Investigating running-in behavior to understand wear behavior of ta-C coating with filtered cathodic vacuum arc deposition

In this study, to clarify running-in cycle and role of carbon transfer layer on wear, ta-C coatings were subjected to friction tests under 200 °C in air with a different sliding cycles. The steady state friction coefficient of 0.02 was obtained after finishing a running-in cycles approximately 2,000 cycles. During the steady state, wear rate of ta-C decreased with increasing number of cycles. Such the decrease of wear rate was explained by polished defects presented on surface and form carbon transfer layer on the counter-part material. The mechanism of those tribological properties was analyzed by Raman spectroscopy, scanning electron microscope observation and 3D measuring laser microscope.