400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (724) 776-4841 Fax: (724) 776-0790 Web: www.sae.org SAE TECHNICAL PAPER SERIES 2008-01-1619 Compatibility Study of Fluorinated Elastomers in Automatic Transmission Fluids Nancy Zeng General Motors Corporation 2008 SAE Internati onal Powertrains, Fuels and Lubricants Congress Shanghai, China June 23-25, 2008Downloaded from SAE International by University of Edinburgh, Thursday, August 09, 2018By mandate of the Engineering Meetings Board, this paper has been approved for SAE publication upon completion of a peer review process by a minimum of three (3) industry experts under th e supervision of the session organizer. All rights reserved. No part of this publication ma y be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electroni c, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. For permission and licen sing requests contact: SAE Permissions 400 Commonwealth DriveWarrendale, PA 15096-0001-USAEmail: [email protected]: 724-772-4028Fax: 724-776-3036 For multiple print copies contact: SAE Customer ServiceTel: 877-606-7323 (in side USA and Canada) Tel: 724-776-4970 (outside USA)Fax: 724-776-0790Email: [email protected] ISSN 0148-7191Copyright © 2008 GM Global Technology Operations, Inc. Published by SAE International with permission Positions and opinions advanced in th is paper are those of the autho r(s) and not necessarily those of SAE. The author is solely respo nsible for the content of the paper. A process is available by which discussions will be printed with the paper if it is published in SAE Transactions. Persons wishing to submit pape rs to be considered for presentation or publication by SAE should send the manuscript or a 300 word abstract of a proposed ma nuscript to: Secretary, Eng ineering Meetings Board, SAE. Printed in USADownloaded from SAE International by University of Edinburgh, Thursday, August 09, 20181ABSTRACT A compatibility study was conducted on fluorinated elastomers (FKM and FEPM) in various Automatic Transmission Fluids (ATF). Representative compounds from various FKM families were tested by three major FKM raw material producers – DuPont Performance Elastomers (DPE), Dyneon and Solvay. All involved FKM compounds were tested in a newly released fluid (ATF-A) side-by-side with conventional transmission fluids, at 150°C for various time intervals per ASTM D471. In order to evaluate the fluid compatibility limits, some FKM’s were tested as long as 3024 hrs, which is beyond the normal service life of seals. Tensile strength and elongation were monitored as a function of ATF exposure time. The traditional dipolymers and terpolymers showed poor resistance to the new fluid (ATF-A). Both types demonstrated significant decrease s in strength and elongation after extended fluid exposure at 150°C. Both dipolymers (Type 1) and terpolymers (Type 2) have been successfully used for transmission sealing applications in conventional transmission fluid (ATF-B). Terpolymers (Type 2) behaved slightly better than dipolymers (Type 1). All base resistance fluoroelastomers (Type 4, 5, and FEPM) and the low temperature flexible FKM grade (Type 3) demonstrated excellent fluid resistance in ATF-A. Another deterioration of the traditional dipolymers or terpolymers was eviden ced with surface cracking. Cracking displayed a temperature and time dependence. A 180° looping test and a mandrel bend flexibility test were used to evaluate the tendency of surface cracking. The tests were performed on specimens after being exposed to ATF’s at three temperatures to evaluate the impact of temperature and fluid. The bend test differentiated the aggressiveness of conventional transmission fluid (ATF-B) and new fluid (ATF-A), using the past history of successful performance (no cracking) of FKM Type 1 bisphenol-AF cured in conventional