EFFECT OF NITROGEN DOPING ON FRICTION AND WEAR PROPERTIES OF THICK TETRAHEDRAL AMORPHOUS CARBON COATING

In the present study, the coating was deposited by the filtered cathode vacuum arc (FCVA) plasma technique, and the effect of the nitrogen gas doping on the friction and wear performances of the thick layer of nitrogen-doped tetrahedral amorphous carbon (ta-C:N) coating were investigated. The tribological behavior of the coating was investigated by sliding an SUJ2 ball over the coating in a ball-on-disk tribo-meter. The experimental results revealed that doping using a high nitrogen gas flow rate improved the wear resistance of the coating, while a low flow rate of 0-10 sccm increased the coefficient of friction (CoF) and wear rate dramatically decreased when the nitrogen flow rate was increased to 30-40 sccm. This was due to the nitrogen-induced phase transformation, resulting in the production of a graphite-like structure in the interface between disk and SUJ2 ball. The widths of the wear track and wear scar were also observed to decrease with increasing nitrogen flow rate. Moreover, the G-peaks of the wear scar around the SUJ2 ball on the worn surface increased with increasing nitrogen doping.