High performance polymer for dust tolerant extreme environment bearings

In Phase I, we demonstrated ATSP-based coatings vs. ATSP-based coatings have excellent tribological performance: low coefficient of friction (COF) and “zero wear” in a widet emperature application range (from -196°C to 300°C). Additionally, for ATSP-based coatings, the 50-year equivalent low-earth-orbit proton exposure had no effect on its tribological performance. This excellent tribological performance leads us to introduce ATSP coatings for Lunars’ dusty abrasive conditions in combination with wide temperature changes. In Phase II, the ATSP composite coatings were compared with one of the state of the art (SOA) material, polyether ether ketone (PEEK) based polymer composite coatings for abrasive wear. The polymer-on-polymer system resulted in a significant reduction in friction up to 70%. The wear mechanism was a mixed mode of two-body and three-body abrasion for metal-on-metal and metal-on-polymer tribopairs, while the polymer-on-polymer tribopair significantly mitigated the sand and dust accumulation at the interface with three-body abrasion as the dominant wear. Both polymer composites showed similar frictional behavior, while ATSP composite showed superior abrasive wear resistance, particularly under small size dust (<38 μm size) environment. ATSP coating showed higher resistance to abrasive wear than PEEK, and dust was more detrimental to tribological performance (i.e., friction and wear), particularly for PEEK coating. The Phase II Sequential proposal will utilize these capabilities and advance the TRL 3-4 to TRL 6-7 and a pathway to TRL 9. In addition to the rolling-sliding simulated test for bearing application, full scale bearings will be fabricated and tested in the simulated conditions and also will be tested using Harmonic drive, which is one the most important parts for the lunar rovers for actuation. At the end of Phase II-S, custom fabricated ATSP bearing will be handed over to NASA.
Benefits: Potential NASA Applications We foresee several applications relevant for NASA's planned and future mission needs: 1. The dust tolerant bearings can be used in any lunar application where the challenge of dust is there. 2. The improved dust tolerant bearings can be also an option for Mars missions. 3. ATSP composite seals can increase the wear life expectancy for any dynamic or slow moving seals. 4. ATSP composite seals can be used as high pressure static seals in wide range of temperature variations. Potential Non-NASA Applications A broad spectrum of users in the energy and industrial sectors may benefit from these advances towards part lifetime and reliability: 1. ATSP bearing composite for precision liquid transfer and high-pressure fluid sealing applications: wear rings, components in the compressors, valves, pumps. 2. Hydrodynamic tilting pad bearing applications to extend the service life and reduce maintenance cost.