either alternating current (AC)
15、 or direct current (DC) may be used. Alternative processing solutions may be used if acceptable to purchaser. TABLE 1A - Bath Composition, Inch/Pound Units Ingredient AC Process Quantity DC Process Quantity Ammonium Bifluoride, ounces (Avdp) per gallon (NH4FHF)30.0 to 60.040.0 to 60.0 Sodium Dichrom
16、ate, ounces (Avdp) per gallon (Na2Cr2O72H2O) 6.7 to 16.0 6.7 to 16.0 Phosphoric Acid, fluid ounces per gallon (85% H3PO4) 6.5 to 14.0 6.5 to 14.0 Copyright SAE International Provided by IHS under license with SAELicensee=MHI - NAGOYA related to 3944000/3944000013 Not for Resale, 01/23/2008 22:16:38
17、MSTNo reproduction or networking permitted without license from IHS -,-,- AMS 2478ESAEAMS 2478E - 3 - 3.1.2Sealer: Shall be an aqueous solution containing 6 to 8 ounces/gallon (45 to 60 grams/L) of sodium tetrasilicate (Na2Si4O9) maintained at a temperature of 200 o 212 F (93 to 100 C). 3.2Equipment
18、: 3.2.1Tanks: Shall be fabricated from a material or lined with a coating that is compatible with the anodizing bath and shall be equipped with temperature controls capable of controlling the bath temperature within specified limits. 3.2.2Fixtures: Wire, hooks, clamps, and racks used to suspend part
19、s in the electrolyte and which are in contact with the electrolyte shall be of magnesium or magnesium alloys, or from aluminum alloys containing magnesium (5000 or 6000 series). Such fixtures shall be protected with a suitable maskant at the electrolyte-air interface. 3.3Preparation: 3.3.1Masking: P
20、arts which contain inserts other than 5000 or 6000 series aluminum alloys and parts not to be anodized all over shall be masked to seal off the non-magnesium or non-aluminum materials and the surfaces not to be anodized. 3.3.2Cleaning: Parts shall be pickled and cleaned as necessary to ensure that s
21、urfaces are free from water break. 3.3.3Racking: 3.3.3.1AC Processing: Parts shall be distributed on both electrodes so that the surface areas of the parts on each electrode are approximately equal. 3.3.3.2DC Processing: Parts shall be distributed on one electrode with the other electrode being sepa
22、rate steel plates except as noted in 3.4.1. 3.3.3.3Attachment and Contact: Parts shall be firmly attached to the racks. Contact areas shall be kept as small as possible and, when practicable, shall be on surfaces not required to be coated. When parts are to be coated all over, contacts shall be loca
23、ted in areas indicated on the drawing. Parts shall, insofar as practicable, be hung to avoid gas entrapment during processing. TABLE 1B - Bath Composition, SI Units Ingredient AC Process Quantity DC Process Quantity Ammonium Bifluoride, grams/L (NH4FHF)225 to 449300 to 449 Sodium Dichromate, grams/L
24、 (Na2Cr2O72H2O) 50 to 120 50 to 120 Phosphoric Acid, mL/L (85% H3PO4) 51 to 109 51 to 109 Copyright SAE International Provided by IHS under license with SAELicensee=MHI - NAGOYA related to 3944000/3944000013 Not for Resale, 01/23/2008 22:16:38 MSTNo reproduction or networking permitted without licen
25、se from IHS -,-,- AMS 2478ESAEAMS 2478E - 4 - 3.4Procedure: 3.4.1Processing: The cleaned and racked parts shall be immersed in the electrolyte (See 8.4.1). The parts shall be made the anode in the DC process and, for this process, the tank may serve as the cathode if it is made of unlined steel. Alt
26、ernating or direct current, as applicable, shall be applied and the voltage raised manually or automatically during processing to maintain the required current density. Current density shall be maintained so that, in a processing time of not more than 30 minutes, the total power input will be not le
27、ss than that shown in Table 2. 3.4.1.1Completion of processing is indicated by a uniform, dark green color, free from definite bare or light colored areas except as permitted in 3.6, examined, while wet, after rinsing in cold water. 3.4.2Sealing: When specified, immediately after coating and rinsing
28、, parts not to be painted or which are to be only partly painted shall be immersed in the sealer solution for approximately 15 minutes. 3.4.3Rinsing and Drying: After anodizing, or after sealing when specified, parts shall be rinsed thoroughly in cold, running tap water, rinsed in clean, hot water,
29、and dried. 3.5Properties: The coating shall conform to the following requirements: 3.5.1Coating Thickness: Coating shall result in a dimensional increase of 0.0009 to 0.0016 inch (23 to 40 m) per surface, determined on representative parts or specimens (4.3.3) in accordance with ASTM B 244, ASTM B 4
30、87, by direct micrometer measurements, or by other method acceptable to purchaser. 3.5.2Coating Weight: If the size or shape of parts is such that coating thickness cannot be determined accurately, determination of coating weight may be substituted for determination of thickness. Coating weight shal
31、l be 3.600 to 6.400 grams/square foot (38.75 to 68.89 g/m2), determined as in 3.5.2.1. 3.5.2.1Weigh an oven dried coated part or a coated test specimen (4.3.3). Strip the coating in a fresh, sulfate-free solution containing approximately 40 ounces/gallon (300 g/L) of chromic acid. Repeat the immersi
