Effects of nitrogen flowrates on properties of TiSiN coatings deposited by arc ion plating combining with medium-frequency magnetron sputtering

• TiSiN coatings were deposited by AIP combining with MF magnetron sputtering.
• Increasing nitrogen flowrate largely decreased Si target voltage and Si contents.
• Edge effect was found that Si contents in edge regions were less than central areas.
• Edge effect was diminished with the increase of nitrogen flowrate.
• TiSiN coating deposited at 180 sccm had the best tribological performance.

TiSiN coatings were deposited on WC/TiC/Co cemented carbides by arc ion plating combining with medium-frequency magnetron sputtering at different nitrogen flowrates, where one arc target of Ti and two magnetron targets of Si were used. The effects of nitrogen flowrate on Si content, microstructure, hardness and tribological behaviors of TiSiN coatings were investigated. Results showed that Si content and deposition rate of TiSiN coatings largely decreased as nitrogen flowrates increased. The coatings had a maximum hardness 34.3 GPa at nitrogen flowrate of 180 sccm with the Si content of 7.45 at.%. Edge effect was found in all specimens, resulting in less Si contents in edge regions compared to central areas. Edge effect was diminished with the increase of nitrogen flowrates due to the decreased re-sputtering effect. Dry sliding tests against 40Cr hardened steel ball showed friction coefficient decreased and wear mechanism changed from adhesive wear, to abrasive wear, and to flaking with increasing nitrogen flowrate. The coating deposited at 180 sccm had the best tribological performance with the wear rate of 1.73 × 10− 6 mm3/N·m and without obvious adhesion or flaking.