MATERIAL PROPERTIES AND TRIBOLOGICAL PERFORMANCE OF HYDROGENATED SPUTTER CARBON OVERCOAT ON RIGID DISK

The structure and material properties of hydrogenated carbon films were studied and related to their tribological performance. Hydrogenated carbon films containing a range of 15-50 at. % of hydrogen were fabricated by magnetron sputtering using a mixture of argon and hydrocarbon gases. Raman spectroscopy was used for determining the structure of the H-C films. For physical property of H-C films, resistance of the film was measured. Nanohardness and elastic modulus of thin H-C films were also studied by measuring the load and displacement curve. The nanohardness and elastic modulus of H-C films were found to be very close to those of diamondlike carbon films fabricated by chemical vapor deposition. The stresses of H-C films were obtained by measuring the substrate curvature before and after deposition. Thermal expansion coefficients of the H-C films were obtained by measuring the change of stress of H-C film deposited on two known substrates as a function of temperature. The accelerated drag and contact start stop tests of H-C films were performed in various gas environments and it was found that the best tribological performance was obtained from the H-C overcoat with the highest hydrogen concentration.