MSE 298 Seminar (MDEA): Atomistic Mechanisms of Friction for MoS2 and Beyond

Abstract: Molybdenum disulfide is a lamellar solid used to lower friction and wear in applications ranging from additives in specialty greases to coatings on components that operate in space. However, the tribological behavior of MoS2 is extremely sensitive to synthesis parameters, the environment, and operating conditions, which impedes accurate and consistent prediction of performance in lubricant or component design. One approach to understanding this very complex behavior is to break it down into a fundamental “unit” of tribology (i.e., sliding of a single asperity). Single asperity friction is studied using atomic force microscopy and matched molecular dynamics simulations. Here, we share examples of such studies of the atomistic origins of temperature, velocity, and orientation dependence of friction, as well as head-to-head comparisons between MoS2 and other 2D materials, including graphene, a graphene-MoS2 heterostructure, and other transition metal dichalcogenides. These studies suggest correlations between friction behavior at the single asperity scale and fundamental atomic features of the materials that can ultimately be the starting point to guide design with MoS2 and beyond.

Bio: Ashlie Martini is professor and chair of Mechanical Engineering at UC Merced. She obtained her B.S. and Ph.D. from Northwestern University. Professor Martini’s contributions to the field of tribology have been recognized by the ASME Burt L. Newkirk Award and the AFOSR Young Investigator Award, as well as multiple best paper and presentation awards. Professor Martini also recently became a fellow of the Society of Tribologists and Lubrication Engineers. In terms of teaching, she received the UC Merced campus-wide awards for Distinguished Undergraduate Teaching and Distinction in Graduate Teaching and Mentorship. Professor Martini’s service roles have included editor of the journal Tribology Letters, director of the Society of Tribologists and Lubrication Engineers, and chair of multiple international conferences.