Self-lubricating chromium carbide/amorphous hydrogenated carbon nanocomposite coatings: A new alternative to tungsten carbide/amorphous hydrogenated carbon

Abstract

In the automotive industry, there is an increasing demand to apply self-lubricious coatings to reduce fuel and oil consumption. Within this work, self-lubricious nanocomposite coatings consisting of 1-3.5 nm sized CrC nanocrystals embedded in an amorphous hydrogenated carbon (a-C:H) matrix have been developed in a laboratory-scale sputtering system and up-scaled to a production-type plant. The nanostructure and composition of these coatings are presented and correlated to mechanical and tribological properties. With hardness values of about 11 GPa, dry-sliding friction coefficients between 0.08 and 0.18, and wear rates between 3.9×10⁻¹⁶ and 2.8×10⁻¹⁵ m³/N/m, the coatings outperform present state-of-the-art WC/a-C:H coatings and seem to be excellent candidates for applications in automotive engines and drivetrain systems.