1、AEROSPACE MATERIAL SPECIFICATION AMS3913 REV. B Issued 1980-10 Revised 1994-06 Reaffirmed 2014-08 Superseding AMS3913A Radome, Foam SandwichHot-Melt, Addition-Type Polyimide RATIONALE AMS3913B has been reaffirmed to comply with the SAE five year review policy. _ SAE Technical Standards Board Rules p
2、rovide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, is the sole responsibility of the
3、 user.” SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2014 SAE International All rights reserved. No part of this publication may be reproduced, stored in
4、 a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-4970 (outside USA) Fax: 724-776-0790 Email
5、: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/AMS3913B 1. SCOPE:1.1 Form:This specification covers the material and process requirements forfabricating sandwich radom
6、es having hot-melt, addition-reactionpolyimide-resin-impregnated quartz cloth shells and polyimide-resin syntacticfoam cores.1.2 Application:This product has been used typically as a radar-transparent structure for useas an electromagnetic window up to 230 C (446 F), but usage is not limited to such
7、 applications.1.3 Safety - Hazardous Materials: While the materials, methods, applications, and processes described orreferenced in this specification may involve the use of hazardous materials,this specification does not address the hazards which may be involved in suchuse. It is the sole responsib
8、ility of the user to ensure familiarity withthe safe and proper use of any hazardous materials and to take necessaryprecautionary measures to ensure the health and safety of all personnelinvolved.2. APPLICABLE DOCUMENTS:The following publications form a part of this specification to the extentspecif
9、ied herein. The latest issue of SAE publications shall apply. Theapplicable issue of other publications shall be the issue in effect on thedate of the purchase order.SAE INTERNATIONAL AMS3913B Page 2 of 14 2.1 SAE Publications:Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.AMS
10、 3138AMS 3619AMS 3698Coating Materials, Fluorocarbon (FKM) ElastomericResin, Polyimide, Laminating, High Temperature Resistant, 315 C(600 F)AMS 3709AMS 3751AMS 3755AMS 3824AMS 3844AMS 3849Adhesive Film, Hot-Melt, Addition-Type Polyimide, For Foam SandwichStructure, -55 to +230 C (-67 to +450 F)Synta
11、ctic Foam TilesMicrospheres, Hollow GlassPowder, Fumed Silicon DioxideCloth, Type “E“ Glass, Finished for Resin LaminatesCloth, Type “E“ Glass, Style 7781 Fabric, Hot-Melt, Addition-Type,Polyimide Resin ImpregnatedAMS 4770Cloth, Quartz, Style 581 Fabric, Hot-Melt, Addition-Type, PolyimideResin Impre
12、gnatedBrazing Filler Metal, Silver, 50Ag - 18Cd - 16.5Zn - 15.5Cu,1160 to 1175 F (625 to 635 C) Solidus-Liquidus Range2.2 ASTM Publications:Available from ASTM, 1916 Race Street, Philadelphia, PA 19103-1187. ASTM C 273ASTM C 297ASTM D 790ASTM D 790MASTM D 792ASTM D 2520Shear Properties in Flatwise P
13、lane of Flat SandwichConstructions or Sandwich CoresTension Strength of Flat Sandwich Constructions in FlatwisePlaneElectrical Insulating MaterialsElectrical Insulating Materials (Metric)Specific Gravity (Relative Density) and Density of Plastics byDisplacementComplex Permittivity (Dielectric Consta
14、nt) of Solid ElectricalInsulating Materials at Microwave Frequencies and Temperaturesto 1650 C.ASTM D 2584 Ignition Loss of Cured Reinforced ResinsASTM D 2734 Void Content of Reinforced Plastics2.3 U.S. Government Publications:Available from DODSSP, Subscription Services Desk, Building 4D, 700 Robbi
