A study on friction and wear properties of PTFE coatings under vacuum conditions

The friction and wear properties of polytetrafluoroethylene (PTFE) coatings were studied in detail on a ball-on-disk wear tester under vacuum conditions. Experimental results showed that the friction coefficients of the PTFE coatings first increased with the increase of sliding velocity and then decreased with the increase of sliding velocity when the sliding velocity was higher than 1.2 m/s. The wear of the PTFE coating first decreased with the increase of sliding speed and then increased as the sliding speed increased. The friction coefficient decreased with the increase of load. The wear of PTFE coating first decreased with the increase of load and then increased with the increase of load when the load was higher than 6 N. The environmental pressure has insignificant effect on the friction coefficient of PTFE coating, and the friction coefficient of PTFE coating under air condition is slightly higher than that under vacuum condition. The wear first decreased with the increase of environmental pressure and then increased rapidly with the increase of environmental pressure when the pressure was higher than10 Pa. Scanning electron microscope (SEM) was utilized to investigate the worn surfaces, the self-lubricating films and debris.