Phase composition and tribological properties of copper/carbon composite films

Copper/carbon composite films have been deposited on steel and silicon substrates by an hybrid technique combining sputter-deposition of copper and microwave plasma-assisted chemical vapor deposition of carbon from argon–methane mixtures of various concentrations.The composition of films was determined by Rutherford backscattering spectroscopy (RBS) and energy recoil detection analyses (ERDA). The crystallographic structure of films was identified by X-ray diffraction (XRD) techniques. The dry friction properties of films were investigated by ball-on-disk tribological tests conducted at room temperature in room air.Copper/carbon films containing 25–75 at.% of carbon were produced as the methane concentration in the gas phase was varied from 20% to 100%. These composite films consisted of copper crystallites and hydrogenated amorphous carbon (a-C:H) phase. The size of copper crystallites was in the range 2–20 nm. An abrupt increase in carbon content in the films was observed as the methane concentration in the gas phase increased from 60% to 70%.The tribological behavior tested in ball-on-disc geometry and microhardness of these Cu/a-C:H composite films are analyzed and discussed in terms of their microstructure, morphology and composition.