15、nsAvenue, Philadelphia, PA 19111-5094.MIL-STD-2073-1 DOD Materiel, Procedures for Development and Application ofPackaging Requirements3.3.1TECHNICAL REQUIREMENTS:Materials:The materials incorporated into the completed radome shall be as specifiedherein. The several styles of glass cloth specified sh
16、all conform to theapplicable requirements of AMS 3824.Flexural Properties of Unreinforced and Reinforced Plastics andFlexural properties of Unreinforced and Reinforced Plastics andSAE INTERNATIONAL AMS3913B Page 3 of 14 3.1.1 Polyimide Syntactic Foam Grout: Shall be as shown in Table 1.TABLE 1 Polyi
17、mide Syntactic Foam Grout FormulationComponent Parts by WeightAHS 3751 Glass Microspheres, Class 15 100AMS 3619 Polyimide Resin 140Fine Aluminum Powder 151/4-Inch (6.4-mm) Chopped Glass 7.2Acetone, Technical Grade 40N-Methylpyrrolidone (NMP) 553.1.2 Polyimide Surface Filler: Shall be as shown in Tab
18、le 2.TABLE 2Polyimide Surface Filler FormulationComponent Parts by WeightFine Inorganic FillerN-Methylpyrrolidone (NMP)40AMS 3619 Polyimide Resin 60AMS 3755 Fumed Silicon Dioxide Powder 13.2 Procedure:3.2.1 Mandrel Preparation: The mandrel on which the shell is to be built shall(R)be cleaned with a
19、suitable organic solvent and coated with an appropriate release agent.3.2.2 Bare Mandrel Calibration:3.2.2.1 The mandrel shall be centered in the grinder with a maximum deviation of0.0007 inch (0.018 mm) total indicator reading (TIR) at the base.3.2.2.2 Using the gaging system on the appropriate gri
20、nder, bare mandrel readingsrelative to the master cam shall be measured to the nearest 0.0010 inch(0.025 mm) at the appropriate stations.3.2.3 General Fabrication Procedures: Fabrication of the radome shell shall beaccomplished in the following sequence: (1) layup and cure the inner skin and solid l
21、aminate buildups, (2) bond, grout, and grind precured foam core, (3) layup and cure the outer skin, and (4) postcure, final grind, trim, andassemble finished radome (e.g., nose plug, lightning diverters, erosioncoating).80SAE INTERNATIONAL AMS3913B Page 4 of 14 3.2.3.13.2.3.23.2.3.3Skin Layup: The w
22、arp direction of the resin-impregnated fabric shall beparallel to the radome centerline 10 degrees. Lap joints shall not besuperimposed. Lap joints shall be 0.50 inch 0.25 (12.7 mm 6.4) wide.The layup temperature shall not exceed 70 C (158 F) prior to the curingoperation.Layup Debulk: The uncured la
23、yup shall be debulked, after each ply orseries of plies is laid up, as required to eliminate wrinkles in thecured skin. Debulking may be accomplished by vacuum bag, wrapping withcord under tension, or by use of shrink tape. Temperatures duringdebulking operations shall not exceed 70 C (158 F).Cures:
24、 All autoclave cures shall be carried out in a vacuum bag. Thereshall be at least one thermocouple buried within the layup to be cured,no more than one ply from the mandrel side of the uncured layup, andlocated in the base overtrim. As the coolest thermocouple during heatup,this shall be the control
25、ling thermocouple. Not less than fourthermocouples shall be taped to the outer surface of the vacuum bag,located at the base trim, at the nose, and at two intermediate locationsbetween these. These thermocouples shall be insulated from the air withpads of glass insulation. Where vacuum is specified,
26、 the vacuum pressureshall be not less than 24 inches (610 mm) of mercury (Hg). There shallbe three vacuum lines, one at the nose and two, 180 degrees apart, at theradome base.3.2.4 Inner Skin Fabrication:3.2.4.1 Layup: Six plies of AMS 3849 resin-impregnated quartz cloth shall belaid up on the mandr
