Structure and Properties of ZrON Coatings Synthesized by Cathodic Arc Evaporation

The transition metal oxynitrides are a coating material with decorative features due to their adjustable color and good mechanical properties. The purpose of the research was to study the effect of the relative oxygen concentration O-2(x) = O-2/(N-2 + O-2) in particular on adhesion, but also on the color, structural and mechanical properties of ZrON coatings synthesized by cathodic arc evaporation on HS6-5-2 steel substrates. The surface morphology, phase and chemical composition and mechanical properties were determined using scanning electron microscopy, X-ray diffraction, wavelength dispersive X-ray spectroscopy, nanoindentation and scratch test. It was found that color of the coatings changed from light yellow for ZrN first to gold and then to graphite for Zr-O phase with increase of oxygen concentration. X-ray diffraction patterns showed that the phase separation of ZrN and ZrO2 occurred for about 35 at.% of oxygen in the coating. Increase in oxygen concentration in the coatings led to decrease in crystallite size from about 20 nm for ZrN to about 5 nm for coatings with about 35 at.% of oxygen and about 25 at.% of nitrogen. An increase in hardness from about 26 GPa for ZrN to about 30 GPa for coating with small concentration of oxygen (about 9 at.%) and then decrease to about 15 GPa was observed. Adhesion of Zr-O-N coatings demonstrated strong dependence on oxygen concentration. Critical load for ZrN is about 80 N and decreases with oxygen concentration increase to about 30 N for ZrO2.

Automated summary

The research investigated the influence of oxygen concentration on the adhesion, color, structure, and mechanical properties of transition metal oxynitride ZrON coatings. The results revealed changes in color, crystallite size, and hardness with increasing oxygen concentration, while adhesion showed a strong dependence on the oxygen concentration.