Nanofriction behavior of cluster-assembled carbon films

TL;DR

This study investigates the nanofriction properties of cluster-assembled carbon films using AFM, confirming a modified friction law and analyzing the effects of nanostructure and humidity on adhesion and friction coefficients.

Contribution

It introduces a modified Amonton's law for nanostructured carbon films and validates it through molecular dynamics simulations and experimental measurements.

Findings

Friction coefficient is unaffected by nanostructure and humidity.

Adhesion coefficient depends on nanostructure and humidity.

Molecular dynamics simulations support the friction model.

Abstract

We have characterized the frictional properties of nanostructured (ns) carbon films grown by Supersonic Cluster Beam Deposition (SCBD) via an Atomic Force-Friction Force Microscope (AFM-FFM). The experimental data are discussed on the basis of a modified Amonton's law for friction, stating a linear dependence of friction on load plus an adhesive offset accounting for a finite friction force in the limit of null total applied load. Molecular Dynamics simulations of the interaction of the AFM tip with the nanostructured carbon confirm the validity of the friction model used for this system. Experimental results show that the friction coefficient is not influenced by the nanostructure of the films nor by the relative humidity. On the other hand the adhesion coefficient depends on these parameters.