Assessment of AlTiN/TiSiXN Coating Characteristics in Selected Tribological Systems

This study examines the effect of an AlTiN/TiSiXN two-layer coating on the tribological performance of HS6-5-2C steel under dry friction conditions. Tribological assessments were conducted using a tribometer and a calotester with a ball-on-disc configuration, involving HS6-5-2C steel discs (both uncoated and coated with AlTiN/TiSiXN) and 100Cr6 steel balls. Analyses, including surface topography, microstructure, and chemical composition, were performed utilising confocal microscopy, atomic force microscopy, and scanning electron microscopy with energy dispersive spectroscopy. The hardness and elastic modulus of the coating and substrate were determined through nanoindentation techniques. The coating exhibited a hardness of approximately 38 GPa and high elasticity, substantially enhancing the tribological characteristics of the system. Notably, the coated specimens exhibited friction coefficients approximately 10% lower than those of the uncoated steel, while wear on the coated discs was reduced by more than 90% in comparison to their uncoated counterparts. Wear rate evaluations of the counter-samples indicated a slightly increased wear of the balls—approximately 21%—when in contact with the coated discs, which can be attributed to the high hardness of the coating. These results substantiate the superior efficacy of the AlTiN/TiSiXN coating in improving wear resistance and reducing friction.