SBIR-STTR Award

This proposal addresses subtopic S4.04 Extreme Environments Technology and specifically the listed interest in long life bearings, tribological surfaces, and lubricants. NASA is interested in expanding its ability to explore deep atmosphere and surface of giant planets, moon surfaces, asteroids, and comets through use of long-lived (days or weeks) balloons and landers. Dragonfly will launch in 2026 and arrive in 2034 on Titan. Mars sample return is a proposed mission to return samples from surface of Mars to Earth. The Artemis program will land the first woman and next man on Moon by 2024. Conceptual landing probes for Europa have been proposed. However, the missions would experience extreme conditions: temperatures ranging from -220°C on Europa, -200 °C on Ganymede to -180°C on Titan. In addition, the instrument will go through high cosmic radiation environments with long duration of the mission. At these extreme conditions, traditional oil lubricants and greases are infeasible, resulting in dry sliding conditions with significant detrimental effects on component performance. The reliable operation of moving parts and tribological components (e.g., bearings, gears, sealings, etc.) in the cryogenic environment is a key for successful accomplishment of future NASA missions. Therefore, selection and design of new lubrication and protection are imperative for each application. Tribological experiments are therefore necessary to simulate relevant environments to mitigate mission risk. This proposal offers a unique solution: aromatic thermosetting copolyester (ATSP) coating on ATSP coating sliding is shown to have low coefficient of friction (COF) and “zero wear” from -196°C to 300°C. This excellent tribological performance leads us to introduce ATSP-based coatings for Europa cryogenic environment conditions. we will investigate the tribological performance of ATSP-based composites using flat pin-on-disk experiments under conditions in combination with radiation effect. Potential NASA Applications (Limit 1500 characters, approximately 150 words): ATSP-based tribological products have wide temperature range (-196 to 300°C) with low wear and friction and have applicability for devices used in future missions to Titan, Europa, the Moon, and Mars. Addressable missions include the Dragonfly mission, mechanical components in observatory platforms, Mars sample return, and lunar terrain vehicles. The reliable operation of moving parts and tribological components (e.g., bearings, gears, sealings, etc.) in such extreme environments is key for successful accomplishment of future NASA missions. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words): ATSP-based tribological products are applicable for Aerospace, Automotive, Space Exploration, and Energy. The tribo-pair concept developed in Phase I potentially offers world leading reduction in friction and wear across a very broad range of temperatures. Reductions in COF and wear enable more stable performance and longer lifetimes - providing an attractive option for many device conditions. Duration: 6

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 ?m 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. Anticipated

Benefits:
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. 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.