1、AEROSPACE MATERIAL SPECIFICATION AMS03-18 Issued 2015-04 Chromate Conversion Coatings (Chromate Filming Treatments) Grades: Standard and Brushing for Aluminum and Aluminum Alloys RATIONALE This Standard is a direct replacement for DEF STAN 03-18 and has been reproduced by SAE International under the
2、 Open Government Licensing Agreement. The technical content remains unchanged from Issue 5 of the Defence Standard it supersedes. Any queries should be referred via the link shown in the feedback box at the bottom of this page. LICENSING AGREEMENT Ministry of Defence. Crown Copyright 2015. Reproduce
3、d under the terms of the Open Government License. FOREWORD REVISION NOTE This Defence Standard was raised to Issue 5 to update its content and incorporate the latest MoD/DStan policy in place at the time. HISTORICAL RECORD This standard supersedes the following: Def Stan 03-18 Issue 1 dated 28 Decem
4、ber 1979 Def Stan 03-18 Issue 2 dated 13 September 1997 Def Stan 03-18 Issue 3 dated 30 June 2003 Def Stan 03-18 Issue 4 dated 7 March 2008 _ 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
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7、n this Technical Report, please visit http:/www.sae.org/technical/standards/AMS03_18 SAE INTERNATIONAL AMS03-18 Page 2 of 12 INTRODUCTION Chromate conversion coatings give a measure of protection against corrosion, in particular under humid conditions. They can be used as paint bases because they ma
8、rkedly improve the adhesion and performance of paint schemes in Service environments. The process may also be used where the coating is required to be electrically conductive or for local repair of damaged anodic coatings where it may slightly degrade the abrasion resistance of the surrounding anodi
9、c film. The majority of chromate conversion coatings are applied by immersion or spraying techniques with provision for limited swab or brush application to small areas. There is, however, a requirement for a Brushing Grade of chromate conversion coating which can be applied by brush or swab to larg
10、e areas. Chromate conversion coatings have been used for over 50 years as treatment to coated or as-fabricated surfaces to boost corrosion resistance and provide a good basis for the subsequent application (where required) of paint. However such treatments are based on the use of hexavalent chromium
11、 chemicals which are extremely toxic. This has led to progressively greater restrictions, imposed by national and international legislation, related to concerns over health and safety and environmental protection, on the use of these treatments. Attention is drawn to Def Stan 03-38 which gives guida
12、nce on possible alternative processes. SAE INTERNATIONAL AMS03-18 Page 3 of 12 TABLE OF CONTENTS 1. SCOPE 4 2. WARNING . 4 3. NORMATIVE REFERENCES . 4 4. DEFINITIONS . 4 5. INFORMATION TO BE SUPPLIED TO THE PROCESSOR 5 6. PROCESS CONTROL 5 7. PREPARATION, COATING, AND SUPPLEMENTARY TREATMENTS 5 7.1
13、Preparation of Surface 5 7.1.1 Degreasing 5 7.1.2 General Cleaning 5 7.1.3 Cleaning Prior to Repair 6 7.2 Chromate Conversion Coating Treatments (see also Annex D) 6 7.2.1 Coating Types and Treatment 6 7.2.2 Washing and Drying after Treatment 6 7.3 Re-Treatment 7 8. PRODUCTION CONTROL AND INSPECTION
14、 7 8.1 Production Control 7 8.2 Inspection 7 9. NOTES 7 ANNEX A DETERMINATION OF THE MASS PER UNIT AREA OF CHROMATE CONVERSION COATINGS . 8 ANNEX B PROCESS CONTROL TESTS . 10 ANNEX C SPOT TEST FOR THE PRESENCE OF PROTECTIVE FILMS. 11 ANNEX D PROCESS SYSTEMS, FILM PROPERTIES 12 Table 1 Types and uses
15、 of chromate films 6 SAE INTERNATIONAL AMS03-18 Page 4 of 12 1. SCOPE 1.1 This SAE Standard specifies the properties of chromate conversion coatings on aluminum and aluminum alloys. It details inspection and testing requirements for chromate conversion coatings. 1.2 Where there are differences in th
16、e requirements for the Brushing Grade from the Standard Grade they are highlighted in this Standard. 2. WARNING This section which appeared in DEF STAN 03-18 Issue 5 has been deliberately deleted. 3. NORMATIVE REFERENCES 3.1 The publications shown below are referred to in the text of this standard.
