Friction and wear behaviors of MoS₂/Zr coated HSS in sliding wear and in drilling processes

MoS₂ metal composite coatings have been successful used in dry turning, but its suitability for dry drilling has not been yet established. Therefore, it is necessary to study the friction and wear behaviors of MoS₂/Zr coated HSS in sliding wear and in drilling processes. In the present study, MoS₂/Zr composite coatings are deposited on the surface of W6Mo5Cr4V2 high speed steel(HSS). Microstructural and fundamental properties of these coatings are examined. Ball-on-disc sliding wear tests on the coated discs are carried out, and the drilling performance of the coated drills is tested. Test results show that the MoS₂/Zr composite coatings exhibit decreases friction coefficient to that of the uncoated HSS in sliding wear tests. Energy dispersive X-ray(EDX) analysis on the wear surface indicates that there is a transfer layer formed on the counterpart ball during sliding wear processes, which contributes to the decreasing of the friction coefficient between the sliding couple. Drilling tests indicate that the MoS₂/Zr coated drills show better cutting performance compared to the uncoated HSS drills, coating delamination and abrasive are found to be the main flank and rake wear mode of the coated drills. The proposed research founds the base of the application of MoS₂ metal composite coatings on dry drilling.