1、L MIL-M-24041C 73 m 7777706 0118372 2 W MIL-M-24041C 17 August 1981 SUPERSEDING 15 August 1975 and 20 October 1972 (See 6.6) MIL-M-O02. Nonvolatile content of the molding compound shall be not less than 99 percent, when tested as specified in 4.7.2.1. 3.5.2 Initial dynamic viscosity. A mixed type 1
2、compound shall have a viscosity not greater t.han 400 poises, nor less than 100 poises., when determined as specified in 4.7.2.2. Type II compound shall have a viscos- ity not greater than 700 poises, nor less than 250 poises, when determined as specified in 4.7.2.2. 3 1 i Provided by IHSNot for Res
3、aleNo reproduction or networking permitted without license from IHS-,-,-MIL-M-24041C 3.5.3 Application life. Application life of the type I compound shall be not less than 1 hour, when tested as specified in 4.7.2.3.1. Type LI compound shall have an application life of not less than 1/2 hour, when t
4、ested as specified in. 4.7.2.3.2, 3,5.4 Total.or ultimate cure time. The Shore llAll hardness of the material shall bnot less than 70 when cured for the periods as shown in table I, and when tested as specified in 4.7.2.4. TABLE I. Total curing time. - W Time Requirements Tempgrature Relative humidi
5、ty F “ 16 hours Shore aAfl hardness, 77OF 50 + 5 percent 3 weeks Shore II A11 hardness, 180 + 2F 50 + 5 percent - 70 minimum I 70 minimum 3.5.5 Storage life. Type I material and primer shall meet the requirements of thisospecification for 12 months from date of manufacture when St6red below 80 F in
6、the original unopened containers. Type II materials shall meet the requirements of this specification for 28 days at minus 40 F after receipt of material. 3.6 Mechanical and physical properties. Mechanical and physical properties of the totally cured compound shall be in accordance with table II, wh
7、en tested as specified in 4.7.3. TABLE II. Mechanical and physic-al properties. Property I I Units Requirements L- I I Shrinkage Specific gravity Shore IIA“ hardness Tensile strength Ultimate elongation Tear strength Compression set Adhesion: To metal To rubber To polyvinylchloride Moisture absorpti
8、on Low temperature flexibility Percent “ Lb/in percent Lbs/in Percent - 2 Lbs/in of width Pegcent F 4 5 maximum 1. O minimum 1.2 maximum 2,500 minimum 400 minimum 150 minimum 55 maximum 70-92 50 minimum 15 minimum 15 minimum 3 maximum -65 maximum Test paragraph 4.7.3.3 4.7.3.5 4.7.3.6 4.7.3.7 4.7.3.
9、4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TABLE II. Mechanical and phys3cal- properties. Continued Property . Units Heat aging- “ Shore IIA“ hardness loss at 275F for 24 hours Property degradation Fungus resistance Percent Hydrolytic stabilit
10、y Percent Ozone resistance “ “ Shore-,llA1l hardness loss Requirements. Test paragraph -7 maximum 4.7.3.11 50 maximum . Non-nutrient -20 maximum 4.7.3.12 4.7.3.13 4.7.3.14 i No Cr ao ki ng 4.7.3.15 3.7 Electrical properties. Electric,al properties of the totally cured molding and potting compound sh
11、all be in accordance with table III, when tested as specified in 4.7.4. TABLE TIT. Electri Property I -Units .Resistance to arc Dielectric strength Dielectric constani: 1 kilohertz at 77,F. 1 megahertz at 77 F 1 kilohertz at 77zF 1 megahertz at 77 F Volumeoresistivity . Power factor: at 77 g at 250
12、F at 77 g at 250 F Insulation resistance: Initial at 77:F at 250 F After hydrolytic stability test High potential Flame resistance Surfacg resistivity overload Seconds Bolts/mil . -1 -c “ “ Ohm - CMS Ohms Megohms I l/Based on average compound properties al properties. - I/ Requirements Test paragrap
13、h 50 minimum 250 minimum 1 O maximum 8 maximum 0.08 maximum 0.10 maximum 4.7.4.1 4.7.4.2 4.7.4.3 , 467.4.3 4.7.4.3 4.7.4.3 4 X 10 minimum 4.7.4.4 2.5 X 10 minimum 4.7.4.4 9 2.4 X IO:* minimum 4.7.4.4 2.4 X 10 minimum 4.7.4.4 300,000 minimum 4.7.4.5 .I O0 minimum 4.7.4.5 4.-7.3.14.1 1 O00 minimum No
14、breakdown 4.7.4.6 Shall not ignite 4.7.4.7 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4. QUALITY ASSURANCE PROVISIONS sibility for in.spection. Unless otherwise specified in e contractr is responsible for the performance of all inspection requir
15、ements as specified herein. Except as otherwise specified in the contract, the contractor may use his own or any other facilities suitable for the performance of the inspection requirements specified herein, unless disapproved by the Government, The Government reserves the right to perform any of th
16、e inspections set forth-in-the specification where such inspections are deemed necessary to assure supplies and services conform to prescribed requirements. 4.2 C.lass,ification 0.f inspections. The inspection requirements specified herein are classified as follows: (a) Qualification inspection (see
17、 4.3). (b) Quality conformance inspection (see 4.4). 4.3 Qualification in-spection. Qualification inspection shall be conducted at a laboratory satisfactory to the Naval Sea Systems Command. Qualification inspection shall consist of the examination and tests specified in 4.7. 4.3.1 Samples for quali