17、Publications are grouped and listed in alpha-numeric order. ASTM B117 Standard practice for operating salt spray (fog) apparatus BS EN ISO 2409 Paints and Varnishes. Cross Cut Test BS EN ISO 9227 Corrosion Tests in Artificial Atmospheres. Salt Spray Tests BS EN 2089 Aluminium Alloy AL-P2014A-T6 or T
18、62. Sheet and Strip 0.4mm a 6mm BS EN 23270 Specification for Temperatures and Humidities for Conditioning and Testing Paints, Varnishes and their Raw Materials BS 2X 33 Specification for Two Component Epoxy Primer for Aerospace Purposes Def Stan 03-2 Cleaning and Preparation of Metal Surfaces AMS03
19、-2 Cleaning and Preparation of Metal Surfaces Def Stan 03-38 Guidance for the Use of Alternatives to Hexavalent Chromium for the Protective Coating of Defence Equipment Def Stan 80-161 Paint, Finishing, Spraying, Epoxy, Multi Pack 3.2 This section which appeared in DEF STAN 03-18 Issue 5 has been de
20、liberately deleted. 3.3 This section which appeared in DEF STAN 03-18 Issue 5 has been deliberately deleted. 3.4 This section which appeared in DEF STAN 03-18 Issue 5 has been deliberately deleted. 4. DEFINITIONS 4.1 For the purposes of this Part of the Standard the following definitions apply: 4.2
21、GRADES 4.2.1 Standard Grade This grade covers the normal immersion/spraying grade with limited application to small areas by brush or swabbing. SAE INTERNATIONAL AMS03-18 Page 5 of 12 4.2.2 Brushing Grade This grade covers products which are designed to be applied by brush or swab to large areas, i.
22、e., in excess of 1 square meter. The resultant chromate filmed surface is normally painted. 4.3 PROCESS CONTROL SCHEDULE The document which specifies/defines: a. The sequence of manufacturing operations and processes. b. The control parameters and their tolerances for each individual process within
23、the total sequence. 4.4 SIGNIFICANT SURFACE That area of the item, covered or to be covered by the coating, and for which the coating is essential for serviceability and/or appearance. 5. INFORMATION TO BE SUPPLIED TO THE PROCESSOR The following information shall be given on the drawing, contract or
24、 order: a. The number of this AMS Material Specification or its superseded Defence Standard. b. The grade of treatment (e.g., Standard Grade - see 4.2). c. The specification and metallurgical condition of the basis metal. d. The significant surface see 4.4. This may be indicated on the drawing or by
25、 a marked sample. e. The treatment method, see 7.2 et al. and type of coating required (see Table 1). f. The service use code, see Table 1. 6. PROCESS CONTROL 6.1 A Process Control Schedule suitable for achieving the requirements of this Standard shall be prepared by the processing contractor(s) pri
26、or to the commencement of production. 6.2 Details of the coating process, including all preparatory treatments, coating treatment and processing, significant surface, tests and all other treatments shall be included in the Process Control Schedule. 6.3 All stages in the complete Schedule shall follo
27、w each other without delay. 7. PREPARATION, COATING, AND SUPPLEMENTARY TREATMENTS 7.1 Preparation of Surface 7.1.1 Degreasing All surfaces shall be free from oil, grease and cleaning solution residue. 7.1.2 General Cleaning Items shall be cleaned and deoxidized in accordance with AMS03-2/Def Stan 03
28、-2. Casting skin on certain alloys may interfere with the subsequent production of satisfactory coatings. Casting skin may be removed by methods contained in AMS03-2/Def Stan 03-2. SAE INTERNATIONAL AMS03-18 Page 6 of 12 7.1.3 Cleaning Prior to Repair Only the affected area shall be cleaned as a min
29、imum. 7.2 Chromate Conversion Coating Treatments (see also Annex D) 7.2.1 Coating Types and Treatment 7.2.1.1 The chromate solutions covered in this Standard are based on hexavalent chromium chemistry. They are usually acidic and contain other components which may be varied to affect the appearance
30、and hardness of the film. The final coating will contain hexavalent and/or trivalent chromium salts. 7.2.1.2 The types of coating, related to service use, are shown in Table 1. 7.2.1.3 Items which are to be chromate coated can be immersed in static or agitated baths, sprayed, brushed or swab coated.
31、 Precise details of the working conditions will be found in the operating instructions for the various chromate filming treatments. 7.2.1.4 Different metallic materials should not be treated together in order to avoid galvanic corrosion. 7.2.1.5 Chromate conversion coatings harden with age by gradua
32、l dehydration and should therefore be handled carefully, and no tests undertaken, for the first 24 hours. Table 1 - Types and uses of chromate films Code Service Use Process Control Tests Recommended Color (but see D.2) Recommended coating mass per unit area, g/m2* C Corrosion resistance 8.1.1, 8.1.
