1、)/-/-a4 MIL-B-BL794A 68 m 7777906 0322709 O MIL-B-81744A 31 August 1973 Superseding 27 October 1969 MIL-B-81744 (AS) MILITARY SPECIFICATION BARRIER COATING SOLUTION, LUBRICANT MIGRATION DETERRING This specification is approved for use by all Departments and Agencies of the Depart- ment of Defense. 1
2、. SCOPE 1.1 This specification covers the requirements for a lubri- cant-migration-deterring barrier coating solution consisting of a fluoro- polymer identified as poly (lH,lH-pentadecafluorooctyl methacrylate) dissolved in xylene hexafluoride. 2. APPLICABLE DOCUMENTS 2.1 The following documents of
3、the issue in effect on the date of invitation for bids or request for proposal form a part of this specification form a part of this specification to the extent specified herein. SPECIFICATIONS Federal QQ-S-76 3 Steel Bars, Shapes, and Forgings-Corrosion Res is t ing Military MIL-S-81087 Silicone Fl
4、uid, Chlorinated Phenyl Methyl Polysiloxane MIL-B-81744A/l Barrier Coating Solvent STANDARDS Federal Fed. Test Method Paint, Varnish, Lacquer; and Related Materials: Std. No. 141 Methods of Inspection, Sampling and Testing 1- FSC 6850 1 THiS DOCUMENT CONTAINS .z PAGES Provided by IHSNot for ResaleNo
5、 reproduction or networking permitted without license from IHS-,-,- MIL-B-81744A STANDARDS Military MIL-STD- Cont d) 29 Marking for Shipment and Storage Process for Barrier Coating of Anti-Friction MIL-STD-1334 Bearings (Copies of specifications and standards required by suppliers in con- nection wi
6、th procurement functions should be obtained from the procuring activity or as directed by the contracting officer.) 2.2 Other publications - The following documents form a part of this specification to the extent specified herein. Unless otherwise indicated, the issue in effect on the date of invita
7、tion for bids or re- quest for proposal shall apply. AMERICAN SOCIETY FOR TEST AND MATERIALS PUBLICATIONS ASTM Standards Parts 17 and 18 (Copies of ASTM Publications may be obtained from the American Society for Testing and Materials, 1916 Race Street, Philadelphia, Pennsylvania 19103. ) 3. REQUIREM
8、ENTS 3.1 Materi-als - The barrier coating solution shall be composed of a 2 per cent (by weight) solution of poly lH,lH-pentadecafluoraoctyl methacrylate in xylene hexafluoride (conforming to MIL-F-81744A/l to which has been added ultraviolet indicator Tenapol SSG (see 6.3) at a concentra- tion of 0
9、.2 per cent based on weight of the fluoropolymer. 3.2 Abrasion - A circle of barrier film prepared as specified in 4.2.3 and tested as specified in 4.2.4 shall, after being subjected to one abrasive stroke, prevent a drop of chlorinated silicone lubricant con- forming to MIL-S-81087 from passing acr
10、oss or through the film for 24 hours. 3.3 Contact angle - A drop of n-hexadecane shall form a contact angle of not less than 60 degrees when a film of the barrier coating is tested as specified in 4.2.5. 3.4 Thermal stability - A circle of barrier film when tested as specified in 4.2.6 at 3470F 53.6
11、F (175 +2“C) shall prevent the spread of a drop of the silicone from passing outside the barrier film for 24 hours. 3.5 Contamination in solution - When tested as specified in 4.2.7 a distilled water drop placed in the center of the circle of barrier film after the reagent grade acetone has evaporat
12、ed shall spread and not form a bead. 2 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-B-81744A 3.6 Indicator - When tested as specified in 4.2.8 the test surface shall fluoresce under black light. 3.7 is tested in accordance with 4.2.9, the nonv
13、olatile content shall be 2.0 - +0.1 grams. 3.8 Nonvolatile content - When the barrier coating solution Workmanship - The solution, when examined visually shall be clear, homogeneous, and free from suspended matter. 4. QUALITY ASSURANCE PROVISIONS 4.1 Responsibility for inspection - Unless otherwise
14、specified in the contract r purchase order, the supplier is responsible for the performance of all inspection requirements specified herein. Except as otherwise specified the supplier may use his own or any other facilities suitable for the performance of inspection requirements specified herein, un
15、less disapproved by the Government. The Government reserves the right to perform any of the inspections set forth in the specification where such inspections are deemed necessary to assure supplies and services conform to prescribed requirements. 4.2 Quality conformance inspection - 4.2.1 of a sampl
16、e for tests (4.2.1.3) and a sample for examination of filled con- tainers (4.2.1.4). Sampling - The quality conformance sample shall consist 4.2.1.1 - Lot - A lot of polymer (employed in the preparation of the solution) or solvent (employed in the preparation of solution) is de- fined as the yield f
17、rom a single series of chemical operations leading to production of the ingredients used to make the barrier coating solution. 4.2.1.2 Batch - A batch of the barrier coating solution is defined as the yield from a single series of operations, utilizing the same combi- nation of solvent and polymer.
