1、_ SAE Technical Standards Board Rules provide 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 there
2、from, is the sole responsibility of the 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 2013 SAE International All rights reserved. No part of this p
3、ublication may be reproduced, stored in 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: +1 724-776-497
4、0 (outside USA) Fax: 724-776-0790 Email: 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/AMS2521C AEROSPACE MATERIAL SPECIFICATION AMS2521 REV. C Issued 1967-11 Revised 2
5、001-04 Reaffirmed 2013-11 Superseding AMS2521B Coating, Reflection-Reducing for Instrument Glasses RATIONALE AMS2521C has been reaffirmed to comply with the SAE five-year review policy. 1. SCOPE:1.1 Form: This specification covers optical-quality coatings applied to instrument glasses.1.2 Applicatio
6、n: This coating has been used typically to reduce the intensity of reflection from the surfaces of instrument glasses and to increase light transmission through the glasses, but usage is not limited to such applications.2. APPLICABLE DOCUMENTS: The issue of the following documents in effect on the d
7、ate of the purchase order forms a part of this specification to the extent specified herein. The supplier may work to a subsequent revision of a document unless a specific document issue is specified. When the referenced document has been canceled and no superseding document has been specified, the
8、last published issue of that document shall apply.2.1 SAE Publications: Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.ARP924 Specification and Inspection of Glass for Integrally Lighted Aerospace InstrumentsSAE INTERNATIONAL AMS2521C Page 2 of 8 2.2 ASTM Publications: Availab
9、le from ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959.ASTM B 117 Operating Salt Spray (Fog) Testing ApparatusASTM D 1003 Haze and Luminous Transmittance of Transparent PlasticsASTM E 11 Wire-Cloth Sieves for Testing PurposesASTM G 21 Determining Resistance of Synthetic Polymeric Mate
10、rials to Fungi2.3 U.S. Government Publications: Available from DODSSP, Subscription Services Desk, Building 4D, 700 Robbins Avenue, Philadelphia, PA 19111-5094.MIL-E-12397 Eraser, Rubber-Pumice (for Testing Coated Optical Elements)MIL-STD-1241 Optical Terms and Definitions2.4 U.S. Army Drawings: Ava
11、ilable from Commander, U.S. Army, TACOM-ARDEC, Attn: AMSTA-AR-QAW-E, Picitinnay Arsenal, NJ 07806-5000.D7680606 Coating, Eraser Abrasion Tester3. TECHNICAL REQUIREMENTS: 3.1 Material: The composition of the coating material shall be optional with the coating vendor.3.2 Properties of the Applied Coat
12、ings: The coating, applied to substrate materials having indices of refraction within the range 1.47 to 1.55, shall conform to the following requirements. Tests shall be performed on the coated parts or on coated glass witness specimens of the same index of refraction and surface finish as the subst
13、rate for the coated parts, coated in the same evaporation run as the parts, and positioned in the chamber so as to represent the optical and durability characteristics of the parts.3.2.1 Spectral Properties: 3.2.1.1 Specular Reflectance: The specular reflectance from each coated surface, measured wi
14、th a calibrated spectrophotometer as defined in ASTM D 1003, shall not exceed the following limits for energy incident on the surface at the angles shown in Table 1.SAE INTERNATIONAL AMS2521C Page 3 of 8 3.2.1.2 Light Absorption: Within the wavelength range 425 to 700 millimicrons (nm), light loss s
15、hall not exceed the limits per surface shown in Table 2, determined with a calibrated spectrophotometer as defined in ASTM D 1003:3.2.2 Durability: The coating, subjected to the adhesion test of 4.5.1 followed by the abrasion resistance test of 4.5.2, shall show no evidence of peeling, flaking, crac
16、king, crazing, or delamination and shall have no change in spectral characteristics resulting in nonconformance to the requirements of 3.2.1.3.2.3 Environmental Resistance: The coating shall show no change in spectral characteristics resulting in nonconformance to the requirements of 3.2.1 after exp
17、osure to any of the following:3.2.3.1 Elevated temperature in accordance with 4.5.3.3.2.3.2 Sand and dust in accordance with 4.5.4.3.2.3.3 Fungus in accordance with 4.5.5.3.2.3.4 Thermal shock in accordance with 4.5.6.3.2.3.5 Continuous exposure to salt spray in accordance with ASTM B 117 for not le
18、ss than 50 hours.3.2.3.6 Humidity in accordance with 4.5.7. After exposure, the coating, lighted and inspected in accordance with ARP924, shall show no evidence of a cloudy or hazy appearance.TABLE 1 - Specular ReflectanceWavelength RangeMillimicrons (nm)Reflectance, %, maximumFor Angle of Incidence
