Tribocorrosion behaviors of superhard yet tough Ti-C-N ceramic coatings

Ceramic materials are widely used as protective coatings for marine engineering components in seawater environments due to their high wear and corrosion resistance. However, the applications and lifetimes of these materials have been always limited by the high brittleness of ceramic coatings. Hence, in this work, we report superhard yet tough Ti-C-N coatings with mixed TiC and TiN phases deposited by reactive high power impulse magnetron sputtering. Ti-C-N coatings exhibit a simultaneous superhardness of 40.2 GPa and favorable toughness due to fully dense microstructure and smooth surface morphology. These superhard yet tough Ti-C-N coatings show excellent seawater-lubricating behaviors with an extremely low friction coefficient of 0.03 and mild wear track in 3.5 wt% NaCl aqueous solution. The enhanced tribocorrosion performance is attributed to the increased resistance to crack initiation and propagation, restraining the synergistic actions of wear and pitting corrosion.