Nanotribology of ultrathin and hard amorphous carbon films

Abstract

One of the best materials to use in applications that require very low wear and reduced friction is diamond, especially in the form of a diamond coating. Unfortunately, true diamond coatings can be deposited only at high temperatures and on selected substrates, and they require surface finishing. However, the mechanical, thermal, and optical properties of hard, amorphous carbon – commonly known as a diamond-like carbon (DLCdiamond-like carbon (DLC)) coating – can be tailored to be similar to those of diamond. It can also be deposited at a wide range of thicknesses using a variety of deposition processes on various substrates at or near room temperature. The coatings reproduce the topography of the substrate, removing the need for surface finishing. Various physical and chemical characterization techniques have been used to study the structure, stoichiometry, and mechanical and tribological properties. The friction and wear properties of some DLC coatings make them very attractive for some tribological applications. The most significant current industrial applications of DLC coatings are in magnetic storage devices, micro/nanoelectromechanical systems, and various other consumer products including razor blades, sunglasses, and optical windows. In this chapter, the state-of-the-art in the chemical, mechanical, and tribological characterization of ultrathin amorphous carbon coatings as thin as 5 nm is presented.