19、 Shown0 to 15 degrees, inclReflectance, %, maximumFor Angle of Incidence Shown30 degrees 0.5450 to 675, incl 0.6 absolute -450 to 650, incl - 1.0 absolute500 to 620, incl 0.35 average 0.50 average425 to 700, incl 0.35 average 0.50 averageTABLE 2 - Light Loss LimitsValue PercentMaximum average absorp
20、tion 0.5%Maximum absolute absorption 2.0%SAE INTERNATIONAL AMS2521C Page 4 of 8 3.3 Quality: The coating, as received by purchaser, shall be uniform in quality and condition, smooth, and free from foreign materials and from physical and optical imperfections detrimental to performance of parts, dete
21、rmined in accordance with ARP924.3.3.1 Surface Imperfections: Imperfections in the clear aperture area of the coating, as defined in MIL-STD-1241, shall not exceed the limits, shown in Table 3, evaluated in accordance with ARP924:4. QUALITY ASSURANCE PROVISIONS: 4.1 Responsibility for Inspection: Th
22、e vendor of the coating shall supply all samples for vendors tests and shall be responsible for the performance of all required tests. Purchaser reserves the right to sample and to perform any confirmatory testing deemed necessary to ensure that the coating conforms to the requirements of this speci
23、fication.4.2 Classification of Tests: 4.2.1 Acceptance Tests: Specular reflectance (3.2.1.1), light absorption (3.2.1.2), durability (3.2.2), salt spray resistance (3.2.3.5), humidity resistance (3.2.3.6), and quality (3.3) are acceptance tests and shall be performed on each lot.4.2.2 Preproduction
24、Tests: All technical requirements of this specification are classified as preproduction tests and shall be performed prior to or on the initial shipment of coated parts to a purchaser, when a change in material and/or processing requires reapproval as in 4.4.2, and when purchaser deems confirmatory
25、testing to be required.4.3 Sampling: Shall be not less than the following; a lot shall be all parts made of the basis material, coated in the same equipment in a single pump-down cycle, and presented for vendors inspection at one time.TABLE 3 - Surface Imperfection LimitsArticle Scratch SpatterPinho
26、le,Void, or LintWindow #80 #50 #50Cover glass orcover wedge #60 #20 #40Lighting wedge #40 #20 #40SAE INTERNATIONAL AMS2521C Page 5 of 8 4.3.1 For Acceptance Tests: One part or one witness specimen for each requirement. 4.3.2 For Preproduction Tests: Thirty parts or witness specimens, five for each r
27、equirement except that the durability and humidity resistance tests shall be performed on the same five specimens and all 30 specimens shall be inspected for conformance to quality requirements.4.4 Approval: 4.4.1 Sample coated parts shall be approved by purchaser before coated parts for production
28、use are supplied, unless such approval be waived by purchaser. Results of tests on production coated parts shall be essentially equivalent to those on the approved samples.4.4.2 Vendor shall use ingredients, manufacturing procedures, processes, and methods of inspection on production coated parts wh
29、ich are essentially the same as those used on approved sample parts. If necessary to make any change in ingredients, in type of equipment for processing, or in manufacturing procedures, vendor shall submit for reapproval a statement of the proposed changes in ingredients and/or processing and, when
30、requested, sample coated parts. Production parts coated by the revised procedure shall not be shipped prior to receipt of reapproval.4.5 Test Methods: 4.5.1 Adhesion: Test specimens shall be clean and free from contaminants, including finger prints, that would affect the adhesion of the testing tape
31、. A strip of pressure-sensitive tape, 1 inch (25 mm) in nominal width or approximately 2/3 of the least dimension of the test specimen if less than 1 inch (25 mm), shall be pressed firmly in contact across the entire coated surface. After 30 to 60 seconds the tape shall be removed quickly with a sna
32、p action which exerts the greatest possible stripping effect on the surface.4.5.2 Abrasion Resistance: 4.5.2.1 Test Procedure: The coating shall be tested by holding a standard abrasion testing device in the hand and rubbing the coated surface with a standard eraser conforming to MIL-E-12397 mounted
33、 in the holding device. A pressure of approximately 2.0 to 2.5 pounds force (8.9 to 11.1 N) shall be applied. Strokes of approximately 1 inch (25 mm) shall be made if the size of the element or specimen will permit it; smaller strokes for smaller specimens. All strokes shall be made on one path for
34、20 complete strokes.4.5.2.2 Test Equipment: Assembly details of the Abrasion Tester may be obtained on written request from U.S. Army Armament Research and Development Command as indicated in 2.3. The only rubber eraser plug which is acceptable for this test is also available from the same source. A