27、el in accordance with 3.2.3.1.3.2.4.2 Preparation for Cure: A peel ply shall be used over the lay-up only (donot connect with bleeder system), and the entire assembly vacuum-baggedusing nylon film. A non-perforated film and dry glass fabric “breather“ply between the peel ply and bag shall be used. B
28、leeder system shall besuch that bleeding is through the top surface of the lay-up only and notfrom the edges.3.2.4.3 Cure: The assembly shall be placed in an autoclave for cure. Vacuum notless than 24 inches (610 mm) Hg shall be applied and maintainedthroughout the cure cycle. The assembly shall be
29、heated to a temperaturewithin the range 82 to 93 C (180 to 199 F) and held at the selected temperature within 5 C (9 F). Autoclave pressure of 90 psi 5(621 kPa 34) shall be applied and the temperature increased to180 C 5 (356 F 9). Assembly shall be cured for not less than90 minutes at 180 C 5 (356
30、F 9) and 90 psi 5 (621 kPa 34).During cool-down, autoclave pressure shall be maintained until part hascooled below 120 C (248 F) and vacuum shall be maintained on assemblyuntil it has cooled below 90 C (194 F).3.2.5 Solid Laminate Layup:3.2.5.1 The unfinished glass fabric, Style 128 or 7628, peel pl
31、y, shall bestripped from the part in the buildup areas.SAE INTERNATIONAL AMS3913B Page 5 of 14 3.2.5.2 Sufficient plies of AMS 3844 Style 7781, E-glass, hot-melt,addition-type, polyimide-resin-impregnated fabric shall be laid up overthe aft section of the inner skin to obtain the cured thickness spe
32、cifiedon the drawing, plus not less than two excess plies. Patterns may bebias-cut relative to the radome axis. The nose area buildup shall be cutand laid up as shown on the drawing, using AMS 3849 resin-impregnatedcloth.3.2.5.3 The solid buildup layups shall be debulked in accordance with 3.2.3.2,v
33、acuum bagged in accordance with 3.2.3.3, and autoclave cured inaccordance with 3.2.4.3.3.2.6 Preparation of Foam Core Tiles: The foam tiles shall be fabricated inaccordance with AMS 3709 to the requirements of the applicable drawing.3.2.7 Bonding of Tiles to Inner Skin:3.2.7.13.2.7.23.2.7.33.2.7.4Th
34、e remaining 128 or 7628 glass peel ply shall be removed from the innerskin. A ply of AMS 3698 polyimide adhesive film shall be applied to thepeeled area.The prepared tiles from 3.2.6 shall be positioned on the inner skin inaccordance with the applicable drawing so that there is a gap of0.150 inch 0.
35、030 (3.81 mm 0.76) around each tile.One layer of glass bleeder fabric shall be laid over the entireradome/tiles surface, the part shall be vacuum bagged, and a vacuum ofnot less than 24 inches (610 mm) Hg shall be applied.The part shall be placed in an autoclave and cured as follows:simultaneously r
36、aise the autoclave air temperature to 185 C 2(365 F 4) at a rate of 1.5 to 2.0 C (2.5 to 3.5 F) degrees per minutecoolest-part thermocouple reaches 170 C (338 F), the part shall bemaintained at 180 C 5 (356 F 9) for not less than 90 minutes. Thepart shall be cooled to 100 C (212 F) or below under va
37、cuum and atleast 50 psi (345 kPa) pressure before debagging.3.2.8 Core Joint Grouting:3.2.8.1 Open all joints to 0.19 inch 0.06 (4.8 mm 1.5) at the base and taperthe sides to an angle approximately 10 degrees from normal to the radomesurface.3.2.8.2 Apply a thin coat of AMS 3619 polyimide resin to a
38、ll joint surfaces.3.2.8.3 Prepare grout mix in accordance with 3.1.1.3.2.8.4 Pack grout mix into all foam tile joints.3.2.8.5 Raise radome temperature to 65 C 2 (149 F 4) and hold at heat for60 minutes 5. Cool to room temperature.and raise the pressure to not less than 50 psi (345 kPa). When theSAE
