Investigation of the properties of Ti-TiN-(Ti,Al,Nb,Zr)N composite coating and its efficiency in increasing wear resistance of metal cutting tools

The paper investigates the structure and the elemental and phase composition of Ti-TiN-(Ti,Al,Nb,Zr)N coatings, deposited using Filtered Cathodic Vacuum Arc Deposition (FCVAD) technology. The coating under study has a nanolayer architecture of outer (wear-resistant) material with a nanolayer thickness of 2-10 nm and ternary period of lambda = 180 nm. The experiments found that the wear-resistant coating layer was composed of a main cubic phase of (Ti,Nb,Zr,Al)N with the space group -Fm3m, as well as very small amounts of a h-AlN phase with the space group -P6.3mc. The distribution of elements within the ternary period varies in a wide range due to the planetary rotation of the substrate (Al varies within 1-20 at.%, Ti - 5-70 at.%, Zr - 3-30 at.%, and Nb - 3-40 at. %). The investigation includes comparative cutting tests of tools with the coating under study, as well as tools with Ti-TiN-TiAlN coatings with high (55 at.%) and low (16 at.%) aluminum content, and uncoated tools. The study considers the specifics of the wear patterns on carbide tools during the turning of workpieces made of AISI 1045 steel. The investigation is focused on the specifics of diffusion processes in the area of the interface of the coating and the material being machined. Both the diffusion of iron into the coating structure (to a depth not exceeding 100 nm) and the diffusion of coating elements (primarily titanium) into the structure of the material being machined (to a depth not exceeding 200 nm) are detected.