18、fication tests;Qual,ification test samples shall consist of x least 5 quarts of base compound, together with the necessary curing agent and primer. The base compound and curing agent shall be furnished in containers of the type to be used in filling contract orders, After successfully conforming to
19、all the requirements of this specification, approval of the material will be granted, and will be identified by reference to the manufacturerIs.code or formula number. Samples shall be identified as follows: SAMPLES FOR QUALIFICATION TESTS Molding and Potting Compound, Chemically Cured, Polyurethane
20、. Specification MIL-M-24041. Category No. Type No. Name of manufacturer and address of plant which produced qualification sample I Manufacturers code no, or formula no. Manufacturers code no, or formula no. of primers. for adhesion tests. Submitted by (name) (date) for qualification tests in accorda
21、nce with the requirements of Military Specification MfL-M-2404:l under authorization (reference authorizing letter). . 6 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-M-24041C 43. m 7777706 0338378 3 m MIL-M-24041C Date of manufacture. Mixing i
22、nstructions. Manufacturers data. 4.3.2 manufacturer? data. Two copies of the manufacturers instructions for the mixing and application of the compound, to be identical in content to those instructions required in 5.1.3 and two copies of the manufacturers test report, containing data showing that mat
23、erial submitted for qualification conforms to th qualification requirements of this specification, shall be submitted simultaneously with qualification samples. 4.4 Quality conformance tests. 4.4.1 Inspection lot. A lot shall consist of all compound manufac- tured as one batch and offered for delive
24、ry at one time. 4.4.2 Sampling. 4.4.2.1 Sampling far inspection of material. Enough containers shall be selected at random to form two separate specimens These containers shall be sealed, marked, and held for testing of the material. Specim.ens shall be subjected separately to the following tests. I
25、f either specimen fails one or more of these tests, this shall be cause for rejection of the lot. (a) Examination of product (see 4.7.1) (b) Viscosity (see 4.7.2.2) (c) Application life (see 4.7.2.3) (d) Cure time (at 180F only) (see 4.7.2.4) (e) Hardness (see 4.7.3.3) 4.4.2.2 In addition, the produ
26、ct shall be subjected to any of the other tests specified herein which the contracting activity considers necessary to determine conformance with the requirements of this specification. 4.5 Government production control tests. Government production control tests as considered desirable may, at the o
27、ption of the contracting activity, be conducted on samples selected from a batch of molding compound. Samples shall be furnished by the manufacturer. 4.6 Test conditions. . 4.6.1 Test specimen preparation. 4.6.1.1 Mixing of type I molding material. Type I material curing agent may solidify when subj
28、ected to temperatures below 65 F, When this condition exists, liquefy the curing agent in accordance with manufac- turers instructions. After liquefication-is complete, allow the curing agent to cool to 77OF 2 2F. The two curing agents shall be thoroughly mixed in the proper proportions in either a
29、mjxing machine designed for this application, or in a metal, polyethylene, or glass container having approximately twice the volume of material. Mixed material shall be degassed under a vacuum in a period of less than 20 minutes. O 7 Provided by IHSNot for ResaleNo reproduction or networking permitt
30、ed without license from IHS-,-,-MIL-M-24041C 4.6.1.2 Thawing of type II material. Premixed, frozen cartridges of molding compound shall be thawed in accordance with the manufacturers - 4.6.1.3 Molding and potting. Molds for disc specimens and special shapes as indicated in individual test descriptio
31、ns shall be of poly- ethylene or of a Teflon-coated metal or equal sprayed with a silicone release agent or of any other composition having a-nonadhesive surface which will not transfer to the test specimen. The mold shall be con- structed to facilitate easy removal of the specimen. Panels of the si
32、ze and composition indicated in individual test descriptions shall be designed for coating by suitable mold insertion or coating technique. Panels shall be thoroughly cleaned with a suitable solvent and dried, prior to the application of the primer and molding compound. Molding compound shall be pou
33、red or extruded slowly into the mold until a slight excess is obtained. The mold shall then be covered with a flat, smooth plate and a pressure not to exceed 10 pounds per square inch (lb/inL) applied. 4.6.1.4 Curin 1 an“d. 4.7:3.8 1.2 shall be tested as follows: Two I-inch wide strips shall be cut
