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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, Thin 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 ensure maximum paint adhesion, but usage is not limited to such applications. 1.2.1This process is applicable to all magnesium alloys provided proper
6、 allowance is made for dimensional change. It should not be used for parts flexed in service. Abrasion resistance is not as high as is provided with the alkaline electrolytic treatment of AMS 2476 or the full-coat, acid treatment of AMS 2478 but, when similarly painted or resin-coated, other propert
7、ies are equivalent. 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 address the hazards which may be involved in such use. It is the sole r
8、esponsibility 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 SPECIFICATION AMS 2479D Issued1966-09 Revised2003-01 Reaffirmed2007-11 Su
9、perseding AMS 2479C AMS 2479DSAEAMS 2479D - 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 document unless a specific d
10、ocument 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. AMS 2476Electrolytic Treatment
11、 for Magnesium Alloys, Alkaline Type, Full Coat AMS 2478Anodic Treatment of Magnesium Alloys, Acid Type, Full Coat AMS 4352Magnesium Alloy Extrusions, 5.5Zn - 0.45Zr (ZK60A-T5), Precipitation Heat-Treated 3.TECHNICAL REQUIREMENTS: 3.1Solutions: 3.1.1Electrolyte: Shall be an aqueous solution of one o
12、f the compositions shown in Table 1, maintained within the range 160 to 180 F (71 to 82 C). If neither alternating or direct current is specified, either may be used. TABLE 1A - Bath Composition, Inch/Pound Units Ingredient AC Process Quantity DC Process Quantity Ammonium Bifluoride, ounces (Avdp) p
13、er gallon (NH4FHF) Sodium Dichromate, ounces (Avdp) per gallon (Na2Cr2O72H2O) Phosphoric Acid, (fluid) ounces per gallon (85% H3PO4) 30 to 60.0 6.7 to 16.0 6.5 to 14.0 40.0 to 60.0 6.7 to 16.0 6.5 to 14.0 AMS 2479DSAEAMS 2479D - 3 - 3.1.2Sealer: Shall be an aqueous solution containing 6 to 8 ounces/
14、gallon (45 to 60 g/L) of sodium tetrasilicate (Na2Si4O9) maintained at a temperature within the range 200 to 212 F (93 to 100 C). 3.2Equipment: 3.2.1Tanks: Shall be fabricated from materials which are compatible with the solutions and temperature required for processing parts and shall be equipped w
15、ith facilities for maintaining the solutions within the operating temperature ranges specified. 3.2.2Fixtures: Wire, hooks, clamps, and racks used to suspend parts in the electrolyte and which are in contact with the electrolyte shall be of magnesium or magnesium alloys, or from (5000 or 6000 series
16、) aluminum alloys containing magnesium. Such fixtures shall be protected with a suitable maskant at the electrolyte-air interface. 3.3Preparation: 3.3.1Masking: Parts which contain inserts other than 5000 or 6000 series aluminum alloys and parts not to be anodized all over shall be masked to seal of
17、f 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 surfaces are free of water break. 3.3.3Racking, Attachment and Contact: Parts shall be firmly attached to the racks. Contact areas shall be
18、 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 located in areas indicated on the drawing. Parts shall, insofar as practicable, be hung to avoid gas entrapment during processing. 3.3.3.1AC Proce
19、ssing: Parts shall be distributed on both electrodes so that the surface areas of the parts on each electrode are approximately equal. TABLE 1B - Bath Composition, SI Units Ingredient AC Process Quantity DC Process Quantity Ammonium Bifluoride, grams/L (NH4FHF) Sodium Dichromate, grams/L (Na2Cr2O72H
20、2O) Phosphoric Acid, mL/L (85% H3PO4) 225 to 449 50 to 120 51 to 109 300 to 449 50 to 120 50 to 109 AMS 2479DSAEAMS 2479D - 4 - 3.3.3.2DC Processing: Parts shall be distributed on one electrode with the other electrode being separate steel plates except as noted in 3.4.1. 3.4Procedure: 3.4.1Processi
21、ng: The cleaned and racked parts shall be immersed in the electrolyte (See 8.3.1). 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. Alternating or direct current, as applicable, shall be applied and the volta
22、ge 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 shall be as shown in Table 2. 3.4.1.1Completion of processing is indicated by a uniform
23、, light green to gray 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, parts which will not be painted or which are to be partially painted shall be
24、 immersed in the sealer solution (3.1.2) for approximately 15 minutes immediately after coating. 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, and dried. 3.5Properties: Coatings shall
25、 conform to the following requirements: 3.5.1Coating Thickness: Shall be such that the dimensional increase will be 0.0001 to 0.0005 inch (2.5 to 12.7 m) per surface, determined by measuring before and after anodizing at the same locations, with a micrometer accurate to 0.0001 inch (2.5 m), dividing
26、 by two if opposite faces are anodized. Coating thickness may be determined by multiplying by 1.3. 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. Coa
27、ting weight shall be 0.400 to 2.000 grams/square foot (4.30 to 21.53 g/m2), determined as in 3.5.2.1. TABLE 2 - Power Input Type of CurrentTotal Power Input AC Process DC Process 80 to 100 ampere minutes/square foot (14.5 to 18.0 Asecond/m2) 50 to 60 ampere minutes/square foot ( 9.0 to 11.0 Asecond/
