1、I MIL-P-27418(USAF) 14 July 1967 MILITARY SPECIFICATION PLATING, SOFT NICKEL (ELECTRODEPOSITED, SULFANATE BATH) t 1. SCOPE 1.1 Scope, This specification covers the processes and requirements for soft nickel plating. 2. APPLICABLE IxKwENTs Not applicable 3. REQUIREMENTS 3.1 Materials. The materials u
2、red shall be such as to produce .coatings which meet the requirements of this specification. 3,2 Workmanship . 3.2.1 Basis metal. The basis metal shall be free from visible defects that will be detrimental to the performance of the plating, Articles to be plated shall be stress relieved, cleaned, et
3、ched, pickled, plated, and annealed as required to produce plating as specified herein, 3.2,2 Platinq. The nickel plating shall be smooth, columnar crystal- line (before annealing - 6,3), adherent, and free from visible blisters, pits, nodules, porosity, indications of burning and excessive edge bui
4、ldup, and other defects. Slight discoloration resulting from annealing, shall not be cause for rejection. All details of workmanship shall conform to the best practice for high-quality plating. 3.3 General requirements . 3.3.1 Unless otherwise specified, the plating shall be applied after all basis-
5、metal heat treatments and mechanical operations such as machining, brazing, welding, forming, and perforating on the article have been completed. 3.3.2 All articles shall be given a suitable stress-relief heat treat- ment prior to cleaning and plating. The temperature shall be such that I maximum st
6、ress relief is obtained without reduction in hardness to less than L the specified minimum. i i i Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-3.3.3 Unless otherwise specified, the plating shall be electrodeposited in an all-sulfamate, chloride-fr
7、ee nickel bath (6.3). 3.3.4 All articles shall be annealed in a vacuum furnace after plating to obtain the proper plating hardness. 3.4 Detail requirements. 3.4.1 Plating thickness. Unless otherwise specified, the plating shall be 0,002Q inch f 0.0003 inch thick on all surfaces to be plated which ca
8、n be touched by a ball 1/16 inch in diameter. 3.4.2 Plating boundaries. Unless otherwise specified, boundaries of the plating which covers only a portion of the surface shall be free from beads, nodiles, jagged edges, and other irregularities, and shall blend smoothly into the unplated surface. 3.4.
9、3 Plating hardness. Unless otherwise specified, the Knoop hard- ness of the plating after annealing shall not exceed 150 with a 500-gram load 3.4.4 Plating adnesion. Whzn examined at a magnification of approxi- mately 4 diameters, adhesion of the nickel plating shall not show separation from the bas
10、is metal when subjected to the test specified in 4.4.2. The fornation of cracks in the basis metal which do not result in flaking, peeling, or blistering of the coating shall not be considered as nonconfor- mance to this requirementr 3.4.5 Process deviations. Deviations from the specified plating an
11、d annealing requirements of this specification may be authorized by the Govemnent inspector or the procuring activity provided the contractor demonstrates that coatings thus produced are equivalent (6.3), for the pcrpose intended, to coatings produced under the specified conditions. Doubtful cases s
12、hall be referred to the procuring activity for decision, 4.1 Responsibilitv for inspection. Unless otherwise specified by the contract or purchase order, the supplier is responsible for the performance of all inspection requirements as specified herein. Except as otherwise specified, the supplier ma
13、y utilize his own facilities or any COmetCial laboratory accepta3le to th0 Government, The Government reserves the right to perfom any of the inspections set forth in the specification where such inspections are deemed necessary to assure supplies and services conform to prescribed requirements . “
14、- 2 P Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4.2 Separate specimens. When the plated articles are of such form as to be not readily adaptable to a test specified herein, or at the discretion of the inspector for destructive tests for the sam
15、pling of small lot sizes, or as otherwise specified herein, the test shall be made by the use of spearate specimens plated and annealed concurrently with the articles repre- sented. The separate specimens shall be of a basis metal equivalent to that of the articles represented. “Equivalent“ basis me
16、tal includes chemical composition, heat treatment, and finish of surface prior to plating. Due to the impracticability of forging separate test specimens, equivalent hot- rolled steel specimens may be used to represent forged steel articles. The separate specimens shall be strips approximately 1 inc
17、h wide, 4 inches long, and 0.04 inch thick, These specimens shall be introduced into a lot prior to the cleaning operations preliminary to plating and annealing processes. Conditions affecting the plating and annealing of the specimens including the spacing and positioning with respect to anodes and
18、 to other objects being plated, and with respect to the heating surfaces, shall correspond as nearly as possible to those affecting the significant surfaces of the articles represented. 4.3 SamplinR. 4.3.1 S. A lot shall consist of plated articles of approximately the am size and shape, plated and a
19、nnealed concurrently and submitted for inspection at one time. Lot size shall not exceed 500 articles, 4.3.1.1 Inspection records of the examination and tests shall be kept complete and available to the Government as specified in the contract or order. 4.3.2 Samplin procedures for visual examination
20、, A sample shall be taken from each lot by taking at random from the lot the number of articles indicated in table T. The lot shall be accepted or rejected on the basis of the sample according to the procedures in 4.3.2.1. TABLE I Sampling for visual inspection Number -of articles in lot 15 or less
21、16 to 40 41 to 110 111 to 300 301 to 500 Number of articles in sample (randomly selected) - 1/ 7 10 15 25 35 Acceptance number (maximum number of sample articles nonconforming to any test) O O O 1 1 I I I I I I/ If the number of articles in the lot is less than 7, tle numberw or articles in the samp
