Investigation on the influence of oxygen on the deformation and cracking behavior of (Cr,Al)ON hard coatings using combinatorial static and dynamic loadings

The coating system (Cr, Al)ON can enhance the wear and corrosion resistance of tools applied in technical applications. It is possible that, under different loading conditions, the oxygen content of the coating could influence the performance of the coated tools. The aim of the present work is to study the influence of the oxygen content of the coating system (Cr,Al)ON on its elastic-plastic deformation and cracking behavior under static and dynamic loading conditions. For these purposes, three (Cr,Al)ON coatings with different oxygen contents were deposited on a quenched and tempered tool steel substrate AISI 420. The coatings were deposited using a hybrid technology combining direct current and high power pulse magnetron sputtering techniques in an industrial coating unit. The investigations were carried out by applying static loadings using nanoindentation and Rockwell tests as well as dynamic loading conditions using nanoscratch tests. Qualitative investigations were carried out using confocal laser scanning microscopy. The analyses of Rockwell imprints and nanoscratch tracks were conducted through scanning electron microscopy. Test results show that an improved understanding of possible crack formation in the coatings can be achieved through the analyses of nanoindentation force-displacement curves. Differences in the crack resistance of oxynitrides are more noticeable under dynamic loadings. Furthermore, coatings with a moderate value of oxygen content appear most promising in terms of mechanical and tribological behavior as well as crack resistance among the oxynitrides under investigation. Published by the AVS.