Microtexturing of TiZrN-Coated Si₃N₄ cutting inserts for machining nickel alloy

Moscow State University of Technology “STANKIN”, Department of High-Efficiency Processing Technologies, Vadkovskiy per. 1, Moscow, 127994, Russia

^* Corresponding author: a.okunkova@stankin.ru

Published online: 17 February 2025

Abstract

Insulating cutting ceramics exhibit outstanding mechanical and thermal properties but have electrical conductivity below the percolation threshold. It does not allow sophisticated shapes to be obtained by diamond grinding and polishing. The developed innovative technique is based on choosing the wear-resistant coating based on the chemical composition of the cutting ceramics and its behaviour at 1000–10 000°C, including changing the electrical conductivity from insulating to conducting level, dissociation/sublimation of its components and forming new conductive compounds during cooling that improves the conductive conditions in the interelectrode gap. Thus, the coating plays a wear-resistant role and serves as a technological asset in shaping methods based on the electrical destruction of the materials under discharges. TiZrN coating was deposited on a Si₃N₄ cutting insert using the vacuum-plasma method, with a thickness of 3.8–4.0 μm. The ceramics was microtextured by powder-mixed wire electrical discharge machining in TiO₂-suspension, d_w = 0.25 mm. The coated samples were subjected to adhesion and wear-resistance tests. Failure criterion in machining XH45MBTJuBP alloy was chosen a chamfer of 400 μm. The durability of the TiZrN-coated Si₃N₄ ceramic insert was improved by 1.33.