Investigation of PTFE Tribological Properties Using Molecular Dynamics Simulation

Abstract

Polytetrafluoroethylene (PTFE) has been widely applied in industrial engineering applications. Its tribological behaviors are extensively studied using the experimental method. However, the friction and wear mechanisms of PTFE still need to be investigated from a microscopic point of view. In this study, we established a two-layer PTFE frictional model to simulate the frictional behaviors of PTFE using molecular dynamics (MD) simulation and verified it by experiments. To directly compare the MD simulation results to the experimental results, the motion form, range of the external load, relative velocity, and environmental temperature matched each other as closely as possible. We found that the increment of normal force is faster than that of the friction force with an increase in the external load applied to the upper layer, resulting in an apparent decrease in the friction coefficient and an increase in wear depth. The smaller PTFE fragments correspond to a higher contact temperature for a fixed external load. The higher contact temperature induced a higher mobility increasing the friction force, thereby enhancing the friction coefficient. However, the influence of PTFE fragments on the friction coefficient is unremarkable compared to the external load.