1、 MIL-DTL-32459 26 JUNE 2013 DETAIL SPECIFICATION COATINGS, ANODIC FOR MAGNESIUM AND MAGNESIUM ALLOYS This specification is approved for use by all Departments and Agencies of the Department of Defense 1. SCOPE 1.1 Scope. This specification covers the general requirements for the application and insp
2、ection of applying an anodic, hexavalent chromium-free and HAP (Hazardous Air Pollutants) free coating to magnesium alloys parts, newly developed and/or used parts that have been stripped and cleaned down to the base metal (magnesium alloy). These coatings will provide corrosion protection and abras
3、ive resistance properties to magnesium base metals, including magnesium alloys and to produce a surface suitable for the subsequent application of a protective organic finish (see 6.1), as applicable. 1.2 Classification. The types and classes of anodic coatings and of anodizing solutions that are co
4、vered by this specification are as follows (see 6.2). 1.2.1 Types. Anodic finishes are classified by coating thicknesses (see Table I for a summary). Type I. Type I finishes are considered thin and have a coating thickness in the range of 0.0002 to 0.0004 inch (5 to 10 m) when applied by immersion.
5、Type II. Type II finishes are considered heavy or intermediate and have a coating thickness in the range of 0.0005 to 0.0007 inch (13 to 18 m) when applied by immersion. Type III. Type III finishes are considered thick and have a coating thickness in the range of 0.0008 to 0.0010 inch (20 to 25 m) w
6、hen applied by immersion. Comments, suggestions, or questions on this document should be addressed to: Director, U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Specifications and Standards Office, Attn: RDRL-WMM-D, Aberdeen Proving Ground, MD 21005-5069 or emailed to rich
7、ard.j.squillacioti.civmail.mil. Since contact information can change, you may want to verify the currency of this address information using the ASSIST Online database at https:/assist.dla.mil/. AMSC N/A AREA MFFP DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. INCH-
8、POUND Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-32459 2 Type IV. Type IV finishes have a coating thickness in the range of 0.0001 to 0.0003 inch (2.5 to 7.5 m) when applied by brushing with a high voltage. Type V. Type V finishes have a
9、 coating thickness that is less than 0.0002 inch (5 m) when applied by brushing with a low voltage. TABLE I. Characteristics of the various types of anodic coatings. COATING TYPE DESCRIPTION THICKNESS RANGE APPLICATION Type I Immersion Thin 0.0002 to 0.0004 inch Immersion Type II Immersion Heavy or
10、Intermediate 0.0005 to 0.0007 inch Immersion Type III Immersion Thick 0.0008 to 0.0010 inch Immersion Type IV Thick Touchup 0.0001 to 0.0003 inch High voltage Brushing Type V Thin Touchup less than 0.0002 inch Low voltage Brushing 1.2.2 Classes. Anodizing classifications (see Table II for a summary)
11、. Class A. Use Class A anodizing solution for parts made from magnesium alloys not listed in Class B or Class C. Class B. Use Class B anodizing solution for parts made of EV31 and WE43 magnesium alloys. Class C. Use Class C anodizing solution for parts made of QE22 magnesium alloys. Class D. Use Cla
12、ss D anodizing solution for Type V finishes. TABLE II. Characteristics of the various anodizing classes. CLASS ANODIZING SOLUTION TO BE USED ON PARTS MADE FROM Class A Magnesium alloys not listed in Class B or Class C Class B EV31 and WE43 magnesium alloys Class C QE22 magnesium alloys Class D Type
13、V finishes 1.2.3 Engineering drawing default. When the anodic coating type is not specified on the engineering drawing or in another specification, Type I should be used. The anodizing solution class should be as specified in 1.2.2. There is no requirement to specify the solution class on the engine
14、ering drawing. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-32459 3 1.3 Safety-Hazardous Materials. Hazardous materials should be handled in accordance with all Federal, State, and local regulations. 2. APPLICABLE DOCUMENTS 2.1 General. Th
15、e documents listed in this section are specified in sections 3, 4, or 5 of this specification. This section does not include documents cited in other sections of this specification or recommended for additional information or as examples. While every effort has been made to ensure the completeness o
16、f this list, document users are cautioned that they must meet all specified requirements of documents cited in sections 3, 4, or 5 of this specification, whether or not they are listed. 2.2 Government documents. 2.2.1 Specifications, standards, and handbooks. The following specifications, standards,
17、 and handbooks form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract. FEDERAL SPECIFICATIONS A-A-58054 - Abrasive Mats, Non-Woven, Non-Metallic DEPARTMENT OF DEFENSE SPECIFICATIONS MIL-PR
18、F-23377 - Primer Coatings: Epoxy, High-Solids MIL-PRF-85582 - Primer Coatings: Epoxy, Waterborne (Copies of these documents are available online at http:/quicksearch.dla.mil or https:/assist.dla.mil or from the Standardization Document Order Desk, 700 Robbins Avenue, Building 4D, Philadelphia, PA 19
19、111-5094.) 2.3 Non-Government publications. The following documents form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract. ASTM INTERNATIONAL ASTM B117 - Standard Practice for Operating S
