Ti- and Cr-based hard coatings obtained at low temperatures by unbalanced magnetron sputtering

Abstract

We prepared a set of Ti- and Cr-based ternary and quaternary hard coatings at low deposition temperatures (< 200 °C) by closed-field unbalanced magnetron sputtering in a gas mixture of Ar + N2. The morphological, structural and mechanical properties of the coatings were characterized by means of atomic force microscopy, scanning electron microscopy, X-ray photoelectron spectrometry, a micro-scratch tester and a nanoindentation tester. The results of the analyses performed revealed that the surface of the deposited ternary Ti-Al-N coatings was rougher than that of the CrTiAlN coatings. The metallic elements in the coatings react with nitrogen to form CrN, TiN and AlN nitride phases, as no Cr2N phase was detected in the Cr-based coatings. The optimized quaternary coating demonstrated mechanical properties superior to those of the ternary ones in terms of hardness; adherence strength of 32 GPa and elastic modulus of 418 GPa were measured for the multicomponent coating of composition Cr0.68Ti0.19Al0.13N.