Novel tertiary dry solid lubricant on steel surfaces reduces significant friction and wear under high load conditions

Abstract

A novel graphene-zinc oxide composite film is created and studied as a solid-state lubricant for friction and wear reduction under extreme load conditions. The liquid-free composite is made from a slurry of graphene, zinc oxide, and polyvinylidene difluoride spin-coated onto a stainless steel substrate. Enhanced tribological performance was measured under ambient conditions using a ball-on-disk tribometer with contact pressures up to 1.02 GPa and sliding distances up to 450 m. The graphene-rich lubricant demonstrates substantial friction and wear reduction (ca. 90%) compared to unlubricated sliding. The composite film is able to maintain its lubricating effects under extreme operating conditions including 15 N normal load and 450 m sliding distance. Following tribological testing, optical and spectroscopic analysis of the formed wear scars reveal a persistent protective film on the ball and disk surfaces. The excellent tribological performance of this graphene-rich composite is attributed to the adhesion effect from zinc oxide: zinc adheres graphene to the contact interface, maintaining improved tribological performance under high contact pressure. The durability and resilience of this adhesive coating suggest exceptional potential as a dry lubricant for high load-bearing applications.