engleski

THE MECHANICAL PROPERTIES OF DISORDERED TUNGSTEN-CARBON THIN FILMS

Tungsten-carbon thin films were prepared by reactive magnetron sputtering operated in argon + benzene gas mixture. The effects of benzene partial pressure (1,25-6,5%), substrate temperature (r.t.-400°C) and substrate bias voltage were investigated. Structure of the films is dominated by WC1-x nonstoichiometric carbide, imbedded with the unbound carbon. In the low-carbon-content films the WC1-x matrix structure changed from strongly disordered (111)-textured structure to small-grained microcrystalline (200)-textured structure with the temperature increase, while the structure in high-carbon-content films is a strongly disordered (111)-textured WC1-x in all cases (grain sizes being 7-16 nm). The amount of segregated carbon and the ratio between disordered and graphitic components of unbound carbon increased with substrate temperature and more strongly with the benzene partial pressure. The micromechanical properties of the films are governed mostly by the total amount of unbound carbon: the nanohardness decreases from 29-34 GPa for the films produced with the 1,25% and 2,5% benzene admixture to 13-30 GPa for the films prepared with 5% benzene.

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