NOT MEASUREMENT
SENSITIVE
MIL-DTL-13924D
18 March 1999
SUPERSEDING
MIL-C-13924C
9 June l980
DETAIL SPECIFICATION
COATING, OXIDE, BLACK, FOR FERROUS METALS
This specification is approved for u by all Departments
and Agencies of the Department of Defen.
1. SCOPE
1.1 Scope. This specification covers black oxide coatings applied to ferrous
metals (wrought iron, carbon, low alloy, and corrosion resistant steels). Black
oxide coatings, with or without a supplementary prervative treatment (e 3.11),
may be ud where a black surface is required. Only very limited corrosion
protection, under mildly corrosive conditions, is obtained as a result of black
oxide coating (e 6.1). Black coatings are included in this specification with limitations as noted in 1.2.
1.2 Classification. Black oxide coatings covered by this specification should be
of the following class as specified (e 6.2 and 6.3.2).
Class 1Alkaline oxidizing process (for wrought iron, cast and malleable
irons, plain carbon, and low alloy steels).
Class 2Alkaline chromate oxidizing process (for u on certain corrosion resistant steel alloys which are tempered at less than 900°F (482°C)).
Class 3Fud salt oxidizing process (for corrosion resistant steel alloys which are tempered at 900°F (482°C) or higher).
Class 4Alkaline oxidizing process (for other corrosion resistant steel
alloys).
Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of u in improving this document should be addresd to: Director,
U.S. Army Rearch Laboratory, Weapons and Materials Rearch Directorate,
ATTN: AMSRL-WM-M, Aberdeen Proving Ground, MD 21005-5069 by using the
Standardization Document Improvement Proposal (DD Form 1426) appearing at the end
of this document or by letter.
AMSC N/A AREA MFFP
2. APPLICABLE DOCUMENTS
2.1 General. The documents listed in this ction are specified in ctions 3
工作单位英文and 4 of this specification. This ction does not include documents in other
ctions of this specification or recommended for additional information or as
examples. While every effort has been made to ensure the completeness of this list, document urs are cautioned that they must meet all specified requirements
documents cited in ctions 3 and 4 of this specification, whether or not they are listed.
2.2 Government documents.
2.2.1 Specifications, standards, and handbooks. The following specifications, standards, and handbooks form a part of this document to the extent specified
herein. Unless otherwi specified, the issues of the documents are tho listed
in the issue of the Department of Defen Index of Specifications and
Standards(DoDISS) and supplement thereto, cited in the solicitation (e 6.2). SPECIFICATIONS
DEPARTMENT OF DEFENSE
MIL-C-53072 Chemical Agent Resistant Coating (CARC) System Application
Procedures And Quality Control Inspection
(Unless otherwi indicated, copies of the above specifications, standards, and handbooks are available from the Defen Automated Printing Service (DAPS), Building 4D, 700 Robbins Avenue, Philadelphia, PA 19111-5094).
2.3 Non-Government publications. The following documents form a part of this document to the extent specified herein. Unless otherwi specified, the issues of
the documents which are DoD adopted are tho listed in the issue of the DoDISS cited
in the solicitation. Unless otherwi specified, the issues of documents not listed
in the DoDISS are the issues of the documents cited in the solicitation (e 6.2). AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM)
ASTM B117 Operating Salt Spray (Fog) Apparatus (DoD adopted)
ASTM F519 Mechanical Hydrogen Embrittlement Testing of Plating Process
and Aircraft Maintenance Chemicals
(Application for copies should be addresd to the American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959.)
SOCIETY OF AUTOMOTIVE ENGINEERS, INC. (SAE)
AMS 2759/9 Hydrogen Embrittlement Relief (Baking) Of Steel Parts
(Application for copies should be addresd to the Society Of Automotive
Engineers, Inc., 400 Commonwealth Drive, Warrendale, PA 15096.)
2.4 Order of precedence. In the event of a conflict between the text of this document and the refere
nces cited herein, the text of this document takes
precedence. Nothing in this document, however, superdes applicable laws and
regulations unless a specific exemption has been obtained.深信不疑的意思
3. REQUIREMENTS
3.1 Materials. The materials for the blackening process shall be lected by就业推荐表怎么填
the contractor. The lected materials shall result in black coatings meeting all
the applicable requirements of this specification.
