Influence of tribological properties of Zr-ZrN-(Zr,Cr,Al)N and Zr-ZrN-(Zr,Mo,Al)N multilayer nanostructured coatings on the cutting properties of coated tools during dry turning of Inconel 718 alloy

The article studies the tribological properties of multicomponent nanostructured coatings of Zr-ZrN-(Zr,Cr,Al)N and Zr-ZrN-(Zr,Mo,Al)N, as well as the wear resistance and fracture behaviour of cutting tools with the mentioned coatings during the turning of Inconel 718 alloy. The Ti–TiN-(Ti,Cr,Al)N coating was also considered as a reference coating. While the Ti–TiN-(Ti,Cr,Al)N coating is characterized by high hardness, it also demonstrated high coefficients of friction (COF) at temperatures of 600 °C and above (i.e., at temperatures in the cutting zone). The Zr-ZrN-(Zr,Mo,Al)N coating has a balanced combination of high hardness and low COF at cutting zone temperatures. As a result, the Zr-ZrN-(Zr,Mo,Al)N-coated tool demonstrated wear resistance 2.4 times higher than that of the Ti–TiN-(Ti,Cr,Al)N-coated tool. During the process of cutting, zirconium (Zr) and chromium (Cr) oxides are formed in the Zr-ZrN-(Zr,Cr,Al)N coating, and the formation of zirconium and molybdenum (Mo) oxides is detected in the Zr-ZrN-(Zr,Mo,Al)N coating, which can have a positive effect on cutting conditions. Under the cutting conditions, the oxidizing action caused an almost complete transformation of a nitride coating structure into an oxide structure, while the nanolayer structure was partially preserved.