34、length- wise through the screen and compound to the panel surface and extended the full length of the loose end of the screen. . Edges of the panel sh.all not be used as one edge of the test strip. The panel shall 6e testd indivi-. dually in an autographic testing machine with a capacity sch thatthe
35、 tension at failure is not more than 85 percent nor less than 15 percent of the full scale load. Rate of separation of the jaws.shal1 be 2 inches per minute and shall be uniform at all times. Specimens shali be mounted i.n the machine so that the loose end of the I-inch widescreen st;ri.p will be- f
36、olded 180 degrees as it is pulled from the panel. Each strip sh.all be“ pulled as follows: A cut through the compound to th-e panel at the junction of separation shall be made at an angie of 45 degre.es-in ,t“ directi-on of; separation. If a cohesive failure develops or if the compoundseparate-s fro
37、m the screen, similar 45-degree cuts shall be made as necessary to promote separation of the compound from the panel. Adhesion. in pounds shall be automatically recordedon a chart as a continuous curve. Adhesion value shall be calculated by averaging the maximum and minimum forces required to separa
38、te the compound from the panel. If cohesive failures occur, the adhesion value shall be reported as greater than the measured value. 11 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. “ . MIL-M-24043C 93 993790b 0338403 3 a MIL-M-24041C 4.7.3.8.2 A
39、dhesion of compound to neoprene. 4.7.3.8.2.1 Preparation of qpecimens. Two 3-inch by 6-inch by 0,125-inch thick sheets of rubber conforming to MIL-R-3065, and used for cables conforming to MIL-C-915 shall be abraded on one side with 80 grit sandpaper and wiped clean with dry gauze. Rubber sheets wit
40、h abraded side up shall be supported by 3-inch by 6-inch by 0.032-inch thick metal sheets attached to the unabraded side with double-faced pressure sensitive tape conforming to UU-T-91. A thin coat of the recommended primer shall be applied to the abraded surfaces in accordance with the manufacturer
41、s instructions, and allowed to dry. Primed surfaces of rubber sheets shall be placed facing each other, separated by two 1/8-inch thick spacers along the 6-inch edges. The two sheets shall be taped together along the 6-inch edges and one of the 3-inch edges. Extrude freshly mixed molding compound in
42、io the cavity filling it to within 1 inch of the-top of the assembly. Cure material in accordance with 4.6.1.4 and cut two l-inch by 6-inch strips from the test specimen assembly. Outside cuts shall be parallel and approximately 1/2 inch from the lengthwise edge of the assembly. 4.7.3.8.2.2 Te,sting
43、 of adhesion of compound to neoprene. Loose ends of the rubber specimen which are left by filling the assembly to within 1 inch of the top in 4.7.3.8.2.1 shall be attached to opposite g S of an autographic tensile testing machine with a capacity such that tension at failure shall not be more than 85
44、 percent nor less than 15 percent of t.he full scale. Rate of grip separation shall be 2 inches per minute and shall be uniform at all times, Adhesion in pounds shall be automatically recorded on a chart as a continuous curve for a minimum of 6 inches of grip separation. Adhesion value shall be calc
45、ulated by averaging the maximum and minimum forces required to separate the compound from the rubber. 4.7.3.8.3 Adhesion of compound to polyvinyl chloride. 4.7.3.8.3.1 P,reparation of specimens. Two 3-inch by 6-inch by 0,125-inch thick sheets of polyvinyl chloride conforming to MIL-1-7444 shall be p
46、repared for priming by applying methyl ethyl ketone to one side of each strip to make the surface tacky. A thin coat of recommended primer shall be applied to the tackified surface in accordance with the manufac- turers instructions and allowed to dry, Primed surfaces of the polyvinyl chloride sheet
47、s shall be placed facing each other separated by two 1/8-inch thick spacers along the 6-inch edges and one of the 3-inch edges. Extrude freshly mixed molding compound into the cavity filling it to within 1 inch of the top of the assembly. Cure material in accordance with 4.6.1.4 and cut two l-inch b
48、y 6-inch strips from the test specimen assembly. Outside cut9 shall be parallel to and approximately 1/2 inch from the lengthwise edge of the assembly. 4.7.3.8.3.2 of adhesion of cmto polyvinyl chloride. Polyvinyl chloride specimens shall be tested in accordance with 4.7.3.8.2.2. to 12 Provided by I
49、HSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-M-24041C 4.7.3.9 Moisture absorption. A sp.ecimen, 1.0 inch by 1.0 inch by 1.0 inch, shall be molded in accordance with 4.6.1. The specimen shallobe weighed and immersed for 24, hours in a _distilled water bath held at 200- F I + 5OF. The specimen shall be removed, ,b.lotted dry -and weighed. The percent of water abso
