| AVS 56th International Symposium & Exhibition | |
| Tribology Focus Topic | Tuesday Sessions |
| Session TR+SS-TuA |
| Session: | Surface Science for Tribology |
| Presenter: | S.B. Sinnott, University of Florida |
| Authors: | P. Barry, University of Florida P. Chiu, University of Florida S.R. Phillpot, University of Florida S.B. Sinnott, University of Florida |
| Correspondent: | Click to Email |
We report on the effect of small, fluorocarbon molecules on self-mated, aligned polytetrafluoroethylene (PTFE)-PTFE tribology using atomistic molecular dynamics simulations. Three fluorocarbon molecular classes were considered: C2F6, C4F10 and C8F18 with the amount of lubricant between the classes kept constant. Further, the effects of a relatively thin lubricating layer and a relatively thick lubricating layer were compared. The simulations predicted that the systems with thicker lubricating layers exhibited a friction coefficient that was significantly lower than those a thinner lubricating layer. Correspondingly, substantially more molecular wear of the PTFE surfaces were predicted for the latter systems. Interestingly, unlubricated PTFE-PTFE self-mated systems demonstrated low friction coefficients and molecular wear when the chains were slid in a direction parallel to the chain alignment, and unlubricated, aligned polyethylene (PE)-PE systems exhibited comparable or lower friction coefficients. The simulations further predicted that unlubricated, aligned PE-PTFE systems had friction coefficient values in between those of the PE-PE systems and PTFE-PTFE systems in which the chains slid in directions that were perpendicular to the alignment of the chains. Surprisingly, the highest friction coefficients in the PE-PTFE system occurred when the chains were slid in a direction parallel to the direction in which the chains were aligned. This result was attributed to the incommensurate nature of the sliding interface between the two different polymers. This work was carried out under the support of an AFOSR MURI.