18、constitute a new batch of solution. A change in either solvent or polymer shall 4.2.1.3 Samples for test - Before being placed in unit containers, two 10 ml samples from each batch of finished solution shall be taken. Each sample shall be identified by batch number, source of supply and date of manu
19、facture. The batch shall be unacceptable if a sample fails to meet any of the test requirements specified in Section 3. In addition, after filling and capping, each glass unit container (the same container in which the material is to be delivered) of solution shall be sampled, identified as above an
20、d tested for conformance with the test requirement of 4.2.7. material contained in the unit container shall be unacceptable if the sample fails to meet this test requirement. The 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-B-81744A 4.2.1.4
21、Sample for examination of filled containers - All filled shipping containers fully prepared for delivery from each batch shall be subjected to examination. 4.2.2 Inspection - Quality conformance inspection shall consist of an examination for acceptability of quality control methods used by the manuf
22、acturer, an examination of samples of filled containers (4.2.1.4) for conformance to packaging packing, and marking requirements, and examination and tests of samples (4.2.1.3) for all the requirements specified in Section 3. 4.2.3 Method for preparing film - Unless otherwise specified, the followin
23、g procedure shall be used to prepare films to be tested for conformance with the requirements of this specification. platen of stainless steel conforming to Class 302 or 304 of QQ-S-763 shall be abraded under running tap water with No. 600 waterproof silicon carbide paper and “Tide“ detergent (or eq
24、uivalent) until a random pattern has re- placed the oriented grinding marks. The platen shall then be flushed with distilled water to remove all traces of abrasive and detergent. (At this point it is important to verify that distilled water drains smoothly from the surface.) There shall be no area o
25、f test surface on which the water will draw up into droplets or pools, as if the surface were greasy. the distilled water flush the platen, while still wet with water shall be held vertically and flushed with reagent grade acetone to remove the re- maining water and cause rapid drying of the surface
26、. (Proof of the purity of the reagent grade acetone can be established after the acetone drying step by placing a sample platen in a horizontal plane and contacting it in the center with a large drop of distilled water, a hemispherical or dome shape the platen has an organic hydrophobic contami- nat
27、ing film present. will adversely affect the validity of test methods described below). Test rings of the barrier film shall be 0.5 to 0.75 inches outside diameter and the barrier band shall be about 0.1 inch wide. shall be applied with a small lintless tissue swab held with tweezers or with a small
28、piece of lintless tissue packed into the tip of a medicine dropper from the back side. The application should be made by only two circular passes with a damp (not dripping wet) swab. Care must be taken to avoid building a thick film, because thicker films are less adherent and are more easily dislod
29、ged. Satisfactory films should show a character- istic violet fluorescence when the film is illuminated by an ultraviolet light source described in 4.2.8. permit detection of holidays in the film which would prevent the barrier film from containing a lubricant. least 30 minutes before they are subje
30、cted to test. used for each of the tests specified herein. replicates pass a test, the sample shall be considered satisfactory for this test. A finish ground After If the drop maintains Such films probably result from impure acetone and The film forming solution Viewing under ultraviolet light will
31、Films shall be allowed to air dry at Three rings shall be If at least one of the three 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-B-81744A 4.2.4 Abrasion - Using circles of barrier film as prepared in 4.2.3, the tip of the index finger sha
32、ll be smoothly wrapped in fresh lens tissue, and placed firmly with a force of 2 to 3 pounds against the uncoated surface in the center of the ring and drawn, under the same pres- sure, against the barrier band onto the clean metal outside. The lens tissue from this ring shall not be used for anothe
33、r stroke or across another test ring, and only one stroke shall be made across each barrier film. After all test circles have been subjected to the abrasion stroke a small drop of MIL-S-81087 silicone shall be placed in the center of the test circles and the platens stood vertically with abraded sec
