Ru-induced microstructural change in ion-plated TiN coating and its tribological properties

TiN and Ti(Ru)N (3 wt%, Ru) coatings were deposited on Ti6Al4V substrate by arc ion plating method. Ti(Ru)N coating exhibits golden luster as the TiN coating does. From XRD, XPS and TEM investigations, Ru addition refines the TiN grains and Ti(Ru)N coating can be concluded as a kind of composite layer, which is mixed by Ru-containing amorphous part and crystalline TiN phases. The related hardening mechanism of Ru addition in TiN coating is fine grain strengthening. Wear resistance of Ti(Ru)N coating is significantly better than that of TiN coating, due to its higher hardness, higher H/E value and lower COF value. Improved wear performance of Ti(Ru)N coatings is mainly contributed to the mechanism of fine grain strengthening, which delays the occurrence of pitting of large-scale peel-off behavior like TiN coating.