Deposition and Tribology of Electroconductive and Wear-Resistant Nanocomposite Solid Lubricant Films Composed of Carbon and Silver or Gold

Abstract

The hardness and Young’s modulus of electroconductive solid lubricant films were increased using a nanocomposite structure to enhance their endurance. Moreover, both carbon and a soft metal, which have solid lubricating properties, were used in the films to decrease their shearing strength. Nanocomposite films composed of carbon and silver or gold (DLC-Ag or Au) films were deposited by biased radio frequency sputtering of carbon and gold or silver targets, respectively. The hardness of the (DLC-Ag or Au) nanocomposite films deposited using sector targets was higher than those of nanocomposite films deposited with semi-circular and diamond-like carbon (DLC) targets, as well as single-layer Ag and Au films. Nanoindentation tests revealed that the nanocomposite films exhibited higher hardness and elastic modulus, and lower modulus of dissipation and material plastic factor, than the single-layer films. The friction coefficient of the nanocomposite films was lower than that of carbon, gold, and silver single-layer films. The nanocomposite films deposited using a sector target also showed the least damage and superior sliding endurance life. Because of their low damage rate, the rate of increase in the electrical resistivity of the nanocomposite films during sliding tests was lower than those observed for the single-layer films.