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Relative Lifetimes of Several Space Liquid Lubricants Using a Vacuum Spiral Orbit Tribometer (SOT)A vacuum spiral orbit rolling contact tribometer (SOT) was used to determine the relative lifetimes of several unformulated space liquid lubricants. The lubricants tested included a synthetic hydrocarbon (Pennzane 2001 A), three perfluoropolyethers (Krytox 143AC, Fomblin Z25, and Brayco 815Z), three silahydrocarbons (a tri, a tetra, and a penta) and a polyalphaolefin (Nye PAO-100). The SOT simulates the ball motions in an angular contact bearing and tribochemically degrades microgram quantities of lubricant. Test failure is determined when a preset friction coefficient is exceeded. Relative lifetime (orbits/micro-g) is defined as the number of ball orbits to failure divided by the amount of lubricant on the ball. Conditions included 10 to 200 rpm rotational speed, approximately 50 micro-g lubricant, an initial vacuum < 1.3x10(exp -6) Pa, room temperature (approximately 23 C), a mean Hertzian stress of 1.5 GPa, and 440 C stainless steel specimens. Lubricated lifetimes from longest to shortest were Pennzane 2001 A, the silahydrocarbons and the PAO-100, 143AC, ZI-5, and then 815Z. Relative lifetimes compare favorably to full-scale vacuum gimbal bearing tests. The effect of varying the mean Hertzian stress on the lifetime of some of the lubricants was examined.
Document ID
20010069634
Acquisition Source
Glenn Research Center
Document Type
Preprint (Draft being sent to journal)
Authors
Jansen, Mark J. (AYT Corp. Brook Park, OH United States)
Jones, William R., Jr. (NASA Glenn Research Center Cleveland, OH United States)
Predmore, Roamer E. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Loewenthal, Stuart L. (Lockheed Martin Missiles and Space Sunnyvale, CA United States)
Date Acquired
September 7, 2013
Publication Date
June 1, 2001
Subject Category
Nonmetallic Materials
Report/Patent Number
E-12819
NASA/TM-2001-210966
NAS 1.15:210966
Meeting Information
Meeting: 2nd World Tribology Congress
Location: Vienna
Country: Australia
Start Date: September 3, 2001
End Date: September 7, 2001
Sponsors: International Tribology Council, Austrian Tribology Society
Funding Number(s)
PROJECT: RTOP 274-00-00
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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