1、 MIL-STD-871B (USAF) METRIC01March 2007 SUPERSEDING MIL-STD-871A 24 May 1979 DEPARTMENT OF DEFENSE STANDARD PRACTICE ELECTRO-CHEMICAL STRIPPING OF INORGANIC FINISHES This document is inactive for new design. AMSC: N/A AREA: MFP Provided by IHSNot for ResaleNo reproduction or networking permitted wit
2、hout license from IHS-,-,-MIL-STD-871B FOREWORD 1. This Military Standard is approved for use by 309MXSG/MXR, Department of the Air Force, and is available for use by all departments and agencies of the Department of Defense. 2. This standard provides guidance for the repair process, acquisition, an
3、d manufacture of parts and/or spare parts on the landing gear of all military aircraft. 3. Beneficial comments, recommendations, additions, deletions, clarifications, etc. and any data that may improve this document should be sent to: 309MXSG/MXRIL, Hill AFB, UT 84056-2609 or e-mailed to: 309MXSG/MX
4、RLhill.af.mil. Since contact information can change, verification of currency of this address information through ASSIST Online database at http:/assist.daps.dla.mil. ii Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-871B CONTENTS PARAGRAPHS
5、 PAGE FOREWORD i 1. SCOPE 1 1.1 Scope 2. APPLICABLE DOCUMENTS 1 2.1 General 2.2 Government Documents 1 2.2.1 Specifications, standards, handbooks, and commercial item descriptions 1 2.2.2 Other Government documents 2 2.3 Non-Government Publications 2 2.4 Order of Precedence 2 3. DEFINITIONS 3 3.1 Hi
6、gh Strength Steel 3 4. GENERAL REQUIREMENTS 3 4.1 Materials and Equipment 3 4.1.1 Materials 3 4.1.2 Equipment 4 4.2 Finish 4 4.3 Racking 4 4.4 Masking 4 4.5 Baking 4 4.5.1 Special Baking Requirement 4 5. DETAILED REQUIREMENTS 4 5.1 Immersion of Parts 4 5.2 Dissimilar Metals 4 5.3 Immersion Processes
7、 4 5.4 Baking 5 5.5 Procedure 5.6 Stripping Solutions 8 5.6.1 Solution 1: Cyanide Caustic 9 5.6.2 Solution 2: Nitric Acid 8 5.6.3 Solution 3: Ammonium Nitrate 8 iii Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-871B CONTENTS PARAGRAPHS PAGE
8、5.6.4 Solution 4: Hydrochloric Acid 9 5.6.5 Solution 5: Hydroxide Carbonate 9 5.6.6 Solution 6: Sodium Hydroxide 9 5.6.7 Solution 7: Sulfuric Acid 9 5.6.8 Solution 8: Acetic Acid 10 5.6.9 Solution 9: Sulfuric Nitric Acid 5.6.10 Solution 10: Chromic Acid 10 5.6.11 Solution 11: Cyanide Caustic 5.6.12
9、Solution 12: Chromic Phosphoric Acid 1 5.6.13 Solution 13: Chromic Sulfuric Acid 5.6.14 Solution 14: Multi-deposit Strip 12 5.6.15 Solution 15: Chrome Strip from Aluminum 5.7 Solution Makeup 12 5.8 Analysis 3 5.9 Rejection of Parts 1 6. NOTES 13 6.1 Intended Use 13 6.2 13 6.3 CONCLUDING MATERIALS 13
10、 iv Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-871B 1. SCOPE 1.1 Scope. This standard covers the process and materials required for the stripping of inorganic finishes. Subsequent heat treating techniques needed to insure hydrogen embrit
11、tlement relief of the steel substrate are also described. 2. APPLICABLE DOCUMENTS 2.1 General. The documents listed in this section are specified in Sections 4 and 5 of this standard. This section does not include documents cited in other sections of this standard or recommended for additional infor
12、mation or as examples. While every effort has been made to ensure the completeness of this list, document users are cautioned that they must meet all specified requirements of documents cited in Section 4 and 5 of this standard, whether or not they are listed. 2.2 Government Documents.2.2.1 Specific
13、ations, standards, handbooks, and commercial item descriptions. The following specifications, standards, handbooks, and commercial item descriptions form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitat
14、ion or contract. COMMERCIAL ITEM DESCRIPTIONS A-A-55820 Ortho-phosphoric (Phosphoric) Acid, Technical A-A-55827 Chromium Trioxide, Technical A-A-55828 Sulfuric Acid, Technical A-A-55829 Acetic Acid, Glacial, Technical A-A-59105 Nitric Acid, Technical A-A-59282 Chemicals, Analytical A-A-59476 Ammoniu
15、m Nitrate, Technical A-A-59563 Sodium, Carbonate, Anhydrous, Technical DEPARTMENT OF DEFENSE SPECIFICATIONS MIL-C-5541 Chemical Conversion Coatings on Aluminum and Aluminum Alloys (Copies of these documents are available from the Standardization Document Order Desk, 700 Robbins Avenue, Building 4D,
16、Philadelphia, PA 19111-5094, or http:/assist.daps.dla.mil.online/start/.) 1 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-871B 2.2.2 Other Government documents. The following Government document form a part of this document to the extent sp
17、ecified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract. CODE OF FEDERAL REGULATIONS (CFR) 29 CFR 1910 Toxic and Hazardous Substances (Copies of this document are available online at www.access.gpo.gov/nara.cfr or from the Superintend
18、ent of Documents, U.S. Printing Office, North Capitol & “H” Streets, N.W., Washington, D.C. 20402-0002.) 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 t
