Structural engineering of nbn/cu multilayer coatings by changing the thickness of the layers and the magnitude of the bias potential during deposition

Abstract

To determine the patterns of structural engineering of vacuum-arc coatings based on niobium nitride in the NbN/Cu multilayer composition, the effect of layer thickness and bias potential on the structural-phase state and physico-mechanical characteristics of vacuum-arc coatings was studied. It was found that the metastable δ-NbN phase (cubic crystal lattice, structural type NaCl) is formed in thin layers (about 8 nm thick) regardless of Ub. With a greater thickness of the layers of niobium nitride (in the multilayer NbN/Cu composition), the phase composition changes from metastable δ-NbN to the equilibrium ε-NbN phase with a hexagonal crystal lattice. An increase in the bias potential during deposition from-50 to-200 V mainly affects the change in the preferential orientation of crystallite growth. The highest hardness (28.2 GРa) and adhesive resistance is achieved in coatings obtained at Ub =-200 V with the smallest layer thickness. The highest hardness corresponds to the structurally deformed state in which the crystallite texture is formed with the [100] axis perpendicular to the growth surface, as well as a large microstrain (1.5%) in crystallites.