3.2 Preparation of basis metal. Prior to the application of the black coatings,
the basis metal shall be thoroughly cleaned. The cleaned surfaces shall be free of rust, scale, grea, oil, paint, or other foreign matter, and shall pass the water break test described in MIL-C-53072. Cleaning materials and methods shall be at the option of the contractor. The cleaning process shall be performed without
measurable abrasion or erosion.
3.2.1 Stress relief. Unless otherwi specified for a particular end item specification or drawing, after forming and hardening, and prior to cleaning and coating, objectionable residual stress in ferrous alloy parts having a hardness
greater than 40 HRC shall be relieved by suitable heat treatment. The temperature shall be such that maximum relief is given without hardness being reduced to less
than the specified minimum. Stress relief is not necessary where it has been demonstrated that coating has no harmful effect on the coated part.
3.2.2 Coating as a final process. Unless otherwi specified, the black coatings shall be applied after all machining, forming, welding, cold straightening and heat treatment have been completed.
3.3 Application of black coatings. The coating shall conform to the class specified. The specified black coating shall be applied under controlled time and temperature conditions. All equipment together with solutions or baths shall be properly maintained and kept free of dirt or possible contaminants. The lected process shall not reduce the hardness of the parts being procesd or expo the
parts to temperatures in the temper brittle range of the material, nor shall it
cau embrittlement of the steel.
3.3.1 Surface attack. The process shall not result in any attack of the surface, either pitting or intergranular.
3.4 Alkaline oxidizing solutions (class 1 and 2). Class 1 and 2 oxide coatings shall be formed from a boiling alkaline oxidizing or alkaline chromate oxidizing solution, respectively.
3.4.1 Rinsing. All class of black oxide coated pieces shall be rind in cold water.
3.4.2 Chromic acid dip. After the cold water rin (e 3.4.1) the pieces shall面相痣的图片大全
be dipped for a minimum of 30 conds in a 0.06 percent solution (8 oz. chromic acid per 100 gallons water) of chromic acid maintained at a temperature of l50 to l90°F
(66 to 88°C) and a pH of 2 to 3. After the chromic acid dip, parts shall be dried without further rinsing by using warm dry air.
3.5 Fud salt oxidizing (class 3). The temperature of the molten oxidizing salt
of class 3 shall not be higher than 900°F (482°C). After suitable immersion, the treated parts shall be withdrawn, cooled from eight to ten minutes and rind in hot water, l90°F (88°C), followed by thorough cold water rinsing to effect complete
removal of blackening solution. After rinsing, the parts shall be dried by warm dry air and given a chromic acid dip as outlined in 3.4.2.
3.6 Alkaline oxidizing (class 4). The black coating of class 4 shall be
procesd in accordance with instructions furnished by the suppliers of the raw materials and the resulting coating shall conform to the applicable requirements of this specification.
3.7 Coverage and color. Class 1, 2, 3, and 4 coatings (e 1.2) shall cover the basis metal completely and shall pass the smut test. The color shall be a uniform black. A slight amount of smut, which is inherent in the process, shall not be cau for rejection. There shall be no indication of any reddish-brown or green smut when tested as in
4.4.1. Smut "spottiness" shall be classified as
通辽信息港招聘unsatisfactory requiring reprocessing.
3.8 Oxalic acid spot test (class 1, 2, and 3). The black oxide coatings of class 1, 2, and 3, prior to the application of a prervative, shall pass the oxalic acid spot test for a good quality coating (figure 3) as specified in
4.4.2.
3.9 Resistance to salt spray (fog) (class 4 AISI type 300 ries corrosion resistant steel only). The black coating, of class 4 (300 ries only), prior to学习与思考
the application of a prervative, shall show no signs of corrosion after 96 hours
of exposure in the salt spray test (e 4.4.3).
