CrVN/TiN nanoscale multilayer coatings deposited by DC unbalanced magnetron sputtering

Abstract

The growing interest in development coatings with enhanced properties opened the door to the research and development of nanoscale multilayer coatings. Some of the most interesting properties of these multilayer coatings when compared to monolayers are hardness higher than 40GPa, friction coefficients <0.3, improved adhesion and increased heat and corrosion resistance.In this work, CrVN/TiN nanoscale multilayer coatings were deposited onto H13 steel substrates by DC unbalanced magnetron sputtering. For the deposition of the multilayer coatings, two targets of Cr-V (70–30wt%) and Ti (99.5wt%) confronted opposite each other were used. In order to vary the bilayer period, a microcontroller was used to control the rotation and residence time of the substrates in front each target, thereby obtaining multilayer periods of 15nm, 30nm and 43nm. CrVN and TiN monolayer coatings were also deposited.X-ray diffraction (XRD) showed a FCC crystal structure for all coatings. SEM images revealed a columnar structure for CrVN and a cauliflower-like structure for TiN, similar to that obtained for the multilayer coating. All coatings showed a Hardness and Young's modulus around 19GPa and 270GPa, respectively. The CrVN/TiN multilayer with a period of 15nm showed the lowest friction coefficient (0.31) and the lowest wear rate (2.23×10−9kg/Nm) of all coatings, representing a reduction of 36% compared to the friction coefficient of H13 steel and a reduction in the wear rate of three orders of magnitude compared to the TiN. Finally, it was possible to identify three stages in the wear mechanism in the multilayer coatings, the lowest period, molecule-to-molecule adhesive wear occurred, followed by a rupture in the TiN and CrN bonds when the period increased to 30nm, while with the highest period of 43nm, oxides of titanium, chromium and vanadium were formed.