Increased elasticity and damping capacity of diamond-like carbon coatings by immobilized C60 fullerene clusters

Abstract

Material loss and plastic deformation induced by frictional interactions at moving mechanical interfaces continue to be major issues responsible for efficiency and performance degradation of systems. Establishment of fully elastic interactions in the contact region without compromising the structural rigidity and integrity of materials represents a promising solution. In this study, we report on improving the elasticity, damping properties, ductility and wear resistance of diamond-like carbon (DLC) coatings through introducing an immobilized C₆₀ cluster layer. The C₆₀ clusters were immobilized using cysteamine (HS(CH₂)₂NH₂) self-assembled monolayers (SAMs) attached to a pre-sputtered Au layer. A Ni adhesive layer was deposited onto plasma cleaned Si (100) substrates prior to Au, SAM-C₆₀, and DLC deposition. Precise dynamic ultra nano-indentation tests indicated a drastic improvement in elasticity and damping capacity of the C₆₀-DLC hybrid (Ni-Au-SAM/C₆₀-DLC) multilayer coating compared to those of the C₆₀-free (Ni-Au-DLC) multilayer. The behavior of the coatings under reciprocating contact conditions was evaluated. Quantification of the resistance of the coatings against wear and permanent deformation revealed a significant improvement in the wear rate from ∼3.38 × 10⁻⁸ to ∼5.14 × 10⁻¹⁰ mm³ N⁻¹ mm⁻¹ upon incorporation of the immobilized C₆₀ clusters. The corresponding mechanisms were assessed through experiments and finite element (FE) simulations.