32、on in the stripping solution until the weight difference between successive weighings is less than 1.0 milligram/square inch (0.155 mg/cm2). After each stripping operation, wash the part or test specimen with distilled water and oven dry thoroughly before weighing. Determine coating weight by subtra
33、cting the weight of the stripped specimen from the weight prior to stripping and dividing by the surface area. TABLE 2 - Power Input Type of CurrentTotal Power Input AC Process DC Process 460 ampere minutes/square foot (85 Asecond/m2) 300 ampere minutes/square foot (55 Asecond/m2) Copyright SAE Inte
34、rnational Provided by IHS under license with SAELicensee=MHI - NAGOYA related to 3944000/3944000013 Not for Resale, 01/23/2008 22:16:38 MSTNo reproduction or networking permitted without license from IHS -,-,- AMS 2478ESAEAMS 2478E - 5 - 3.6Quality: Surfaces of coated parts, as received by purchaser
35、, shall be uniform in texture and appearance except that dark striations on parts made of extruded AMS 4352 magnesium alloy will be acceptable if no pitting is present. Powdery areas, laminations, excessive buildup, and darkening of corners and edges are not acceptable. There shall be no bare or def
36、inite light-colored areas except as approved by purchaser. 4.QUALITY ASSURANCE PROVISIONS: 4.1Responsibility for Inspection: The processor shall supply all specimens for processors tests and shall be responsible for the performance of all required tests. Where parts are to be tested, such parts shal
37、l be supplied by purchaser. Purchaser reserves the right to sample and to perform any confirmatory testing deemed necessary to ensure that the coating conforms to the requirements of this specification. 4.2Classification of Tests: 4.2.1Acceptance Tests: Coating thickness (3.5.1) or coating weight (3
38、.5.2), as applicable, and quality (3.5) are acceptance tests and shall be performed on each lot. 4.2.2Periodic Tests: Cleaning and processing solution tests (See 8.6) to ensure that the anodic coating will conform to specified requirements are periodic tests and shall be performed at a frequency sel
39、ected by the processor 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 processed parts to a purchaser, when a change in material and/ or processing requir
40、es approval by the cognizant engineering organization (See 4.4.2), and when purchaser deems confirmatory testing to be required. 4.3Sampling: Shall be not less than the following; a lot shall be all parts of the same basis material, processed in the same solutions under the same conditions in not lo
41、nger than eight consecutive hours, and presented for processors inspection at one time: Copyright SAE International Provided by IHS under license with SAELicensee=MHI - NAGOYA related to 3944000/3944000013 Not for Resale, 01/23/2008 22:16:38 MSTNo reproduction or networking permitted without license
42、 from IHS -,-,- AMS 2478ESAEAMS 2478E - 6 - 4.3.1For Acceptance Tests: Shall be 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. 4.3.3Coating Thickness and Coating Weight: Shall be determined
43、 on representative parts when size and shape permit accurate determinations. If parts are of such size and shape that accurate determination cannot readily be made, coating thickness and coating weight tests shall be made on separate specimens, having surface area not less than 24 square inches (155
44、 cm2), made of the same generic class of alloy as the parts represented. Separate specimens, if used, shall be processed with the parts they represent. In case of dispute, results of tests on actual parts shall govern. 4.4Approval: 4.4.1The process and control procedures, a preproduction sample, or
45、both, whichever is specified by purchaser, shall be approved by the cognizant engineering organization before production parts are supplied. 4.4.2The processor shall make no significant change to materials, processes, or control factors from those on which the approval was based, unless the change i
46、s approved by the cognizant engineering organization. A significant change is one which, in the judgment of the cognizant engineering organization, could affect the properties or performance of the parts. TABLE 3 - Sampling for Acceptance Testing Number of Parts in LotQuality Coating Weight or Coati
47、ng Thickness As Applicable Up to 7 8 to 15 16 to 40 41 to 110 111 to 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 22:16:38 MSTNo reproduction
48、 or networking permitted without license from IHS -,-,- AMS 2478ESAEAMS 2478E - 7 - 4.4.2.1Control factors for the process shall include, but not be limited to, the following: Cleaning procedure Composition limits for electrolyte Electrolyte operating temperature and limits Racking setup Coating cur
49、rent density Current density limits Sealer composition limits Thickess determination method Periodic test plan 4.5Reports: The processor of coated parts shall furnish with each shipment a report stating that the parts have been processed and tested in accordance with specified requirements and that they conform to