Air Cycle Machine Low Friction, Medium Temperature, Foil Bearing Coating

The purpose of this project is to demonstrate the feasibility of using an innovative, durable, low friction, and non-toxic solid lubricant coating for foil air bearings for air cycle machines (ACM). Acrees coating provides superior wear characteristics at all temperatures and provides a substantial improvement over polyimide type coatings that are currently used on ACMs. The coating consists of two parts: A coating on the journal and a separate coating on the foil. The journal coating is a proven, highly lubricious, extremely robust, self-lubricating nanocomposite material that reduces frictional heating and is resistant to scuffing and brittle fracture over a wide temperature range (>650 C). The coating consists of an innovative graded nanocomposite structure with a soft noble-metal matrix intermixed with nanoparticles of a hard transition metal nitride. The top foil will be coated with a proven solid lubricant coating of aluminum-bronze (Cu-4Al) alloy. The coatings will be applied using Acrees Energetic Deposition Process which yields a highly dense and smooth film that does not require post-deposition grinding or polishing. The combination of the nanocomposite journal and aluminum-bronze foil coatings results in an extremely robust, wear resistant, and highly reliable air bearing surface that will significantly outperform todays polyimide coatings.