Influence of Nb and Ta on the corrosion and mechanical properties of CrYN coatings

Barrier coatings are applied to many machine components that are exposed to aggressive/harsh service conditions to prevent corrosion, oxidation, and wear at high temperatures. These coatings are widely used to protect structural components of gas/steam turbines in the energy and aerospace industries against aggressive operating conditions. In this study, Nb and Ta-doped CrYN films were deposited onto 316L stainless steel (SS) using the CFUBMS (Closed Field Unbalanced Magnetron Sputtering) technique. Then, the corrosion resistance, and structural and mechanical properties of the CrYN:Nb/Ta thin films were investigated. SEM, XPS, EDS, nanoindentation and potentiostat tester were used to determine the structural, mechanical and corrosion properties of the thin films, respectively. The highest hardness was found to be 21.4 GPa for CrYN:Nb films and 18.2 GPa for CrYN:Ta films. The results show that the coated specimens (lowest Icorr value 4 nA obtained in all tests) have higher corrosion resistance than the uncoated specimens (substrate Icorr value 1826 nA). In addition, it has been observed that the corrosion resistance of Ta-doped CrYN thin films is somewhat better than the niobium-doped thin films.