SAE AIR 1364A-1995 Age Control of Age Sensitive Elastomeric Materials《易老化的人造橡胶材料的老化控制》.pdf
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1、 AEROSPACE INFORMATION REPORT Age Control of Age Sensitive Elastomeric Materials 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 suita
2、bility for any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user. SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyri
3、ght 2003 SAE International All rights reserved. No part of this publication 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 ORD
4、ER: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA) Fax: 724-776-0790 Email: custsvcsae.org SAE WEB ADDRESS: http:/www.sae.org Issued 1975-05 Revised 1995-11 Reaffirmed 2003-12 Superseding AIR1364 AIR1364 REV.A (R) FOREWORD MIL-STD-1523A, Age Controls of Age-Sensitive Elast
5、omeric Materiel, requiring maximum ages of age sensitive elastomeric items for use in military aircraft and missiles and for space vehicles at the time of acceptance, was canceled on 30 January 1995. U.S. military specifications for nitrile rubber O-rings such as MIL-P-5315, MIL-P-5510, MIL-P-25732,
6、 and MIL-P-83461 which were formerly controlled by MIL-STD-1523A are now released from age control. Certain hoses containing nitrile rubber continue to be age controlled by AS1933A, Age Controls for Hose Containing Age-Sensitive Elastomeric Material. The following text is unchanged from the 1975 rev
7、ision (except where indicated) and is republished for historical purposes. 1. SCOPE: This SAE Aerospace Information Report (AIR) summarizes data and background relative to age control of specific classes of those nitrile type synthetic elastomers used in sealing devices which are resistant to petrol
8、eum base hydraulic fluids, lubricating oils, and aircraft fuels. This includes, but is not limited to, those nitrile (NBR or BUNA-N) elastomers previously covered by Section I of MIL-STD-1523. 1.1 Purpose: To provide users with appropriate references and information correlating past need and use of
9、age controls with current needs and to provide summary guidelines for consideration when future use of age controls is required or contemplated. SAE AIR1364 Revision A - 2 - 2. REFERENCES: 2.1 SAE Publications: Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001. AS1933A Age Contro
10、ls for Hose Containing Age-Sensitive Elastomeric Material 2.2 U.S. Government Publications: Available from DODSSP, Subscription Services Desk, Building 4D, 700 Robbins Avenue, Philadelphia, PA 19111-5094. MIL-STD-1523 2.3 Other Publications: ANA 438 3. BACKGROUND: 3.1 ANA Bulletin 438: After World W
11、ar II, particular concern was expressed relative to the apparent aging characteristics of the then recently developed BUNA-N and nitrile/neoprene blended elastomers being used in critical sealing devices of aircraft hydraulic, lubricating, and fuel systems. These early compounds apparently possessed
12、 poor ozone and weather resistance characteristics and were soon classified as age sensitive. As a result, age controls were established on these materials, initially in various general coverage government documents; when this proved unwieldy, all requirements were collected in 1958 and published in
13、 a single document, ANA Bulletin 438. Unfortunately, subsequent interpretations of this document by various agencies and contractors resulted in additions and variations in its implementation with subsequent confusion, abuses, and cost increases being incurred during enforcement of these variations.
14、 3.2 MIL-STD-1523: At the same time age controls leading to ANA 438 were being promulgated, at least ten programs were initiated relative to evaluation of long term aging of elastomeric materials. Results of these evaluations have been summarized in an excellent Air Force report AFMA-TR-67-235. The
15、tests indicated that, while certain mechanical properties did undergo some change with time (i.e., increases in hardness, tensile, and modulus with a corresponding decrease in ultimate elongation), these property changes tended to level off after 4 or 5 years. Further, the changes that did occur wer
16、e not of sufficient magnitude to result in seal failure. SAE AIR1364 Revision A - 3 - 3.2 (Continued): In addition to the above test programs, a large amount of performance data for old components containing over-age elastomeric seals has also been generated over the years that further indicate elas
17、tomers are less affected by aging than originally expected. Several of the more widely publicized studies involved the analysis of equipment removed from two aircraft that had crashed during WW II, one in the Libyan desert and the other on the Arctic ice cap. Functional tests performed on assemblies
18、 and mechanical property data on O-rings from these aircraft indicated that the elastomeric seals were in remarkably good condition when tested and that most of these old units functioned within their original specification limits. As the elastomeric parts removed from these two planes had probably
19、been cured in 1941 or 1942, these materials represented the state of the art for very early nitrile or nitrile-neoprene blended compounds. In view of the above results and the fact that overall properties of current nitrile materials are much improved over those evaluated, it was concluded that the
20、then current age controls should be reconsidered and made less restrictive. Accordingly, MIL-STD-1523 was promulgated and when released in 1973, superseded ANA Bulletin 438. Among other considerations, this document basically provides for a cure date limitation of twelve quarters from cure date to a
21、cceptance of the seals or bulk hose by the original procuring activity, whether a government agency, a first or second tier subcontractor or kitter. In all cases, continued use of cure dates is intended to provide for good first-in/first-out warehousing procedures. 3.3 MIL-STD-1523A: (R) MIL-STD-152
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