Tribology is the study of friction and wear at interacting surfaces. The impact of these forces on the global economy is directly related to energy loss in systems and how that energy may be recovered to reduce fuel consumption. Holmberg, K. et al. (Friction 2017 5, 263-264) indicated that utilizing new surfaces, materials and lubrication technologies for friction reduction and wear protection in vehicles and other machinery worldwide could realize a long-term savings of 1.4 percent of annual GDP and 8.7 percent of total energy consumption. Two-dimensional (2-D) materials have been an integral part of material technologies used to control friction and wear in applications. Molybdenum disulfide (MoS2) is a transition metal dichalcogenide that is useful in solid lubrication, heterostructures, catalysis and 2-D-based electronic devices, while graphene is a one-atom-thick, 2-D material of carbon atoms in a hexagonal lattice. The lamellar structure of MoS2 is similar to that of graphene, mica and hexagonal boron nitride, with weak interactions between the lamella leading to exceptional frictional properties. This makes it necessary to understand interactions at the atomic scale. Uncovering the physics of atomic-scale friction and its influence on energetics while strained is of value in a fundamental understanding. We investigate the change in reactivity induced by local surface strain and applied loads. This will give insight into properties such as reduction and oxidation potentials. As a 2-D material is deformed, changes in the local bond-order should render specific locations more susceptible to tribochemical reactions. The nature of tribochemical reactions is still vague, therefore we used atomistic simulation to construct models that accurately predict results from tribological experiments. Establishing relationships between the properties of 2-D materials and frictional performance aids in developing more robust experimental studies and helps to better understand friction, wear and lubrication.
Texas A&M University
Predicting Tribochemically Induced Reactions of Two-Dimensional Materials
Area of Study