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Use of VUV Radiation to Control Elastomer Seal AdhesionDue to their wide operating temperatures and low leakage rates, silicone elastomers are the only class of flight qualified elastomer materials that currently meet NASA's needs for various seal applications, which include docking and hatch seals for future space exploration vehicles. However, silicone elastomers are naturally sticky and exhibit sizeable adhesion when mated against metals and other silicone surfaces. This undesirable adhesion can make undocking spacecraft or opening a hatch problematic. Two approaches that can be used to reduce seal adhesion include use of grease or, application of low doses of atomic oxygen (AO). This paper investigates a third approach: the application of light doses of vacuum ultraviolet (VUV) radiation. Presented are the adhesion and leakage characteristics of S0383-70 silicone elastomer exposed to various VUV doses in the 115 to 200 nm wavelength range. The data indicate that adhesion is expected to be less than the target threshold maximum of 2 lb/in(exp2) after about 1 J/cm(exp2) of VUV exposure for seal-to-metal configurations and after 2 J/cm(exp2) for seal-to-seal configurations with no significant damage, or increase in seal leakage. This paper shows that VUV, without AO or grease, can be an effective means to reduce adhesion to the desired levels necessary for space seals with minimal change in seal leak rates.
Document ID
20140002504
Document Type
Technical Memorandum (TM)
Authors
deGroh, Henry C., III (NASA Glenn Research Center Cleveland, OH, United States)
Puleo, Bernadette J. (NASA Glenn Research Center Cleveland, OH, United States)
Waters, Deborah L. (NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
March 31, 2014
Publication Date
September 1, 2013
Subject Category
Mechanical Engineering
Report/Patent Number
E-18743
NASA/TM-2013-218067
AIAA Paper 2013-3915
Meeting Information
AIAA Propulsion and Energy Event(San Jose, CA)
Funding Number(s)
WBS: WBS 871056.06.02.01.09.02
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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