Tribological Behavior of ta-C Coating Originated by Surface Defects

During the fabrication process of tetrahedral amorphous carbon (ta-C) via filtered cathodic vacuum arc, inevitable surface defects arise, impacting tribological properties. Our investigation focused on the resulting deterioration in high-temperature tribological behavior. We found that by applying a duct bias to filter macroparticles, the friction-wear characteristics of ta-C could be improved. Specifically, a duct bias of 30 V reduced defect density to less 1%, contrasting with 4% observed with a 0 V bias. Additionally, in defect-rich ta-C samples, we observed unstable friction and severe abrasive wear, attributed to the accumulation of wear debris and three-body abrasion around pores within the wear track. This degradation in friction and wear primarily resulted from tribo-fracture induced by tensile cracks in oxidized pores.