Correlation between three-body wear and tribological characteristics of titanium nitride, titanium carbonitride and titanium carbide coatings

The tribological characteristics of the TiN, TiC and Ti(C,N) coatings related to three-body abrasions were studied in this work. Eight types of coating films were deposited by means of the cathodic arc ion plating process by varying the mass flow rates of nitrogen and acetylene gases during the coating processes. The lower specimens were coated by the titanium film as the underlayer and the TiN, TiC or Ti(C,N) film as the top layer. The influences of the three-body wear on various parameters, including mean friction coefficient, the fluctuations of friction coefficient, electrical voltage and specimen temperature, were discussed. The fluctuation intensity in the friction coefficient curve is affected by the mean size of the wear debris entrapped between two rubbing surfaces. Three-body wear is more often produced in the ceramic coatings which was operated at a lower specimen temperature or at a higher sliding speed while the specimen temperature was still low. If the specimen temperature was raised high enough, the three-body wear was gradually diminished because brittle fracture was impeded by the thermal effect. Wear mechanisms occurring in the Ti(C,N) coatings are much dependent upon the operating conditions and less affected by the change in the chemical composition of ceramic coating.