An unbranched perfluoropolyether is the current ball bearing lubricant for deep space flight. We report measurements of viscosity to moderate pressures for the calculation of pressure-viscosity coefficients to temperatures as low as −40°C. A free volume model predicts that a minimum pressure-viscosity coefficient exists at higher temperature. The existence of a minimum αoT is confirmed by viscometry at temperatures to 180°C.

Issue Section:
Technical Papers
Keywords:
mechanical contact, tribology, viscosity, lubrication, rheology, shear strength, polymers, sliding friction
Topics:
Pressure, Temperature, Viscosity
1.
Jones
, Jr.,
W. R.
,
1995
, “
Properties of Perfluoropolyethers for Space Applications
,”
STLE Tribol. Trans.
,
38
, p.
3
3
.
2.
Blok, H., 1963, “Inverse Problems in Hydrodynamic Lubrication and Design Directives for Lubricated Flexible Surfaces,” Proceedings of the International Symposium on Lubrication and Wear, McCutchan Publishing Corporation, Berkeley, CA, p. 66.
3.
Bair
,
S.
,
1993
, “
An Experimental Verification of the Significance of the Reciprocal Asymptotic Isoviscous Pressure
,”
ASLE Tribol. Trans.
,
36
, No.
2
, pp.
154
–
155
.
4.
Yasutomi
,
S.
,
Bair
,
S.
, and
Winer
,
W. O.
,
1984
, “
An Application of a Free Volume Model to Lubricant Rheology 1-Dependence on Temperature and Pressure
,”
ASME J. Tribol.
,
106
, No.
2
, pp.
291
–
302
.
5.
Cook
,
R. L.
,
Herbst
,
C. A.
, and
King
,
H. E.
,
1993
, “
High-Pressure Viscosity of Glass-Forming Liquids Measured by the Centrifugal Force Diamond Anvil Cell Viscometer
,”
J. Phys. Chem.
,
97
, No.
10
, p.
2359
2359
.
6.
Krytox Technical Bulletin No. L5, E.I. Dupont De Nemours and Company, Wilmington, DE, p. 4
7.
Bair
,
S.
,
Khonsari
,
M.
, and
Winer
,
W. O.
,
1998
, “
High-Pressure Rheology of Lubricants and Limitations of the Reynolds Equation
,”
Tribol. Int.
,
31
, No.
10
, p.
582
582
.
8.
Corti
,
C.
, and
Savelli
,
P.
,
1993
, “
Synthetics Profile: Perfluoropolyether Lubricants
,”
Journal of Synthetic Lubrication
,
9
, No.
4
, pp.
311
–
330
.
Copyright © 2001
 by ASME
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