34、tions toward the bottom. The oil should flow downward to the margin of the barrier ring and be retained at this point. If, during a period of 24 hours, oil passes across or lifts the barrier, the barrier material shall be considered to have failed this test. 4.2.5 Contact angle - The contact angle f
35、ormed by a drop of n-hexadecane on the barrier film formed on a clean microscope slide by dipping it into the solution shall be read with a contact angle goniometer or by means of an eyepiece goniometer in a microscope fitted with low power (2X or 3x1 objective. The drop of n-hexadecane shall be for
36、med from the end of a clean 0.025 inch diameter nichrome wire. tus is not available the angle may be observed with sufficient accuracy either with an optical comparator or through the use of a Polaroid micro- graph showing the cross section outline and the plane on which it rests and using a protrac
37、tor to measure the angle through the liquid. If the above appara- 4.2.6 Thermal stability - Using circles of barrier films as prepared in 4.2.3.a drop of silicone conforming to MIL-S-81087 and formed from the end of a clean 0.025 inch diameter nichrome wire shall be placed in the center of separate
38、circles. dishes and stored horizontally in a convection oven controlled at 347 +3.6“F (175 +2OC) for 24 hours. is outside the barrier film circle. The samples shall be covered with petri Observations shall be made to see if any fluid 4.2.7 Contamination in solution - Each filled and capped unit cont
39、ainer of solution (see 4.2.1.3) shall be thoroughly shaken with cap in place. clean lintless swab. introduce contamination. Using the swab to apply circles of barrier film (as in 4.2.3) to acid cleaned glass.slides, a pool of reagent acetone shall be built up inside the circles using a medicine drop
40、per for initial insertion and for maintaining the pool against evaporation losses in 5 minutes. Then the acetone shall be permitted to evaporate to dryness, and a drop of distilled water added to center of the circle. Observation shall be made to determine if the water drop stands as a bead or wheth
41、er it spreads. The cap shall then be removed and a few drops poured out onto a The cap shall then be replaced, taking care not to 4.2.8 Ultraviolet fluorescent indicator - Using a clean micro- scope slide as prepared in 4.2.5 place under an ultraviolet lamp emitting 5 Provided by IHSNot for ResaleNo
42、 reproduction or networking permitted without license from IHS-,-,-MIL-B-81744A either 2537 Angstrom or 3660 Angstrom line in an otherwise unilluminated darkroom, in order to observe violet fluorescence. solution shall be determined in accordance with Method 4045 of Federal Test Method Standard 141.
43、 5. PREPARATION FOR DELIVERY 4.2.9 Nonvolatiles - The nonvolatiles of the barrier coating 5.1 Packaging - Unless otherwise specified packaging shall be Level A or C (see 6.2). 5.1.1 Level A - Unless otherwise specified the barrier coating Screwcaps shall be polyethylene or polypropylene, solution sh
44、all be packaged in wide mouthed clear glass bottles or epoxy- lined metal containers. with a layer of aluminum foil. 5.1.2 Level C - The barrier coating shall be packaged to afford the minimum degree of protection necessary to prevent damage during ship- ment under environmental conditions and comme
45、rcial modes of transportation. 5.2 Packing - Unless otherwise specified, packing shall be Level C (see 6.2). 5.2.1 Level C - Packages that require overpacking for accept- ance by the common carrier shall be packed in exterior type shipping con- tainers in a manner that will assure safe transportatio
46、n at the lowest cost to the point of delivery and shail meet as a minimum the requirements of the rules and regulations of the mode of transportation selected. 5.3 Marking - Marking shall be in accordance with MIL-STD-129. In addition to any special marking required by the contract or order, the uni
47、t containers shall be marked with the following information: Barrier Coating Solution, Lubricant Migration Deterring Specification MLL-B-81744A Contract No. Batch No. Lot No. Caution: This solution may interfere with any subsequent lubrication of surfaces with which it comes in contact. Particular c
48、are should be taken to avoid contamination of work areas and cleaning solutions. See MIL-STD-1334 for additional information. 6. NOTES 6 .i Intended use - The solution covered by this specification is furnished as a 2 percent solution of a fluoropolymer in xylene hexa- fluoride and is intended for a
49、pplication to selected surfaces of precision ball bearings to form thin oil-repellent film which retains the lubricant within the bearing and reduces lubricant migration. bearings is extended significantly and longer service lives of bearings The shelf life of Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-B-37LlLlA 68 = 9999906 0322735 6 MIL-B-81744A and bearing parts have been effected. The 2 percent concen
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