Formation of a Tribofilm in the Surface Layer of Al–Ti–Cr–N–B Magnetron Coating on Boron Nitride During Turning of Hardened Steel

Abstract

The effect of cutting ShKh15 hardened steel on the element and phase composition of the surface layer of the coating deposited on the cBN-based tool is studied. The microstructure and oxidation kinetics of the surface layer of the AlN-Ti(Cr)B 2 magnetron coating are investigated during both formation and turning. The coating is formed by HF magnetron sputtering of an AlN-Ti(Cr)B 2 target. The formation of a two-layer tribofilm with a nanosize outer layer is examined. The phase composition of the tribofilm is determined using layer-by-layer Auger analysis. Its outer nanosize layer is a glass-like phase in the form of limited solid solutions based on Al 2 O 3 oxides and playing a role of solid lubricant. As the cutting speed is increased, the wear rate for the coated tool decreases compared with the uncoated tool.