Atomistic Tribology Simulations of Hard Carbon Coatings - from Dry Friction to Boundary Lubrication

Owing to their extraordinary combination of mechanical properties, thermal conductivities and chemical inertness, carbon hard coatings, such as nanocrystalline diamond and diamond-like amorphous carbon, have recently drawn attention for superlubricity applications (Ù<0.01) in a broad range of engineering systems. Yet, despite many efforts to understand phenomena occurring at buried sliding interfaces, they still remain elusive. Atomistic simulations of friction between two surfaces in relative motion have been of increasingly importance to gain insights into the physical and chemical origin of friction and wear. They can be also utilized for designing custom-tailored lubricants and superlubricious interfaces. This article reviews state-of-the-art results of atomistic simulations in tribology of diamond and diamond-like amorphous carbon surfaces in both dry friction and boundary lubrication with water and organic friction modifiers such as fatty acids and glycols.