3.10 Hydrogen embrittlement relief treatment. Steel parts that are surface or through hardened at 40 HRC and above shall be given a hydrogen embrittlement relief treatment after application of the oxide coating. Coated springs or other parts subject to flexure shall not be flexed prior to the embrittlement relief treatment. If an embrittlement relief treatment is required, it shall follow the chromic acid rin. The embrittlement relief treatment precedes the supplementary prervative treatment.
3.11 Supplementary prervative. Materials for supplementary prervative treatments and methods of application shall be in accordance with the applicable requirements of the end item specification, or as otherwi specified. Unless otherwi specified, the supplementary prervative treatment shall be applied to
the clean and dry parts immediately after the final stage of processing.
3.12 Workmanship. The surface of the coated part shall be uniform in appearance and free of visible coating defects, such as blisters, pits, roughness, nodules, burning, cracks, or uncoated areas, and other defects that will affect the function of the coating. The coated parts shall be clean and free of damage.
4. VERIFICATION
4.1 Responsibility for inspection. Unless otherwi specified in the contract or purcha order, the contractor is responsible for the performance of all inspection requirements (examinations and tests) as specified herein. Except as otherwi specified in the contract or purcha order, the contractor may u his own or any other facilities suitable for the performance of the inspection requirements
specified herein, unless disapproved by the Government. The Government rerves the right to perform any of the inspections t forth in this specification where such inspections are deemed necessary to ensure supplies and rvices conform to
prescribed requirements.
4.1.1 Classification. All the tests required for the testing are classified as quality conformance tests, for which necessary sampling techniques and the methods
of testing are specified in this ction.
4.2 Sampling.
4.2.1 Lot. A lot shall consist of coated parts of the same class, same basis metal, and approximately the same size and shape and coated under similar
conditions. A maximum of 8 hours continuous production shall constitute a lot.
4.2.2 Selection. The number of random samples lected for nondestructive tests (visual inspection, coverage, color, smut, and workmanship), and destructive tests (oxalic acid spot test, salt spray test, and embrittlement relief test) from each
lot of coated parts shall be defined by the procuring activity (e 6.2).
4.3 Acceptance and rejection. The lected coated parts shall meet the
requirements in this specification for the reprented lot to be acceptable.
Failure of any test samples to meet the requirements in this specification shall constitute rejection of the entire lot which they reprent. Unless otherwi
specified (e 6.2), the tests shall be conducted and the test results accepted
prior to shipment of the lot of coated parts reprented by the test samples.
4.3.1 Surface attack. Parts shall be examined for pitted surfaces or
intergranular attack by viewing them at magnifications up to 10x.
高数学习4.4 Test procedures.
4.4.1 Smut test. The test shall be made prior to application of corrosion
preventive compound or after vapor degreasing. Each black oxide coated piece shall be inspected visually under strong light to assure a satisfactory appearance. Each sample shall also be wiped with a clean white cloth for indications of smut (e 3.7).
A slight amount of smut which is inherent in the process is acceptable for all class of coatings and shall not be cau for rejection.
4.4.2 Oxalic acid spot test (class 1, 2, and 3). The black oxide coated pieces of class 1, 2, and 3 only, prior to the application of a prervative, shall be handled with clean cotton gloves or the equivalent. Each sample shall have deposited, on one flat spot of the black oxide coated surface, three drops (0.00676 oz. (0.2 ml)) of a five percent solution of oxalic acid. The reaction shall be obrved after 30 conds and up to eight minutes. After eight minutes the panel shall be rind and compared
to figures 1, 2, and 3. A light gray center with a lighter border color (figure 1) indicates a poor quality coating. A gray-black center with a light border (figure 2) indicates a borderline quality coating. The coating shall conform to the good quality coating of figure 3 to be acceptable. A black or dark brown center with a light
border (figure 3) indicates a good quality coating. A good quality coating may show a light border, indicating exposure of metal around the drops. Parts shall therefore be judged only on the color and exposure of the metal under the drops.
4.4.3 Resistance to salt spray (class 4). The coated pieces of class 4
(AISI type 300 ries corrosion resistant steel) shall be subjected to a 5 percent
capturesalt spray (fog) test in accordance with ASTM B117. Exposure time for the black coatings, prior to the application of a prervative, or after vapor degreasing,
shall comply with the requirements of 3.9.
