Bonding Characteristics and Chemical Inertness of Zr–Si–N Coatings with a High Si Content in Glass Molding

High-Si-content transition metal nitride coatings, which exhibited an X-ray amorphous phase, were proposed as protective coatings on glass molding dies. In a previous study, the Zr–Si–N coatings with Si contents of 24–30 at.% exhibited the hardness of Si₃N₄, which was higher than those of the middle-Si-content (19 at.%) coatings. In this study, the bonding characteristics of the constituent elements of Zr–Si–N coatings were evaluated through X-ray photoelectron spectroscopy. Results indicated that the Zr 3d_5/2 levels were 179.14–180.22 and 180.75–181.61 eV for the Zr–N bonds in ZrN and Zr₃N₄ compounds, respectively. Moreover, the percentage of Zr–N bond in the Zr₃N₄ compound increased with increasing Si content in the Zr–Si–N coatings. The Zr–N bond of Zr₃N₄ dominated when the Si content was >24 at.%. Therefore, high Si content can stabilize the Zr–N compound in the M₃N₄ bonding structure. Furthermore, the thermal stability and chemical inertness of Zr–Si–N coatings were evaluated by conducting thermal cycle annealing at 270 °C and 600 °C in a 15-ppm O₂–N₂ atmosphere. The results indicated that a Zr₂₂Si₂₉N₄₉/Ti/WC assembly was suitable as a protective coating against SiO₂–B₂O₃–BaO-based glass for 450 thermal cycles.