Frictional figures of merit for single layered nanostructures

TL;DR

This study evaluates the frictional properties of layered nanostructures like graphane and MoS2, showing they can slide with minimal energy loss due to their low critical stiffness and charge repulsion, with WO2 being a promising superlubricant.

Contribution

The paper introduces ab-initio calculations of interlayer interactions and applies the Prandtl-Tomlinson model to identify conditions for nearly dissipationless sliding in layered nanostructures.

Findings

Layered nanostructures exhibit low critical stiffness under high load.

Intrinsic stiffness exceeds critical stiffness, preventing stick-slip behavior.

WO2 shows exceptional potential as a superlubricant.

Abstract

We determined frictional figures of merit for a pair of layered honeycomb nanostructures, such as graphane, fluorographene, MoS$_2$ and WO$_2$ moving over each other, by carrying out ab-initio calculations of interlayer interaction under constant loading force. Using Prandtl-Tomlinson model we derived critical stiffness required to avoid stick-slip behavior. We showed that these layered structures have low critical stiffness even under high loading forces due to their charged surfaces repelling each other. The intrinsic stiffness of these materials exceed critical stiffness and thereby avoid the stick-slip regime and attain nearly dissipationless continuous sliding. Remarkably, tungsten dioxide displays much better performance relative to others and heralds a potential superlubricant. The absence of mechanical instabilities leading to conservative lateral forces is also confirmed directly by the simulations of sliding layers.