Properties of niobium nitride coatings deposited by cathodic arc physical vapor deposition

Thin films of niobium nitride were deposited on high speed steel substrate by cathodic arc physical vapor deposition using − 150 V, − 200 V and − 250 V bias voltages at 1 Pa nitrogen pressure. X-ray diffraction data showed that hexagonal δ-niobium nitride was formed for all bias voltages. Fracture cross-sections revealed the existence of the transition zone structure in all coatings. The maximum hardness was found to be 39 GPa. The Rockwell C adhesion and the scratch test were used to compare adhesion properties. In Rockwell adhesion test the best adhesion was obtained at − 150 V bias voltage and in scratch test the cracks were occurred approximately at 3–5 Ns.