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

The structure and material properties of hydrogenated carbon films wer e studied and related to their tribological performance. Hydrogenated carbon films containing a range of 15-50 at. % of hydrogen were fabric ated by magnetron sputtering using a mixture of argon and hydrocarbon gases. Raman spectroscopy was used for determining the structure of th e H-C films. For physical property of H-C films, resistance of the fil m was measured. Nanohardness and elastic modulus of thin H-C films wer e also studied by measuring the load and displacement curve. The nanoh ardness and elastic modulus of H-C films were found to be very close t o those of diamondlike carbon films fabricated by chemical vapor depos ition. The stresses of H-C films were obtained by measuring the substr ate curvature before and after deposition. Thermal expansion coefficie nts of the H-C films were obtained by measuring the change of stress o f H-C film deposited on two known substrates as a function of temperat ure. The accelerated drag and contact start stop tests of H-C films we re performed in various gas environments and it was found that the bes t tribological performance was obtained from the H-C overcoat with the highest hydrogen concentration.