39、INTERNATIONAL AMS3913B Page 6 of 14 3.2.8.6 One ply of glass release/bleeder fabric shall be placed over all filledjoints. Vacuum bag the part and apply a vacuum of not less than24 inches (610 mm) mercury.3.2.8.7 Heat the radome to 115 C 5 (239 F 9) and hold at temperature fornot less than 45 minute
40、s; raise radome temperature to 175 C 5(347 F 9), and hold for not less than 90 minutes. Cool the radomeunder full vacuum to below 65 C (149 F) before debagging.3.2.9 Pregrind: The part shall be centered in the grinder with a maximumdeviation of 0.0007 inch (0.018 mm) total indicator reading (TIR) at
41、 thenose and a maximum of 0.0010 inch (0.025 mm) TIR at the base. The foamcore window areas shall be ground to the total wall thickness shown on thedrawing, -0.082 inch (-2.08 mm), +0. The solid laminate base area shall beground to the total thickness shown on the applicable drawing, -0.072 inch(-1.
42、83 mm), +0. After grinding, the radome surface shall be vacuumcleaned.3.2.10 Outer Skin Layup:3.2.10.1 At least two plies more than the six required for the final outer skinshall be laid over the entire surface of the radome using AMS 3849resin-impregnated cloth.3.2.10.2 The outer skin layup shall b
43、e fitted with not less than fourautoclave cured in accordance with 3.2.4.3.3.2.11 Postcure: The radome shall be fitted with not less than fourthermocouples taped to the outer surface and located at the base, at thenose, and at two intermediate locations between. The thermocouples shallbe insulated f
44、rom the surrounding medium to reflect the radomerecorded on the coolest thermocouple.3.2.11.1 Temperature shall be uniformly increased in stages to 190 C 5(374 F 9) over a 2-hour 0.1 period and maintained at temperaturefor not less than 12 hours.3.2.12 Final Grind: The radome window area shall be gr
45、ound to the electricaldesign configuration as determined with a one-horn interferometer. Baseattach area and nose area shall be ground to the dimensional requirementsof the applicable drawing.3.2.13 Coating and Assembly of Radome:3.2.13.1 The radome shell shall be removed from the mandrel using an a
46、ppropriateremoval tool.3.2.13.2 All tooling and drain holes shall be drilled as specified on theapplicable drawing.3.2.13.3 The radome shell shall be trimmed and routed, as specified on theapplicable drawing, using the proper trim fixture.temperature. The radome shall be postcured in accordance with
47、 3.2.11.1 asSAE INTERNATIONAL AMS3913B Page 7 of 14 3.2.13.4 Surface Sealing:3.2.13.4.1 The polyimide filler of 3.1.2 shall be applied to the exterior shellsurfaces and to all cut or drilled laminate edges. The radome shallbe heated to 175 C 5 (347 F 9) at a rate of 2 to 3 C (4 to 5 F)degrees per mi
48、nute, cured for 60 minutes 5 at 175 C 5(347 F 9), and cooled to room temperature.3.2.13.4.2 All radome surfaces shall be lightly sanded with No. 100 to 180(R) (150 to 80 mm) grit sandpaper to remove the gloss. The dust shall beremoved by using clean cheesecloth dampened with a suitable cleaningsolve
49、nt. Silicone resin shall be diluted for spraying with a 3 to 1by weight mixture of xylene. All interior radome surfaces shall besprayed to a dry film thickness of 0.001 to 0.002 inch(0.025 to 0.051 mm). The radome shall be heated to 175 C 5(347 F 9) at a rate of 2 to 3 C (4 to 5 F) degrees per minute,cured for 60 minutes 5
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