Hardness and tribology measurements on ZrN coatings deposited by reactive sputtering technique

ZrN coatings have been grown in an rf sputtering deposition chamber, using different ratios of Ar/N2 (5/1, 5/5, 1/5) in the reactive gas flow. After deposition, the coatings were thermally treated in a 500 °C oxygen atmosphere, in order to test the thermal stability of the layers or the oxynitride formation. The chemical composition, surface roughness and structural, mechanical and tribological properties of the as-deposited and annealed samples have been measured by energy dispersive spectroscopy (EDS), atomic force microscopy (AFM), X-ray diffractometry, nanoindentation and pin-on-disk techniques, respectively. Deposition parameters determine the growth rate, crystalline structure and surface roughness, which affect the mechanical and tribological behaviour of the samples. The best mechanical and tribological performance and highest growth rate was found for the sample grown under 5 sccm Ar+1 sccm N2 gas flow. The as-deposited layers have a low wear, showing an increase in hardness after annealing making them suitable as protective layers.