Effect of defects on tribological behavior in ta-C coating deposited by Filtered Cathodic Vacuum Arc technique

This study examined the tribological behavior of a ta-C coating fabricated at a substrate bias of -100 V via filtered cathodic vacuum arc (FCVA) deposition. Defects in the ta-C coating were categorized as droplets, pores, and spikes, considering the morphological, structural, and mechanical properties of the ta-C surface. A friction test was conducted at 170 °C in ambient air using a ball-on-disk tribometer. The friction coefficient was 0.08 during the steady state and the wear rate was 4.3×10⁻⁶ mm³/Nm. To explain the friction and wear behavior, the morphological and structural properties of the defects in the designated area were compared among different sliding cycles. The droplet is almost detached and some pores can be generated from spot where droplet was presented. Spalling of these spikes produced abrasive particles that caused severe wear at pores possessing a sp²-rich structure and poor mechanical properties.