In this research, we aimed to explore the mechanism of carbon filled PTFE forming a carbon film on the sliding surface and reducing the friction. We evaluated the influence of water content on friction behavior using a pin-on-disk tester, and examined the mechanism by surface analysis. Pitch type carbon filled PTFE showed stable and lower friction than PAN type carbon filled PTFE. It was found that there is a difference in the influence of moisture between PAN type carbon filled PTFE and Pitch type carbon filled PTFE, and that effect is small in Pitch type carbon filled PTFE.
