Friction testing Combined With Online Monitoring
of Residual Gas
The perfluoropolyethers (PFPE) are a class of fluids that are likely used as lubricants for space mechanisms. It is reported that their performance in the presence of tribological conditions and in the presence of various catalytic materials has caused serious deficiencies. In many cases, the PFPE fluids were extensively degraded and caused severe corrosion problems on metal surfaces.
One explanation for the observed degradation is that the friction process removes the protective native oxide from the metal surface and allows the fluid to contact the atomically clean steel. A degradation reaction leads to cracking of the organic PFPE and formation of metal fluorides. These fluorides, in turn, attack the PFPE fluid much faster than does the clean metal itself.
Tests have been made to answer the following questions:
Do chemical reactions stop immediately after the tribological test is stopped, or is the process autocatalytic going on?
Can a correlation in the residual gas analysis and the quality of the tribological contact be found?