Coatings for Fuel Cell Propulsion Compressor Bearings

Fuel cell air handling systems require clean and contaminant-free inlet air, which dictates that oil-free, motorized, compressor/expander systems should be used. Although there is no sliding contact in the steady state operation of the foil bearing, occasional contact between the foil and journal surfaces at startup and shutdown and during overload situations, could limit the bearing life. Therefore, to ensure that the compressor system is highly efficient and reliable the foil air bearings need wear resistant, low friction coatings. The objective of the proposed STTR investigation is to identify new coatings for use in fuel cell propulsion compressor bearings that would allow the foil bearing to be functional from low temperature start-up conditions to the maximum temperatures encountered during operation. The proposed program will build on a novel hydrogenated diamond like carbon (DLC) coating developed at the Argonne National Laboratory (ANL). The goal of this joint MiTiREG and ANL STTR Phase I program is to demonstrate the feasibility of ANL hydrogenated DLC and MiTiREG KorolonTM coating technology for fuel cell propulsion compressor bearings. This will be accomplished through coating adhesion and tribological testing of the coatings against various potential shaft coatings such as the NASA developed PS304 and/or Korolon 1350B.