20、alt Spray (Fog) Apparatus ASTM B244 - Standard Test Method for Measurement of Thickness of Anodic Coatings on Aluminum and of Other Nonconductive Coatings on Nonmagnetic Basis Metals with Eddy-Current Instruments Provided by IHSNot for ResaleNo reproduction or networking permitted without license fr
21、om IHS-,-,-MIL-DTL-32459 4 ASTM D610 - Standard Practice for Evaluating Degree of Rusting on Painted Steel Surfaces ASTM D1193 - Standard Specification for Reagent Water ASTM D1654 - Standard Test Method for Evaluation of Painted or Coated Specimens Subjected to Corrosive Environments ASTM D3359 - S
22、tandard Test Methods for Measuring Adhesion by Tape Test ASTM D4060 - Standard Test Method for Abrasion Resistance of Organic Coatings by the Taber Abraser ASTM E466 - Standard Practice for Conducting Force Controlled Constant Amplitude Axial Fatigue Tests of Metallic Materials (Copies of these docu
23、ments are available online from www.astm.org or ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959.) 2.4 Order of precedence. Unless otherwise noted herein or in the contract, in the event of a conflict between the text of this document and the references cited
24、herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 3. REQUIREMENTS 3.1 First article. When specified (see 6.2), a sample shall be subjected to first article inspection in acc
25、ordance with 4.4. 3.2 Materials. The materials used shall be such as to produce coatings which meet the requirements of this specification. 3.2.1 Abrasive mats. Abrasive mats shall be non-woven, non-metallic mats made of nylon fiber conforming to A-A-58054 Type I, Grade A (Type I, Aluminum oxide (mi
26、nimum of 94 % AL/ 0/3 and a hardness of 9.4 Mohs); Grade A, Grit size 280 to 400 or finer (ScotchBrite or equivalent). 3.2.2 Alkaline etch cleaner. The alkaline cleaner to be used shall contain 50 70 g/L of borate and 30 50 g/L of pyrophosphate. 3.2.3 Pretreatment solution. The pretreatment solution
27、 shall be as specified in the contract or purchase order (see 6.2). It shall contain 40 70 g/L of fluorides. The pretreatment solution is also knows as Fluoride Activator solution. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-32459 5 3.2.4
28、 Anodizing solutions. Class A, B and C anodizing solutions shall be alkaline, chromate-free, and contain silicates. Class B anodizing solutions shall also contain vanadate. Class A, B and C anodizing solutions shall contain 1 12 g/L of silicate and Class B anodizing solutions shall contain 0.3 1.2 g
29、/L of vanadate. Class D anodizing solutions shall contain 2.5 16.5 g/L of silicate. Solutions used for anodizing shall be capable of producing coatings that conform to all requirements specified herein. All anodizing solutions shall not contain any HAPs or carcinogens and have no adverse effects on
30、human health when used as intended. 3.2.5 Reverse osmosis (RO) water. RO water must be Type III or better as defined in the conductivity specification in ASTM D1193. 3.2.6 Masking. All liners, bushings, inserts, dissimilar metal and other hardware shall be removed from parts or shall be masked prior
31、 to anodizing to prevent solution contact during processing. 3.2.6.1 Masking materials. Masking materials shall be either organic or inorganic materials that are suitable to seal off dissimilar metals and other hardware on the magnesium component. Masking materials must be chemical compatible with p
32、retreatment and anodizing processes. 3.2.7 Panels. Panels utilized herein shall be made from the following magnesium alloys: AZ91, EV31, QE22, WE43, ZE41 and other magnesium alloys that have been approved by the contract or purchase order (See 6.2). The specific alloy specification shall be specifie
33、d in the contract or purchase order (see 6.2). 3.2.8 Post treatment solution. Unless otherwise specified in the contract or purchase order (see 6.2), the post treatment solution shall contain 128 166 g/L of sodium di-hydrogen phosphate (NaH2PO4). If post treatment is not specified only water rinses
34、will be done. 3.2.9 Primer, epoxy. The epoxy primer shall be made in accordance with Type I, Class N of MIL-PRF-23377, or Type I, Class N of MIL-PRF-85582. 3.3 Parts. 3.3.1 Used parts. All parts that have been in service or previously coated or anodized shall be stripped and/or clean down to the bas
35、e magnesium alloy and shall now be considered equivalent to new parts and all of its requirements shall be met (see 6.6). 3.3.2 New parts. All new parts shall have clean surfaces, free from water break, prior to immersion in the anodizing solution and be free from broken edges before anodizing and u
36、nless otherwise specified in the contract or purchase order (see 6.2), shall have all machining, drilling or other metal removal done prior to anodizing. All parts shall be subjected to cleaning, etching, anodizing and sealing procedures as necessary to yield coatings meeting all the requirements of
37、 this specification. 3.4 Equipment and processes. The following equipment is required to perform the procedures and operations described in this specification. Unless otherwise specified in the contract or purchase order (see 6.2), process operating conditions shall be at the option of the supplier.
