The tribological behavior of W-S-C films in pin-on-disk testing at elevated temperature

W-S-C films were deposited by magnetron sputtering in an Ar atmosphere with a Ti interlayer. A carbon target with several pellets of WS(2) incrusted in the zone of the preferential erosion was used. The number of pellets was changed to modify the carbon content in the films, which varied from 29 up to 70 at%. Doping W-S films with carbon led to a substantial increase of the hardness in the range 4-10GPa; the maximum of hardness was obtained for coatings with the carbon content of 40 at%. X-ray diffraction (XRD) patterns showed that there was a loss of crystallinity with the increase of the carbon content in the film. The coatings were tested by pin-on-disk from room temperature (RT) up to 400 degrees C. At RT, the friction coefficient was in the range 0.2-0.30. At temperatures higher than 100 degrees C, the friction is below 0.05 for all compositions. The tribological behavior of the coatings with increasing temperatures depended on the films carbon content. For low-carbon content up to 40%, the wear rate was almost independent of the temperature up to 300 degrees C, while it increased dramatically in the case of the coatings with high-carbon content. In general, the limiting temperature for W-S-C coatings is 400 degrees C. (C) 2007 Elsevier Ltd. All rights reserved.