This study reports on the tribological performance of aromatic thermosetting co-polyester (ATSP) and polyether ether ketone (PEEK)-based polymer composite coatings mixed with PTFE filler. The coatings were tested across a wide temperature range from −180 to 110 ℃ to simulate the environmental temperatures on Titan, Moon, and Mars, which are of particular interest for NASA’s future exploratory missions. An experimental setup was developed to conduct the pin-on-disk experiments under dry sliding conditions and extreme temperature and contact pressure. Transfer film formation and its characteristics were found to play significant roles in the tribological performance, and the characteristics of the film were temperature-dependent. The XPS and SEM analysis indicated the increase of the PTFE content in the transfer film as the temperature decreased to cryogenic conditions. The coefficient of friction did not follow a linear trend with temperature and was minimum at 110 ℃ and maximum at −180 ℃. ATSP coating showed superior performance with lower friction and unmeasurable wear at all temperatures, whereas PEEK coating exhibited maximum wear at 25 ℃ followed by −180, and 110 ℃.

Numerous tribological applications, wherein the use of liquid lubricants is infeasible, require adequate dry lubrication. Despite the use of polymers as an effective solution for dry sliding tribological applications, their poor wear resistance prevents the utilization in harsh industrial environment. Different methods are typically implemented to tackle the poor wear performance of polymers, however sacrificing some of their mechanical/tribological properties. Herein, we discussed the introduction of a novel additive, namely microencapsulated phase change material (MPCM) into an advanced polymeric coating. Specifically, paraffin was encapsulated into melamine-based resin, and the capsules were dispersed in an aromatic thermosetting co-polyester (ATSP) coating. We found that the MPCM-filled composite exhibited a unique tribological behavior, manifested as "zero wear", and a super-low coefficient of friction (COF) of 0.05. The developed composite outperformed the state-of-the-art polytetrafluoroethylene (PTFE)-filled coatings, under the experimental conditions examined herein.

High-performance polymers (HPPs) are increasingly used in different industrial machinery components, particularly for rubbing parts that demand reliable and durable operation at extreme sliding conditions such as elevated temperature environments, where the use of conventional lubricants is not feasible. The current study investigates the role of environmental temperature on the tribological properties of three advanced HPPs, namely aromatic thermosetting copolyester (ATSP), polyimide (PI), and polyether ether ketone (PEEK) based polymer composites. Tribological experiments were carried out at different environmental temperatures from room temperature up to 300 °C, and under dry sliding conditions. Specific attention was given to the role of temperature on the development of transfer films and its subsequent effect on the tribological performance. The ATSP composite was recommended as the best performing material, based on the overall tribological performance at all examined operating temperatures.