Mechanical and tribological properties of the High Target Utilization Sputtering W-C coatings on different substrates

The effects of three types of substrates (Si, bearing steel, and WC-Co) and acetylene addition (0–3.2vol.% in Ar atmosphere) on the topography, structure, composition, nanohardness and tribological behavior of the High Target Utilization Sputtering W-C coatings were investigated. The results showed that the substrates affected mostly the coating topography, roughness and nanohardness whereas the composition, indentation moduli and coefficients of friction were influenced only by the increase of free carbon content from acetylene addition. Up to ~5GPa difference in the hardness of the W-C coatings on Si substrates compared to that on steel was obtained. Simultaneously, methodological problems with the hardness measurements were identified on WC-Co substrate which has the hardness close to that of the coatings. The average values of the coefficient of friction were around 0.3 and slightly decreased at higher carbon contents but the influence of the substrates was small.