Structure and morphology of Zr-O-N coatings formed by the method of cathodic arc evaporation

Oxynitrides of transitional metals are a coating material with decorative features due to the possibility of their adjustable colouring and good mechanical properties. The coatings of zirconium oxynitride have been deposited by the method of cathodic arc evaporation onto steel substrates. A set of coatings obtained at different relative volumetric concentrations of oxygen in the reaction atmosphere during deposition has been investigated. The influence of oxygen concentration on the colour, surface morphology and phase composition of the coatings has been analyzed. With the increase of oxygen content, the colour of the thin Zr-O-N coating has changed from golden-yellow to graphite. Observation of the surface of the coatings by means of the SEM method has shown the presence of surface defects in the form of macroparticles ranging from a submicron to several micrometers, with the smallest microparticle population being the largest. It has also been found that the surface roughness of the Zr-O-N coatings increases as the relative volumetric concentration of oxygen in the atmosphere during deposition increases. By means of X-ray diffraction analysis it has been shown that the zirconium oxide phase has occurred with a relative oxygen concentration of 50%, whereas below this value only the ZrN phase has been observed. The value of the parameter of the regular elementary cell of the Zr-O-N coatings increases as the relative concentration of oxygen in the atmosphere increases, while at the same time the intensity of the diffraction lines of the coatings decreases.