Foil air bearings are self-acting h

Foil air bearings are self-acting hydrodynamic bearings which rely upon solid lubricants to reducefriction and minimize wear during sliding which occurs at start-up and shut-down when surface speedsare too low to allow the formation of a hydrodynamic air film. This solid lubrication is typicallyaccomplished by coating the non-moving foil surface with a thin, soft polymeric film. The followingpaper introduces a systems approach in which the solid lubrication is provided by a combination of selflubricating shaft coatings coupled with various wear resistant and lubricating foil coatings. The use ofmultiple materials, each providing different functions is modeled after oil-lubricated hydrodynamic sleevebearing technology which utilizes various coatings and surface treatments in conjunction with oillubricants to achieve optimum performance.In this study, room temperature load capacity tests are performed on journal foil air bearingsoperating at 14,000 rpm. Different shaft and foil coating technologies such as plasma sprayed composites,ceramic, polymer and inorganic lubricant coatings are evaluated as foil bearing lubricants. The resultsindicate that bearing performance is improved through the individual use of the lubricants and treatmentstested. Further, combining several solid lubricants together yielded synergistically better results than anymaterial alone.