X-ray Diffraction Studies of the Effect of Phase Composition and Structural State Characteristics on the Tribological Behavior of the Molybdenum- and Tungsten-based Strengthening Coatings

A comprehensive study of phase composition, structural state, parameters of fine atomic structure, mechanical and tribological properties of molybdenum-carbon and tungsten-carbon-based coatings deposited by reactive magnetron sputtering in an acetylene-argon gas mixture has been carried out. It has been shown that the resulting coatings have a nanocomposite diamond-like carbon (DLC) structure based on the metal and the metal carbide phases with close sizes of coherently diffracting domains (CDD), similar to 3-7 nm, and on hydrogenated amorphous carbon. The coating nanohardness values were 13-15 and 20-23 GPa for the Mo-DLC and W-DLC coatings, respectively. The tribological tests have demonstrated that the Mo- and W-DLC coatings can reduce friction and effectively protect the steel surfaces hardened by them both under dry friction and under boundary lubrication conditions.