Effect of HG40 and HS123 hard alloy tool substrates on the properties of hardening coating

Abstract

This article examines the impact of surface and near-surface layer properties of a hard alloy on the physico-mechanical and tribological properties of Mo–Ti–Ni–Si–Al–N CAPVD-coatings deposited on HG40 and HS123 cutting tools. In both cases, the coatings had similar composition, multilayer architecture, and nanograin structure, with crystallite sizes ranging from 6 to 10 nm. However, there were significant differences in the hardness, elasticity modulus, and relative work of plastic deformation between the coatings. Specifically, on HG40 substrates, the hardness, elasticity modulus, and relative work of plastic deformation were equal to 27.6 GPa, 647 GPa and 38.2 %, respectively, while on HS123 substrates, they were 34.2 GPa, 481 GPa and 46.2 %, respectively. Furthermore, coatings formed on HS123 hard alloy demonstrated superior wear resistance and stronger adhesion. This can be attributed to the presence of higher compressive macrostresses within the coating. The maximum value of this property, approximately 5.2 GPa, was achieved when deposed to HS123 hard alloy, whereas the coating applied to HG40 reached a maximum value of approximately 3.2 GPa. Additionally, a more extensive diffusion zone between the substrate and coating components, along with associated structural phase heterogeneity, was observed at the coating-substrate interface when applied to HS123 substrate.