Nanoscale architecture of ZrN/CrN coatings: microstructure, composition, mechanical properties and electrochemical behavior

Abstract

The main aim of this study is to develop ZrN/CrN nanolayered coatings with bilayers periods 10 bilayers (10 L), 20 bilayers (20 L) and 30 bilayers (30 L) over AISI 304 stainless steel and also evaluating the effect of nanolayers architecture on their electrochemical behavior. The nanolayers were deposited from chromium and zirconium targets using the cathodic arc evaporation physical vapor deposition (Arc-PVD) technique in a nitrogen atmosphere. The nanolayer microstructure and morphology were evaluated using X-ray diffraction (XRD), atomic force microscopy (AFM), and field emission scanning electron microscopy (FE-SEM). The chemical composition was studied by energy-dispersive X-ray spectroscopy (EDS) tests. The electrochemical characterization was carried out by potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) tests in 3.5 wt. % NaCl solution in order to investigate changes in the electrochemical behavior as a function of the deposited bilayers number. The existence of CrN and ZrN phases with FCC lattices in the nanolayers were identified by the XRD patterns. The FE-SEM observations showed that the multilayered coatings were deposited at an excellent periodicity. The electrochemical tests indicated that the corrosion resistance of ZrN/CrN nanolayers is enhanced by increasing the number of bilayer periods that can be ascribed to the decrease in the pinholes and blocking the penetration path of corrosive solution.