35、ll requests should make reference to Drawing D7680606.4.5.3 Elevated Temperature: Specimens shall be heated to 315 C 8 (599 F 14), held at temperature for not less than 15 minutes, and cooled to room temperature. Heating and cooling rates shall be not greater than 8 C (14 F) degrees per minute.SAE I
36、NTERNATIONAL AMS2521C Page 6 of 8 4.5.4 Sand and Dust Resistance: 4.5.4.1 Test Chamber: The chamber shall consist of a dust-tight cabinet with the floor designed to permit the dust to fall into hoppers for recirculation. The facility shall be time-cycle-controlled to accomplish the exposure and shut
37、down required. A blower and duster shall be provided to circulate the dust throughout the test chamber with the velocity and concentration outlined.4.5.4.2 Test Procedure: The test samples shall be placed in the test chamber and the sand and dust density raised to, and maintained at, 0.1 to 0.5 gram
38、/cubic foot (3.5 to 17.7 g/m3) and velocity between 100 and 500 feet/minute (508 and 2540 mm/s) within the test space. The internal temperature of the test chamber shall be maintained at 25 C 5 (77 F 9) for not less than six hours then raised to and maintained at 70 C 3 (158 F 5) for not less than s
39、ix hours additional. The relative humidity shall not exceed 30% at any time during the test. At the end of the exposure period, the sample shall be removed from the test chamber and allowed to cool to room temperature. Accumulated dust shall be removed by brushing, wiping, shaking, or blowing with c
40、lean, dry air.4.5.4.3 Sand and Dust: Sand and dust used in the test shall be of angular structure and shall have characteristics as follows:4.5.4.3.1 Particle Size: Shall be as follows, determined using U.S. Standard Sieve Series or equivalent as defined in ASTM E 11:100% shall pass through a 100 me
41、sh (150-m) sieve.98% 2 shall pass through a 140 mesh (106-m) sieve.98% 2 shall pass through a 200 mesh (75-m) sieve.75% 2 shall pass through a 325 mesh (44-m) sieve.4.5.4.3.2 Chemical Composition: Shall be as shown in Table 4, determined by wet chemical methods or by a method acceptable to purchaser
42、:TABLE 4 - CompositionIngredient% by Weightminimum% by WeightmaximumSi02 97 99Fe203 - 2A1203 - 1Ti02 - 2Mg0 - 1Ignition - 2SAE INTERNATIONAL AMS2521C Page 7 of 8 4.5.5 Fungus Resistance: Testing shall be conducted in accordance with ASTM G 21, using one species of fungus from each of the groups show
43、n in Table 5.4.5.6 Thermal Shock: Test specimens shall be heated to, and maintained at, 70 C 3 (158 F 5) for not less than one hour and immediately thereafter placed in direct contact with an ice cube at least one square inch (645 mm2) in area for not less than two minutes. 4.5.7 Humidity Resistance
44、: Test specimens shall be exposed continuously for not less than 24 hours in an atmosphere of 98% 2 relative humidity at 50 C 2 (122 F 4).4.6 Reports: 4.6.1 The vendor of coated parts shall furnish with each shipment a report showing the results of tests to determine conformance to the acceptance te
45、st requirements and stating that the coating conforms to the other technical requirements of this specification. This report shall include the purchase order number, AMS 2521C, vendors material or product designation, lot number, size or part number, and quantity.4.7 Resampling and Retesting: If any
46、 specimen used in the above tests fails to meet the specified requirements, disposition of the product may be based on the results of testing three additional specimens for each original nonconforming specimen. Failure of any retest specimen to meet the specified requirements shall be cause for reje
47、ction of the product represented. Results of all tests shall be reported.5. PREPARATION FOR DELIVERY: 5.1 Coated parts shall be handled and packaged in such a manner as will ensure that the required physical characteristics of the coating are preserved.TABLE 5 - Fungus SpeciesGroup OrganismAmerican
48、TypeCulture Collection No.QuartermasterNumberI Chateomium globosumMyrothecium verrucaria62059095459460II Memneniella echinataAspergillus niger959762751225458III Aspergillus flavusAspergillus terreus1083610690122382jIV Penicillium citrinumPenicillium ochrochloron984991121226477SAE INTERNATIONAL AMS25
49、21C Page 8 of 8 5.2 Packages of coated parts shall be prepared for shipment in accordance with commercial practice and in compliance with applicable rules and regulations pertaining to the handling, packaging, and transportation of the coated parts to ensure carrier acceptance and safe delivery.6. ACKNOWLEDGMENT: A vendor shall mention this specification number and its revision lett