22、le shall equal the number of articles in the lot, i. - , “ . 3 I . J Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-483,281 Visual inspection. The number of sample articles indicated in table I shall be taken at random from the lot to be inspected a
23、nd ex- amined visually and compared with requirements of 3.2.7. after annealing. If the number of nonconforming articles in any sample exceeds the accept- ance number for that sample, the lot represented by the sample shall be rejected. 4.3.3 Sanpling procedure for hardness, adhesion. and coating th
24、ickness tests. A small, random sample of articles shall be selected from each lot by the Government inspector and three separate specimens shall be prepared in accordance with 4.2 to represent each lot. The number of articles in the sample shall be determined by the procuring activity or shall be le
25、ft to the discretion of the inspector. Each randomly selected sample article shall be subjected to the thickness test and each of the three separate specimens shall be subjected to the hardness, adhesion, and thickness tests. 4,383.1 Hardness. Each specimen shall be tested in accordance with 4.481 i
26、n several locations at which the plating hardness would be expected to be maximum. If the hardness at any place on any specimen is greater than the specified hardness, the lot shall be rejected. 4.383.2 Adhesion. Each specimen shall be tested in accordance with 4.4.2. Failure of one or more of the t
27、est specimens shall constitute failure of the lot . 4.3.3.3 Thickness (destructive test), Each article and specimen shall be tested in accordance with 4,4.3 in several locations at which the plating thickness would be expected to be minimum. If the plating thickness at any place not affected by the
28、hardness or adhesion tests is greater than or less than the specified thickness limits, the lot shall be rejected, 4.4 Test methods. 4.4.1 Hardness. Standard hardness testing procedures shall be used to determine the hoop hardness of the coating within? 5 percent of its true hardness. 4.4.2 Adhesion
29、, The test specimens shall be bent repeatedly through an angle of 180 degrees on a diameter equal to the thickness of the speci- men until fracture of the basis metal occurs. Following fracture of the basis metal, it shall not be possible to detach any appreciable areas of the coating with a sharp i
30、nstrument . 4.4.3 Thickness. Standard metallographic procedures shall be used to determine the coating thickness with a microscope, The specific method and equipment used shall be such that the coating thickness shall be deter- mined within 2 10 percent of its true thickness. 4 “-“- “-. - Provided b
31、y IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4.5 Replating. Unless otherwise specified, plated articles which have been rejected or withdrawn because of the presence of plating de- fects may be resubmitted after stripping, replating, and reannealing the ent
32、ire lot. Complete details of the replating and reannealing shall be furnished to, and be approved by, the inspector or procuring activity. 5. PREPARATION FOR DELIVERY 5.1 There are no general packaging, packing, or marking requirements applicable to this specification. Packaging when required shall
33、be as specified by the procuring activity. 6. NOTES 6.1 Intended use. The plating conforming to this specification is intended to facilitate the formation of a seal between two metallic sur- f aces . 6.2 Ordering data. Requisitions, contracts, and orders should be accompanied by drawings of the arti
34、cles to be plated. The procurement documents should specify the following: (a) Title, number, and date of this specification. (b) Instructions concerning the areas to be plated, deviations from the specified plating thickness, and any other necessary information pertinent to the plated surfaces. (c)
35、 Instructions concerning the number of articles to be selected for the thickness test (4.3.3). (d) Instructions concerning samples for approval (6.6) . 6.3 Plating; type. According to considerable laboratory testing, the nickel plating best suited to creating a seal when yielded against a metallic s
36、urface has a columnar crystalline structure before annealing. This structure is illustrated in figure 1. When a process other than the one specified is recommended by the contractor, the resulting structure of the plating before annealing should closely approximate the structure shown in figure 1. 6
37、.4 Plating; hardness. The acceptance of the plating is determined according to this specification by tests made after annealing. However, when the Knoop hardness of the plating prior to annealing is less than 300 with a 500-gram load, the eventual acceptability of the plating after annealing is indi
38、cated (3.4.3). 5 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Nickel plating Basis metal Figure 1. Columnar crystalldne strvcture of soft niskel plating prior to annealing, (5QQX) 6.5 e The dimensional tolerances of most seals do not allow s in pl
39、ating thickness. The plating thickness covered by this specification (0,0020 inch) has been selected to provide maximum uniformity and minimum shear stresses during deformation. When other thicknesses BKB desired, adequate testa must be made to determine the performance of the desired thickness, 6 -
40、6 o This specification describes the characteristics necessary to secure the desired plating. Unless othemfse specified, no samples will be necessary pris%. to award to determine compliance With this spesification. Ifp OK any particular purpose, samples with bids are necessary, they should be specif
41、ically asked for in the ivi- eation OK bids, and the particular purpose to be served by the bid sample should be definitely stated, the specification to apply to all other respects e Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-CU$ todians : Air F
42、orce - 12 Review activities : Air Force - 11, 14, 19, 69, 85 Preparing Activity t Air Force - 12 Civilian Agencies Interest: NAS Reviewer/user information is current as of the date of this document, For further coordination of changes to this document, draft circulation should be based on the information in the current DoD Index of Specificatfons and Standards 7 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
