Observation of normal-force-independent superlubricity in mesoscopic graphite contacts

TL;DR

This study demonstrates that in incommensurate graphite contacts, superlubricity with near-zero friction remains unaffected by normal loads up to 1.67 MPa, highlighting potential for practical low-friction applications.

Contribution

First experimental observation of normal-force-independent superlubricity in mesoscopic graphite contacts under ambient conditions.

Findings

Friction coefficients are essentially zero.

Superlubricity is robust against normal load.

Load-independent superlubricity observed up to 1.67 MPa.

Abstract

We investigate the dependence of friction forces on normal load in incommensurate micrometer size contacts between atomically smooth single-crystal graphite surfaces under ambient conditions. Our experimental results show that these contacts exhibit superlubricity (super-low friction), which is robust against the application of normal load. The measured friction coefficients are essentially zero and independent of the external normal load up to a pressure of 1.67 MPa. The observation of load-independent superlubricity in micro-scale contacts is a promising result for numerous practical applications.