AVS 58th Annual International Symposium and Exhibition
    Tribology Focus Topic Thursday Sessions
       Session TR+AS+SS-ThM

Paper TR+AS+SS-ThM10
Lubrication Mechanisms of MoS2 Fullerene-Like Nanoparticles: Coupling Computer and Experimental Works

Thursday, November 3, 2011, 11:00 am, Room 111

Session: Atomic-scale Characterization of Tribological Interfaces
Presenter: Eric Bucholz, University of Florida
Authors: E.W. Bucholz, University of Florida
I. Lahouij, Ecole Centrale de Lyon, France
F. Dassenoy, Ecole Centrale de Lyon, France
S.B. Sinnott, University of Florida
J.M. Martin, Ecole Centrale de Lyon, France
Correspondent: Click to Email
Inorganic fullerene (IF)-like MoS2 nanoparticles have been shown to be good lubricating and anti-wear additives when dispersed in a base oil. This improved tribological performance appears to be a result of the size and structure of the nanoparticles along with the test conditions. Possible lubrication mechanisms include pure rolling to sliding to the exfoliation of lamellar MoS2 sheets inside the contact. In situ transmission electron microscopy (TEM) experiments have been used to manipulate individual MoS2 nanoparticles and investigate their responses to compression and friction under different conditions. However, the very small scale of the MoS­2 nanoparticles makes distinguishing the properties which affect the lubrication mechanism exceedingly difficult; thus, a computational approach is used to more fully understand the most important mechanisms. Therefore, classical molecular dynamics (MD) simulations of individual nested MoS2 nanoparticles are performed where they are subjected to compression and shear forces between sulfur-terminated molybdenum surfaces. Two specific nanoparticle configurations are considered, with both structures containing three layers. The first configuration is a curved, ellipsoidal MoS2 nanoparticle structure with a major and minor diameter of approximately 8.9 and 6.6nm, respectively. The second nanoparticle configuration is an octahedron with grain boundaries that are approximately 6.2 nm in length. MD simulations of these structures indicate the role of curved and faceted morphologies as well as grain boundaries on the rolling/sliding behavior and nanosheet exfoliation of the particles. The results are used to interpret the experimental TEM findings and predict the dominant mechanisms associated with enhanced lubrication through the addition of these particles to base oils. This work is supported by the Office of Naval Research .