28、m2) -,-,- AMS 2479DSAEAMS 2479D - 5 - 3.5.2.1Weigh an oven-dried coated part or a coated test specimen as in 4.3.3. Strip the coating in a fresh, sulfate-free solution containing approximately 40 ounces/gallon (300 g/L) of chromic acid until the weight difference between successive weighings is less
29、 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 subtracting the weight of the stripped specimen from the weight prior to stripping and dividing by
30、the surface area. Oven drying temperature shall not be higher than 250 F (121 C). 3.6Quality: Surfaces of coated parts, as received by purchaser, shall be uniform in texture and appearance except that dark striations on parts made of extruded AMS 4352 magnesium alloy will be acceptable if pitting is
31、 not present. Powdery areas, laminations, excessive buildup, and darkening of corners and edges are not acceptable. There shall be no bare or definite light-colored areas except as approved by purchaser. 4.QUALITY ASSURANCE PROVISIONS: 4.1Responsibility for Inspection: The processor shall supply all
32、 samples for processors tests and shall be responsible for the performance of all required tests. Where parts are to be tested, such parts shall be supplied by purchaser. Purchaser reserves the right to sample and to perform any confirmatory testing deemed necessary to ensure that the coating confor
33、ms to the requirements of this specification. 4.2Classification of Tests: 4.2.1Acceptance Tests: Coating thickness (3.5.1) or coating weight (3.5.2), as applicable, and quality (3.6) are acceptance tests and shall be performed on each lot. 4.2.2Periodic Tests: Cleaning and processing solution tests
34、(See 8.5) to ensure that the deposited coating will conform to the requirements of this specification are periodic tests and shall be performed at a frequency selected by the processor unless frequency of testing is specified by purchaser. 4.2.3Preproduction Tests: All technical requirements are pre
35、production tests and shall be performed prior to or on the initial shipment of coated parts to a purchaser, when 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. AMS 2479DSAEA
36、MS 2479D - 6 - 4.3Sampling and Testing: 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 longer than eight consecutive hours, and presented for processors inspection at one time: 4.3.1For Accep
37、tance Tests: Shall be as shown in Table 3. 4.3.2For Periodic Tests: Sample quantity and frequency of testing shall be selected at the discretion of the processor, unless otherwise specified. 4.3.3Coating Thickness, and Coating Weight: Shall be determined on representative parts when size and shape p
38、ermit accurate determinations. If parts are of such size and shape that accurate determinations cannot be made, coating thickness, and coating weight tests shall be made on separate specimens, having surface area not less than 24 square inches (155 cm2), made of the same generic class of alloy as th
39、e parts represented. Separate specimens, if used, shall be processed with the work they represent. In case of dispute, results of tests on actual parts shall govern. 4.4Approval: 4.4.1The process and control factors, a preproduction sample, or both, whichever is specified by purchaser, shall be appr
40、oved 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 is approved by the cognizant engineering organization. A
41、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 Coating Thickness As Applicable Up to 7 8 to 15 16 to 40 41 t
42、o 110 111 to 300 301 to 500 Over 500 All 7 10 15 25 35 50 3 4 4 5 6 7 8 -,-,- AMS 2479DSAEAMS 2479D - 7 - 4.4.2.1Control factors for the process shall include, but not be limited to, the following: Cleaning procedure Racking set-up Composition limits for electrolyte Current and/or voltage control Fr
43、equency of solution(s) analysis Precleaning process 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 the acceptance test req
44、uirements. This report shall include the purchase order number, lot number, AMS 2479D, part number, type of current used, and quantity. 4.6Resampling and Retesting: 4.6.1If acceptance test fails to meet specified requirements, the parts in that lot may be stripped by a method acceptable to purchaser
45、 which does not roughen, pit, 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 may be stripped by a method a
46、cceptable to purchaser that does not roughen, pit, embrittle the basis metal, or adversely affect part dimensions, pretreated, recoated, post- treated as defined herein, and tested. After any stripping and recoating, parts shall meet the dimensional requirements of the drawing. 4.6.2If the results o
47、f any periodic test fail to meet the specified requirements, the process is nonconforming. No additional parts shall 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
48、 all parts coated since the last acceptable test. 5.PREPARATION FOR DELIVERY: 5.1Coated parts shall be handled and packaged to ensure that the required physical characteristics and properties of the coating are preserved. 5.2Packages of coated parts shall be prepared for shipment in accordance with
49、commercial practice and in compliance with applicable rules and regulations pertaining to the handling, packaging, and transportation of the coated parts to ensure carrier acceptance and safe delivery. 6.ACKNOWLEDGMENT: A processor shall mention this specification number and its revision letter in all quotations and when acknowledging purchase orders. AMS 2479DSAEAMS 2479D - 8 - 7.REJECTIONS: Parts on which the coating does not conform to this specification, or to modifications