Improving the hardness of high entropy nitride (Cr0.35Al0.25Nb0.12Si0.08V0.20)N coatings via tuning substrate temperature and bias for anti-wear applications

The high entropy nitride coatings (Cr0.35Al0.25Nb0.12Si0.08V0.20)N with high hardness of 35 GPa and a high H-3/E-2 of 0.52 were fabricated by RF magnetron sputtering system via tuning the processing parameters, such as substrate temperature and bias. The chemical composition, crystal structure, grain size, and residual stress were measured and analyzed to determine the mechanisms of hardness improvement. The crystal structure maintained B1 face-center cubic structure throughout all the conditions. The hardness was improved from 28 GPa to 35 GPa by sputtering at 300 degrees C with -150 V bias. Such hardness was achieved due to increased densification and compressive residual stress. Furthermore, the wear test of high hardness and high value of H-3/E-2 coatings were performed at both ambient temperature and 600 degrees C. The correlation among H-3/E-2, oxidation resistance, and wear rate was addressed and discussed.