33、3 Yellow-brown 0.4 - 2.0 E Electrical conductivity 8.1.1 Colorless-Iridescent 0.05 - 0.2 P Painting/bonding/priming 8.1.1, 8.1.2 Yellow 0.2 - 1.0 or as per drawing T Temporary protective surface (coating removed after storage) Light yellow * Coating mass may be determined by the method given in Anne
34、x A. 7.2.2 Washing and Drying after Treatment 7.2.2.1 After treatment, large structures shall be thoroughly washed using clean water (maximum temperature 50 C). 7.2.2.2 After treatment, other items shall be washed in clean running water (maximum temperature 50 C) to prevent over-treatment which will
35、 occur where the solution is retained. The normal time of washing is about 1 minute in order to minimize dissolution of the film constituents. It is recommended that items of irregular contour be washed in jets of water. All items shall then be finally rinsed in water having a conductivity not great
36、er than 20 mS/m (200 S/cm). A slight contamination by the processing solution is acceptable. 7.2.2.3 After washing and rinsing, items shall be dried as soon as possible in clean air at a temperature not exceeding 60 C. 7.2.2.4 The primer or first coat of the specified paint scheme shall be applied t
37、o the dry chromate filmed surface within 16 hours. SAE INTERNATIONAL AMS03-18 Page 7 of 12 7.3 Re-Treatment Unsatisfactory coatings shall be completely removed either mechanically, in accordance with AMS03-2/Def Stan 03-2, or chemically with the solution referenced in Annex A. Other chemical treatme
38、nts may be used, providing the properties of the subsequent conversion coatings and the basis metal are not adversely affected. After removal of unsatisfactory coatings, items shall be retreated in accordance with 7.1 and 7.2. 8. PRODUCTION CONTROL AND INSPECTION 8.1 Production Control 8.1.1 The pro
39、cess shall be carried out in accordance with the Process Control Schedule and shall comply with the requirements of Annex A. 8.1.2 For applications where chromate filmed surfaces are subsequently painted, tests for paint adhesion shall be carried out in accordance with Annex B, Test 1. 8.1.3 For app
40、lications where chromate filmed surfaces are not subsequently painted, tests for corrosion resistance (Code C only - see Table 1) shall be carried out in accordance with Annex B, Test 2. 8.1.4 Frequency of testing shall be such that the processor can demonstrate that the chromate film produced by th
41、e process meets the requirements of the appropriate test at Annex B. 8.2 Inspection 8.2.1 The chromate films shall be free of flaws or defects and shall not be powdery when examined with the unaided eye. The color of films resulting from the process may vary from colorless to golden yellow brown dep
42、ending on alloy composition and method of surface preparation. Iridescence and variations in color from one area to another will frequently be observed and are acceptable. Failure to color match within batch, batch to batch or where it has been necessary to process in more than one operation shall n
43、ot be cause for rejection. NOTE 1 Chromate conversion coatings are not intended as a color matching process. NOTE 2 Chromate films produced by the large scale brushing method (see 7.2.1.3) will result in greater variations in appearance than those obtained by the standard method. This is particularl
44、y apparent on surfaces which have been previously painted and stripped prior to re-chromate filming. 8.2.2 Dry films shall be adherent when tested 24 hours after processing with a white paper (or immediately prior to painting if this is less than 24 hours). The test shall consist of two strokes of w
45、hite paper such as a No. 40 Whatman filter paper under light finger pressure. No more than the faintest stain shall be shown on the paper and the film shall not show signs of having been removed. NOTE: For both performance and health and safety reasons, chromate films should not be handled with bare
46、 skin but with appropriately-chosen gloves. 8.2.3 The presence of a corrosion resistant film may be verified by applying the spot test described in Annex C. 9. NOTES 9.1 A change bar (l) located in the left margin is for the convenience of the user in locating areas where technical revisions, not ed
47、itorial changes, have been made to the previous issue of this document. 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 chan
48、ges only. UNDER THE JURISDICTION OF AMS COMMITTEE “B“ SAE INTERNATIONAL AMS03-18 Page 8 of 12 ANNEX A - DETERMINATION OF THE MASS PER UNIT AREA OF CHROMATE CONVERSION COATINGS A.1 METHODOLOGY A.1.1 The coating weight may be determined using a strip and weigh technique. The coated sample is weighed a
49、nd then reweighed after removal of the coating by immersion in a bath containing one of the reagents given in Table A1. A.1.1.1 Both the reagents in Table A1 attack the basis material to a slight degree. The loss of mass per unit area after 10 minutes pickling is in the order of 0.1 g/m2. If necessary, this loss must be determined separately and be taken into account in determining the weight per unit area. Table A1 - Reagents for dete