19、he solicitation or contract. AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM) ASTM E1146 Standard Specification for Muriatic Acid ASTM D1732 Standard Specification for Preparagraphtion of Magnesium Alloy Surfaces for Painting (Copies of these documents are available from www.astm.org or ASTM Intern
20、ational 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959.) SOCIETY OF AUTOMOTIVE ENGINEERS (SAE) INTERNATIONL SAE-AMS-M-3171 Magnesium Alloy, Processes for Pre-treatment And Prevention of Corrosion (Copies of these documents are available from www.sae.org or SAE World Headquart
21、ers, 400 Commonwealth Drive, Warrensdale, PA 15096-0001.) AMERICAN CHEMICAL SOCIETY (ACS) “Reagent Chemicals” (for replacement of Federal Specification O-G-491D). (Copies of these documents are available from American Chemical Society, 1155 16thStreet, N.W. Washington, D.C. 20036.) 2.4 Order of prec
22、edence. In the event of a conflict between the text of this document and the references cited 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. 2 Provided by IHSNot for Resa
23、leNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-871B 3. DEFINITIONS 3.1 High Strength Steel. For the purpose of this standard, high strength steel is defined as steel heat treated to 1240 mega-pascals (MPa) (126 kilogram force per millimeter square Kgf/mm2 180,000 poun
24、d force per square inch PSI) and above. 4. GENERAL REQUIREMENTS 4.1 Materials and Equipment. Materials and equipment used in electro/chemical stripping of inorganic finishes are as follows: 4.1.1 Materials. The use of re-claimed materials shall be encouraged to the maximum extent as possible. (CAUTI
25、ON: Some of these materials are classified as hazardous and toxic substances. Personnel exposure to such materials must be within the limits specified in OSHA Standard 1900-1000.) a. Acetic Acid, Glacial (A-A-55829) b. Ammonium Nitrate (A-A-59476) c. Antimony Trioxide, Technical Grade d. Chromic Aci
26、d (A-A-55827) e. Glycerin (ACS Standard) f. Hydrochloric Acid (ASTM E1146) g. Hydrogen Peroxide h. Nitric Acid (A-A-59105) i. Phosphoric Acid (A-A-55820) j. Sodium Carbonate (A-A-59563) k. Sodium Cyanide, Plating Grade l. Sodium Hydroxide m. Sulfuric Acid (A-A-55828) 3 Provided by IHSNot for ResaleN
27、o reproduction or networking permitted without license from IHS-,-,-MIL-STD-871B 4.1.2 Equipment. a. Tanks should be resistant to the operating temperatures and the chemical environment. b. Stripping tanks to be operated at temperatures other than room temperatures shall be equipped with automatic t
28、emperature indicating and regulating devices. c. Either generated or rectified D.C. current may be used. An ammeter shall be placed in series with the tank anode. The ammeter shall have sufficient shunts and switches to provide a full-scale reading equal to the maximum capacity of the power source,
29、and an accuracy of 10 percent of the current being measured. d. An oven capable of baking parts at 190 14C (375 25F) shall be located near the stripping line. The size of the oven shall be adequate to enclose the parts to be stripped. The oven shall be equipped with temperature indicating, recording
30、, and regulating devices. 4.2 Finish. The part, after stripping shall have a finish that is smooth and free from pits, nodules, and any other indications of harmful defects. 4.3 Racking. Sufficient contact area and pressure shall be provided to carry the current without overheating. Racking should b
31、e performed at the most convenient step prior to stripping. 4.4 Masking. Sections or areas of a part that are not to be stripped shall be masked off. Plug and masking materials that do not contaminate the stripping solution shall be used. Masking shall be performed at the most convenient step prior
32、to stripping. 4.5 Baking. All requirements for baking of the part shall be met. 4.5.1 Special baking requirement. Steel parts heat treated to 1240 MPa (180,000 psi) and above, shall be baked within four (4) hours of stripping for four (4) hours minimum at 190 14C (375 25F). Other process operations
33、can be performed on the part provided they are accomplished within the time limit. No plating process may be used prior to baking. NOTE: Steel parts stripped in solutions 1, 3, 5, 6, 11, and 14 will not require baking. 5. DETAILED REQUIREMENTS 5.1 Immersion of Parts. Parts shall be immersed in the p
34、rocess solution in a manner to prevent localized effects such as interface attack. 5.2 Dissimilar Metals. Dissimilar metal inserts shall be masked off or removed as necessary. 5.3 Immersion Processes. Immersion processes for stripping are preferred for parts having recessed areas, intricate shapes,
35、or hollow areas. 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-871B 5.4 Baking. Parts shall be baked for stress relief for four (4) hours minimum at 191 14C (376 25F) prior to stripping. 5.5 Procedure.a. Step No. 1. Degrease parts prior t
36、o further processing. Emulsion cleaning methods may be used if materials and equipment are available. b. Step No. 2. Mask and rack parts as necessary. c. Step No. 3. Strip inorganic coating in the appropriate solutions from Table I or II. Strip parts in the shortest time necessary to remove coating.
