Effect of Substrate Roughness on the Friction and Wear Behaviors of Laser-Induced Graphene Film

Abstract

A rough substrate usually induces severe detriments limiting the performance of anti-friction materials that would lead to an increase in both the friction coefficient and wear rate. In this work, we found that a laser-induced graphene (LIG) film had a good friction adaptability on both mirror-polished and rough Si substrates. The friction coefficient of the LIG increased from 0.11 to 0.24 and the substrate roughness increased from 1.4 nm to 54.8 nm, while the wear life of the LIG was more than 20,000 cycles for both the mirror-polished and rough Si substrates. Optical microscope, Raman spectroscopy and scanning electron microscope analyses revealed a friction mechanism evolution of the LIG films on Si substrates with a different roughness. For the mirror-polished Si substrate, thick and dense graphene nanocrystallite transfer films could form on the counterpart balls, which guaranteed a long and stable wear. For the rough Si substrate, although the asperities on the rough surface would plough the counterpart balls and destabilize the transfer film formation, grooves could effectively store a compressed LIG, benefiting a stable anti-wear performance and reducing the abrasive wear at the friction interface. This work showed that a LIG film had outstanding friction adaptability on Si substrates with a different roughness and that it can be fabricated in a single-step economic process, indicating bright practical prospects in the solid lubrication fields.