Microstructure and tribocorrosion properties of TiZrNbTaFe, TiZrNbTaFeC, and TiZrNbTaFeCN high entropy alloy coatings

High entropy alloy (HEA) coatings have emerged as a promising solution for various industrial applications due to their exceptional mechanical properties and corrosion resistance. In this study, three TiZrNbTaFe (HEA), TiZrNbTaFeC with 2.5 at% C (HEAC), TiZrNbTaFeCN with 7.3 at% C and 40.3 at% N (HEACN) coatings were prepared, respectively, using a superimposed high power impulse magnetron sputtering and medium-frequency sputtering systems. The HEA and HEAC coatings exhibited amorphous structures, while the HEACN coating had an FCC crystal structure. In pure corrosion tests in 3.5 % NaCl solution, the HEAC coating showed superior corrosion resistance, which is 25.6 times greater than 304SS substrate. A pin-on-disk tribometer with a 1 N load, integrated with a potentiostat, was used for tribocorrosion testing in a 3.5 % NaCl solution. HEAC coating exhibited lower coefficient of friction values of 0.33 and 0.24 under dry wear and tribocorrosion test due to its carbon-induced lubricating effect. HEACN coating presented a lower wear rate in wear and tribocorrosion tests because of its higher hardness of 21.4 GPa. The HEACN coating showed the best tribocorrosion resistance, with the lowest total loss of 17.1 mm/yr. The HEAC coating performed better, with a total loss of 25.5 mm/yr. The HEA coating had the highest total loss due to its high pure wear loss. The synergistic components were 15.2 mm/yr for HEA, 14.4 mm/yr for HEAC, and 12.5 mm/yr for HEACN. We can conclude that corrosion plays a stronger role in the synergistic wear-corrosion damage of TiZrNbTaFe-based HEA, HEAC, and HEACN coating.