37、 Refer to Table III for information on solution makeup, control limits and process notes. d. Step No. 4. Rinse part immediately in clean water. e. Step No. 5. Rinse the part in hot water to facilitate drying. f. Step No. 6. Bake steel parts heat treated above 1240 MPa (180,000 psi) in accordance wit
38、h paragraph. 4.5. g. Step No. 7. Inspect as necessary for the requirements of paragraphs 4 and 5. TABLE I Stripping of Metal CoatingsCoating/ Base Metal Low Alloy Steel Corrosion Resistant Steel Aluminum Alloys Copper Alloys Brass Or Bronze 1 or 14 1, 2, 14 2 or 14 1N/A Cadmium Or Titanium cadmium 1
39、 or 3 1, 2, 3 2 3 or 4 5 or 6 5 or 6 7 or 15 4 Chromium 1, 2, 14 2 or 14 N/A Copper 1 or 14 2, 6, 8, 14 2 or 14 8 or 14 Lead or Lead Solder 6, 82, 14 Gold 1 1 7 1 12, 7, 14 2, 14 7, 14 Nickel or Electroless Nickel 72, 14 Silver 1 1 or 2 2 1 1or 9 Tin 1, 4 26, 14 1, 2, 4, 6, 14 2 or 14 4 or 14 Zinc 1
40、 or 42 1, 2, 4 2 4 5 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-871B 1CAUTION: This solution attacks the bare metal. 2CAUTION: This solution cannot be used for steels heat treated to 1241 MPa (180 kip/in2ksi). TABLE II Stripping of Conve
41、rsion Coatings _ BASE METAL COATING STRIPPING SOLUTION Ferrous Black Oxide 4 Ferrous Manganese Phosphate 10 or 11 Ferrous Zinc Phosphate 10 or 11 Ferrous Ferrous Phosphate 10 or 11 Ferrous Dry Film Lubricants 10 Magnesium ASTM D1732 10 Magnesium SAE-AMS-M-3171 10 Aluminum Dry Film Lubricants 10 Alum
42、inum MIL-C-5541 12 Aluminum Anodized Coatings 12 or 13 Zinc Conversion Coatings 12 Cadmium Conversion Coatings 12 6 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-871B TABLE III Process Solutions _ Stripping Solution Section Processing Solut
43、ion Immersion Electrolytic 1 5.6.1 Cyanide Caustic x 2 5.6.2 Nitric Acid x 3 5.6.3 Ammonium Nitrate x 4 5.6.4 Hydrochloric Acid x 5 5.6.5 Hydroxide Carbonate x 6 5.6.6 Sodium Hydroxide x 7 5.6.7 Sulfuric Acid x 8 5.6.8 Acetic Acid-Hydrogen x Peroxide 9 5.6.9 Sulfuric Nitric Acid x 10 5.6.10 Chromic
44、Acid x 11 5.6.11 Caustic Cyanide x 12 5.6.12 Chromic Phosphoric Acid x 13 5.6.13 Chromic Sulfuric x 14 5.6.14 Multi-deposit Strip x 15 5.6.15 Chrome Strip from Aluminum x The above stripping solutions are referenced in the Table I and II. Refer to the listed sections for information on solution make
45、-up, control limits, and process notes. Proprietary formulations are available for several of these processes. One example is a non-cyanide formulation to replace the cyanide based Multi-Deposit Strip, Solution 14. Proprietary formulations may be used provided the necessary precautions are taken to
46、avoid substrate attack and hydrogen embrittlement. If a proprietary formulation is used, testing must be accomplished to determine whether an embrittlement relief bake is required (Reference 4.5.1). 7 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-871B 5.6. Stripping Solutions. 5.6.1 Solutio