38、 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-32459 6 3.4.1 Anodizing unit - Brush. The brush anodizing unit shall consist of rectifiers, cables, clamps, collection trays, carts, and fixtures of such type as to produce Type IV and Type V c
39、oatings which conform to the requirements specified herein (see 1.2.1.4 and 1.2.1.5). 3.4.2. Continuity tester or resistance tester, low-voltage. An ohmmeter or multimeter with a 9 V battery source capable of measuring 1M or greater shall be utilized. 3.4.3 Electrical items. Electrical items shall c
40、onsist of rectifiers, bus bars, cathodes, recorders, and controls suitable to meet requirements specified in Table III. Meters on electrical items shall be accurate to 1 percent of range. TABLE III. Coating requirements. Coating Type Coating Thickness Approximate Dimensional Buildup (No Etch) Approx
41、imate Dimensional Buildup (with 3 minute etch time) Approximate Dimensional Buildup (with 5 - 10 minute etch time) Type I 0.0002 to 0.0004 inch 0.0001 to 0.0002 inch 0.0000 to 0.0001 inch -0.0001 to 0.0001 inch Type II 0.0005 to 0.0007 inch 0.00025 to 0.00035 inch 0.00015 to 0.00025 inch -0.0001 to
42、0.00015 inch Type III 0.0008 to 0.0010 inch 0.0004 to 0.0005 inch 0.0003 to 0.0004 inch 0.0002 to 0.0003 inch Type IV 0.0001 to 0.0003 inch 0.00005 to 0.00015 inch N/A N/A Type V Less than 0.0002 inch N/A N/A N/A 3.4.4 Fixtures. Fixtures shall consist of a set of suitable hardware that can be used t
43、o suspend parts in the anodizing solution in the immersion tanks, shall be of materials that are fully compatible with the anodizing process. 3.4.5 Safety equipment. Safety equipment includes plastic or rubber aprons, boots, chemical goggles, face masks and gloves. 3.4.6 Tanks. Tanks used for immers
44、ion baths shall be fabricated from or coated with compatible materials. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-32459 7 3.4.6.1 Controls. Tanks shall be equipped with environment controls allowing agitation of immersion bath solution
45、and controlling temperature variations within the specified limits. 3.4.6.2 Ventilation. The ventilation of immersion tanks shall be provided as required by Federal, State, local or company regulations. 3.5 Environmental, health and safety. Equipment, materials, solutions, and emissions (if applicab
46、le) shall be controlled, handled, used, and disposed of in accordance with all local Federal and State regulations. 3.6 Procedures and operations. 3.6.1 Preparation. 3.6.1.1 Fabrication. All operations that are part of a components fabrication shall be completed before the component is anodized. All
47、 detachable hardware shall be removed or un-detachable dissimilar metals shall be masked from the component before anodization (Type I, II, or III). The masked components shall be touchup anodized (Type IV or V) after the immersion. 3.6.1.2 Electrical contacts. Electrical contacts between the compon
48、ent being anodized and the power source shall be firmly connected to avoid uninterrupted current flow and thereby eliminating local overheating of the component. Electrical contact location shall be applied in an area where the anodization is not required or is optional. Components shall be suspende
49、d such that gas entrapment during anodization is minimized. 3.6.1.3 Blind holes. Prior to immersion or being anodized, blind holes may be plugged with the appropriate material, such as, silicon, polypropylene, or nylon plugs. Material used shall be chemical compatible with a high pH, caustic environment. Plugged holes shall be subsequently brush anodized (Typ
