Tribological properties and high speed drilling application of MoS2-Cr coatings

This study demonstrates that the properties of MoS2 coatings can be significantly improved through the co-deposition of an appropriate amount of chromium. The MoS2-Crx% coatings not only exhibit improved adhesion strength, microhardness and tribological properties, but also demonstrate an enhanced machining performance. This study investigates the tribological properties of the coatings under ball-on-disk point and cylinder-on-disk line contact wear modes using an oscillation friction and wear tester with a variety of counterbodies. Additionally, high-speed through-hole drilling tests are performed on PCBs to investigate the machining performance of the coated micro-drills. The results demonstrate that under the point contact wear mode, the optimal tribological properties are obtained using a MoS2-Cr8% coating sliding against a Si3N4 ceramic ball. Meanwhile, in the line contact wear mode, a MoS2-Cr5% coating sliding against a bronze cylinder or a MoS2-Cr8% coating sliding against a 6061 Al cylinder provides the optimal performance. Finally, it is shown that coating micro-drills with MoS2-Cr5% increases the tool life by a factor of two compared to uncoated drills when used for the high-speed through-hole drilling of PCBs under dry conditions.