Optimized a-C coatings by doping with zirconium for tribological properties and machining performance

In this study, a-C:Zr_x% coatings with various levels of zirconium (Zr) addition are deposited on cemented tungsten carbide (WC-Co) substrates using a medium frequency twin magnetron sputtering and unbalanced magnetron sputtering system. The tribological properties of the coatings are investigated by conducting wear tests against an AISI 1045 steel counterbody under a cylinder-on-disk line contact wear mode using an oscillating friction and wear tester system. The machining performance of coated turning cutters and micro-drills is then evaluated by performing turning tests and high-speed through-hole drilling tests using AISI 1045 steel counterbodies and printed circuit board workpieces, respectively. The experimental results reveal that the fabricated a-C:Zr_x% coatings not only have improved tribological properties, but also yield an enhanced machining performance. For sliding against the AISI 1045 steel counterbody under loads of 10 N and 100 N, respectively, the optimal tribological properties are provided by the a-C:Zr_13%coating. However, the optimal turning and drilling performance is obtained using the a-C: Zr_45% coating.