Deposition and characterization of nanostructured metal/carbon composite films

Abstract

Films with high hardness and reduced friction coefficient are required for the protection of materials surface against wear in sliding contacts. The surface of hard coatings can be covered with solid lubricant films for lubrication of sliding contact operating under extreme conditions. Molybdenum disulfide (MoS 2) and diamond-like carbon (DLC) films used currently as lubricant films for various applications may exhibit severe limitations related to the stability of films in oxidizing or humid atmosphere. Carbide forming metal/carbon (Me/C) composite films with Me=Ta, W or Ti possess appropriate properties to overcome the limitation of MoS 2 and DLC films. Metal/carbon composite films involving metal inert with respect to carbon can be of interest as wear-resistant and low friction films for tribological applications. Various deposition techniques such as sputtering, arc discharge, plasma-enhanced chemical vapor deposition, pulsed laser ablation can be used to produce films containing metal clusters dispersed in the amorphous carbon matrix. Nanostructured copper/amorphous hydrogenated carbon (a-C:H) films have been deposited on Si substrates by an hybrid technique combining microwave plasma-assisted chemical vapor deposition and sputtering of a Cu target from acetylene or methane–argon mixtures. The composition and microstructure of Cu/a-C:H composite films were determined as functions of the gas phase composition. Composite films with a self-organized laminated microstructure were deposited from CH 4–Ar mixtures containing 10–60% of CH 4 under low energy ion bombardment. The hardness, H, Young modulus, E, and plastic deformation parameter, H 3/ E 2, of films were investigated as functions of the carbon content. The friction coefficient of Cu/a-C:H films produced from CH 4–Ar mixtures with a laminated microstructure was significantly lower than that of DLC films in humid atmosphere.