Friction and Wear Properties of Si-containing H-free Amorphous Carbon-based Films

To investigate the effect of Si incorporation on friction and wear properties of H-free amorphous carbon-based films, Si-containing H-free amorphous carbon films were deposited on Si and 304 stainless steel substrates by direct current magnetron sputtering method. The composition, structure and mechanical properties of the films were examined by scanning electron microscopy (SEM), Raman spectra, nanoindenter and other techniques. The tribological properties of the films were tested in dry contact conditions using a reciprocating sliding tribometer with ball-on-disk contact geometry. The results indicate that Si incorporation reduces the residual stress of films and promotes the sp~3 hybridization. The film hardness is increased by Si incorporation over 10%. The addition of Si has little influence on friction coefficient of H-free carbon film under various wetting conditions. Si-doped films show higher wear rates than the H-free film, and their wear rates increase with increasing Si contents and decreasing relative humidity. High Si content within films causes significant instability of friction coefficient and leads to severe wear of the films in the low humid air. This suggests that the degradation in performance resulting from Si doping should be fully considered in designing and developing H-free amorphous carbon-based tribological coatings with excellent properties