Effect of Nitrogen Partial Pressure on Structure, Mechanical Property, and Corrosion Behavior of ZrN_x Films Prepared by Reactive DC Magnetron Sputtering

ZrN_x films were deposited by DC magnetron sputtering with pure Zr target in different nitrogen partial pressure atmospheres (r = N₂/[Ar + N₂]). The structure and composition of the thin films were characterized as a function of r using scanning electron microscope, glancing angle X-ray diffraction, and X-ray photoelectron spectroscopy. The hardness, adhesive strength, and corrosion behavior of the coatings were measured by nanoindentation, microscratch, and potentiodynamic measurements in 3.5 wt% NaCl solution. The results show that the structure of the ZrN_x films changes from a nearly stoichiometric ZrN with a typical columnar structure to mixed phases composited of ZrN and α-ZrN_x with a dense glass structure as r increases from 12% to 50%. The mechanical properties including hardness, elastic modulus, and adhesion decrease with increasing r due to nonstoichiometric compound and glass phase structure of the coatings, while the dense glass structure significantly improves the corrosion inhibition.