Break-away friction of PTFE materials in lubricated conditions

This study investigates the tribological characteristics at initiation of sliding (break-away friction) of several polytetrafluoroethylene based materials. Four PTFE composites, pure PTFE, and white metal were tested in a reciprocating tribo-meter with the block on plate configuration against a steel counter-surface. Apparent contact pressure and oil temperature were varied from 1 to 8 MPa and 25 to 85 degrees C respectively. SEM investigations revealed wear patterns of the PTFE materials and the abrasive nature of hard fillers. Bronze filled, carbon filled, and pure PTFE were found to provide lower break-away friction and less variation over the course of testing and generally superior properties. (C) 2011 Elsevier Ltd. All rights reserved.