Properties of Perfluoropolyethers for Space Applications

The perfluoropolyether (PEPE) class of liquid lubricants has been used for space applications for over two decades. At first, these fluids performed satisfactorily, as early spacecraft placed few demands on their performance. However, as other spacecraft components have become more reliable and lifetimes have been extended, PEPE lubricant deficiencies have been exposed. Therefore, the objective of this paper is to review the PEPE properties that are important for successful long term operation in space.