The role of strain induced tribochemistry at nanoscale in reducing wear/friction at macroscale

Diana Berman1, Kalyan Mutyala1, Badri Narayanan2, Srilok Srinivasan1, Subramanian Sankaranarayanan1, Ali Erdemir3, and Anirudha V. Sumant1*

1Center for Nanoscale Materials, 9700 S. Cass Ave, Argonne National Laboratory, Argonne, IL, 60439

2Materials Science Division, 9700 S. Cass Ave, Argonne National Laboratory, Argonne, IL, 60439

3Energy Systems Division, 9700 S. Cass Ave, Argonne National Laboratory, Argonne, IL, 60439

Abstract

The mechanical energy dissipation between two sliding objects leads to friction and wear. However, its origin stems from the nanoscale interactions of multi-asperities at the sliding interface and critically depends on interacting materials and surrounding environment. This sliding interface is very dynamic in nature and difficult to probe directly to understand mechanism at play that is responsible for friction and wear. Our research efforts have been primarily focused on understanding atomic scale origin of the friction at the tribological interface and whether we can manipulate these interactions at atomic/molecular level that could results in affecting wear/friction behavior of the system at macroscale. In our recent efforts, we show a unique tribochemical route involving various 2D materials in combination with nanodiamonds or metallic nanoparticles that undergo an interesting materials transformation at the tribological interface during sliding process leading to the formation of onion like carbon (OLC) in the wear track resulting in near zero friction (superlubricity) and negligible wear. We systematically study evolution of tribochemical changes occurring within a wear track using multifunctional tribometer integrated with Raman spectroscopy and 3D confocal  microscopy as well evaluate debris collected from the wear track using transmission electron microscopy. Combining that with the reactive molecular dynamics simulation studies we elucidate the mechanism of friction and show possible pathways to manipulate friction at nanoscale that can directly influence friction at macroscale. The implications of this discovery are profound and already demonstrating its potential in some commercial applications that we are exploring.