The Effect of the Nitrogen Percentage on the Microstructure and Mechanical Properties of Zr-N Coatings

 Nitride-based hard coatings have attracted increasing interest over the last decades for machining, and cutting tool applications, owing to their high hardness, high thermal stability, good wear, and corrosion resistance. In this work, we investigated the effect of nitrogen concentration, as a reactive gas, on the structure and properties of Zr-N coatings deposited by magnetron sputtering. The structural and morphological properties of Zr-N films were described, followed by a detailed investigation of the mechanical properties of Zr-N coatings. By varying the nitrogen percentage, the structure and the hardness of Zr-N films were evaluated in a wide range. With a rising N2 percentage, the structure changed from Zr2N at 10% N2 to a mixture of Zr2N and Zr N from 20%N2 with the NaClB1 -type structure. Insertion of nitrogen atoms on the Zr leads to significant changes in film microstructure, grain size, and surface morphology, as evidenced by x-ray diffraction, scanning electron and atom. The hardness of the films was first augmented by increasing the nitrogen percentage and take a maximum value was 22 GPa for the films deposited under 20%N2 then decreased. 

Keywords: Hard coating, Magnetron sputtering, Microstructure, Nitride, PVD, Reactive gas, Steel, Thin films, Zr-N.