Design of AlCrSiN multilayers and nanocomposite coating for HSS cutting tools

Abstract

In the present work, AlCrN coating and AlCrSiN multilayer and nanocomposite coating were designed and deposited on the surface of high speed steel (HSS) cutters. The microstructures of these coatings were investigated systematically by means of grazing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscope (XPS), electron probe X-ray microanalysis (EPMA), scanning electron microscope (SEM) and high-resolution transmission electron microscope (HRTEM), in association with mechanical property measurement and corresponding cutting test. The results showed that the AlCrN coating mainly composed of nanocrystalline fcc-CrN, hcp-AlN and fcc-(Cr,Al)N solid-solution. In addition to these nanocrystalline phases, a few amorphous Si3N4 phases were observed for the AlCrSiN multilayers and nanocomposite coating with a stronger {200} preferred orientation. The modulation period (6nm) of the AlCrSiN coating was much smaller than that of the AlCrN coating (18nm). The service life of the AlCrSiN coated tool increased approximately 40% longer in comparison with the AlCrN coated tool because of its more excellent mechanical properties (48GPa hardness, 1123MPa toughness, 52N LC2 adhesion strength and 0.25 average friction coefficient). During the cutting process, the wear mechanisms of coated tools at the early stage and mid-stage were abrasion wear and adhesion wear, respectively. And the worn loss of AlCrSiN coated tool was less than that of AlCrN coated tool.