Thin solid lubricant films in space

Abstract

Solid lubricant films of thickness one micrometre or less are to an increasing extent being employed in spacecraft applications. This is particularly so where conditions dictate the use of solid lubricants (as opposed to fluids) and where the component to be lubricated is of a precision that precludes the use of thick films. A further advantage is that the thinness of such lubricants actually promotes low friction when the substrates involved are of high hardness. This paper reviews the tribological properties of thin, solid film lubricants as determined in vacua typical of those encountered in spacecraft environments. Further, it attempts to describe or predict (where no data exist) the performance of such films under specific spacecraft conditions whose effects on thin, solid film lubricants have, until recently, been unknown to the space tribologist. Such conditions include in vacuo cryogenic environments of spaceborne infrared telescope mechanisms and high flux, atomic oxygen environments of low earth orbits.