Improved Additives for Perfluoropolyalkylether (PFPAE) Lubricants with Silicon Nitride Rolling Elements

Hybrid bearings utilizing silicon nitride rolling elements in conjunction with steel inner and outer bearing races are being developed for use in gas turbine engines. Due to their outstanding thermal and oxidative stability, perfluoropolyalkylether (PFPAE) fluids are of interest as potential high temperature liquid lubricants in these systems. However, this same unique chemistry that provides their higher stabilities also creates some potential problems. One of these is the lack of compatibility with silicon nitride rolling elements. Under the Phase I program, METSS investigated a series of promising, new, soluble additives for PFPAE fluids that demonstrated significant improvement in compatibility with silicon nitride bearing materials under tribological stress conditions and high temperature exposures. Under the proposed Phase II program. METSS will build upon the knowledge gained from the Phase I program to develop a new improved class of PFPAE lubricants optimized for compatibility with hybrid bearing materials. The proposed program will also address additional issues related to material compatibility issues, personnel safety, environmental impact and use costs. The Phase II efforts will clearly define and support a viable path for technology commercialization and field implementation.