High Temperature Solid Lubricant Coatings for Air Foil Bearings

The objective of this program is to develop a robust foil bearing system suitable for application to the Liberty Works high mach engines for RATTLRS and BLACKSWIFT.  An integral objective is to identify and verify a foil bearing coating system that can demonstrate stable operation at 50 lbs load and 25 m/sec surface speeds for several minutes during start up and before the hydrodynamic air film is formed. Several existing coatings will be tested and compared to MiTis Korolon, which has demonstrated successful operation at shut down conditions and after thermal cycling to 1500oF in an air environment.  Another objective of this effort is to demonstrate the integrated bearing and coating system robustness.   The specific objectives of this Phase I program are to 1) Establish the bearing and coating system requirements; 2) select the candidate materials, fabricate test components for testing and prepare the test rigs; 3) conduct screening testing to evaluate candidate coating systems; 4) review the test data and select materials systems for testing under Phase II; 5) prepare the conceptual design of the Phase II simulator of the Liberty Works High Mach engine and 6) prepare the final report including detailing the Phase II program plans.   BENEFIT: This effort will increase the technology readiness level for compliant foil bearings so that they may be applied in the emerging High Mach gas turbine engines and subsequently end users in both the military and commercial sectors.  Given the very specific end item application the first military application is expected in the systems such as RATTLRS and Blackswift.  Once proven, many DOD and commercial legacy gas turbine engines will benefit.  The most likely initial application of the advanced coating will be in seals, providing a substantial retrofit market for improved engine efficiency and durability.  Other commercial applications include natural gas pipeline compressors, hydrogen gas compressors for transportation and delivery and many of the micro-gas turbines used for combined heat and power.  By collaborating with engine contractors, the information gleaned from this program will support and enhance the marketability of foil bearings and seals for wide ranging applications including Integrated Power Units, gas turbine engines for use in UAVs, missiles, drones, helicopters and General Aviation aircraft, as well as turbo-expanders, turbochargers, industrial compressors/blowers, natural gas pipeline compressors and other energy producing oil-free turbomachinery.