Fomblin Z25: A new method for its degradation assessment & proposal for safe operation in space

Abstract

We present an overview of the studies of the past two years performed by the Mechanisms Section of the European Space Research and Technology Centre (ESA-ESTEC), the European Space Tribology Laboratory (ESTL) and Aerospace & Advanced Composites GmbH (AAC) on the tribological and chemical degradation mechanisms of PFPE oil Fomblin
Z25.
Tests have been performed using a spiral orbit tribometer (SOT), demonstrating the susceptibility of the lifetime of this lubricant to a range of variables (including load and temperature). A residual gas analyser was implemented, demonstrating a technique for detecting the failure of a PFPE lubricant independent of the friction coefficient through in-situ monitoring of
selected volatile gases throughout the tests. To the authors knowledge this work is the first demonstration of the failure of Fomblin Z25 oil independent from friction, torque, or motor current increase.
In addition, SOT and pin-on-disc (POD) research efforts have been aimed at identifying the so called autocatalytic
effect during lubricant degradation.