Application of nanostructured Zr-ZrN-(Zr,Al)N and Zr-ZrN-(Zr,Cr,Al)N coatings for improvement of tool life and performance in end milling of carbides

The paper deals with the challenges of improving the tool life of end mills and performance in end milling of carbides through application of tools with the nanostructured Zr-ZrN-(Zr,Al)N and Zr-ZrN-(Zr,Cr,Al)N coatings, deposited using the filtered cathodic vacuum arc deposition (FCVAD) technology. The main mechanical characteristics of the above coatings (microhardness and critical fracture load) were determined. The cutting properties were investigated at mill rotation frequency of n = 1250, 1600, 2000 rpm. Samples were compared with uncoated tools and with tools with commercial coatings, including monolayer Ti-TiN and nanostructured Ti-TiN-(Ti,Al)N coatings. The studies have proved that the proposed coatings are not only able to improve the tool life, but they also allow milling at higher mill rotation frequency, and, consequently, with higher performance of milling. Meanwhile, tools with the Zr-ZrN-(Zr,Al)N and Zr-ZrN-(Zr,Cr,Al)N coatings are characterized by more balanced pattern of wear, without visible signs of brittle fracture. (paper)