Tribological behavior of Ti–Si–N coating layers prepared by a hybrid system of arc ion plating and sputtering techniques

Ti–Si–N coating layers were deposited onto WC–Co substrates by a hybrid system of arc ion plating and sputtering. The coating layers were prepared with different Si contents to investigate the effect of Si content on their tribological behaviors. For this study, the dry sliding wear experiments were conducted on Ti–Si–N-coated WC–Co discs at three different sliding speeds, 0.1, 0.3, 0.5 m/s, against steel (SUJ2) and alumina balls using a conventional ball-on-disc sliding wear apparatus. In the case of steel ball, the average friction coefficient slightly decreased with increasing the sliding speed regardless of Si content, due to adhesive wear behavior between coating layer and steel ball. At constant sliding speed, the average friction coefficient decreased with increase of Si content. This behavior was attributed to the formation of self-lubricating tribo-layers such as SiO2 or Si(OH)2. Conversely, in the case of the alumina ball, the average friction coefficient increased with increasing sliding speed regardless of Si content, indicating that the abrasive wear behavior was more dominant when the coating layers slid against an alumina ball. From our experimental results, it was found that the tribological behavior of Ti–Si–N coating layers was affected by factors such as Si content, sliding speed, and type of counterpart materials.