Paper NS+TR-TuM2
Tribological Behavior of Nanostructured Materials Predicted from Molecular Dynamics Simulations

Tuesday, November 10, 2009, 8:20 am, Room L

Nanostructured materials such as fullerenes and nanotubes have been of much interest to tribologists since the discovery of C₆₀, buckminsterfullerene, in 1985. Characterized by weak van der Waals (vdW) forces that govern the interactions between these nanostructured materials, low friction coefficients are obtained through combinations of rolling, sliding, and rotating at the sliding interface. This presentation will report on the tribological properties of onion-like carbon (OLC) fullerenes with and without a residual diamond core as a solid lubricant between two sliding, diamond-like carbon (DLC) surfaces. The molecular dynamics (MD) simulations presented here utilize the reactive empirical bond order (REBO) potential for short range interaction coupled with the Lennard-Jones (LJ) potential for long range vdW interactions Within these simulations no discernable difference is predicted between the OLC fullerenes with a diamond core and those without. Further, the frictional behavior of these systems is highly dependent on the interactions that take place between the fullerenes and the DLC substrates. Without the formation of bonds with the substrates, the OLC fullerenes in the simulations are able to roll providing extremely low frictional forces, but as bonds begin to form, the OLC fullerenes begin to slide which causes a significant increase in the observed friction. The presentation will also report on the mechanical properties of molybdenum disulfide (MoS₂) nanotubes and their response when used as solid lubricants between two sliding Mo surfaces. Variations in number of nanotube layers, temperature, and compressive load are examined in order to characterize each system. The authors acknowledge the support of the National Science Foundation Grant No. CMMI-0742580.