Tribological performance of Ti-6Al-4V plasma-based ion implanted with nitrogen

A low-temperature (<180°C) plasma-based ion implantation (PBII) with nitrogen that did not affect structure and surface morphology of the substrate barely changed the sample dimension. The hardness increasing factor increased with an increase in implantation dose and/or increase in implantation energy, reaching 1.4–1.7 at the lowest plastic penetration of nearly 300 nm. Wear resistance increased greatly after implantation, and increased with decrease in sliding speed. Friction coefficient decreased, and wear resistance increased with an increase in implantation dose and/or energy or when the counterbody AISI 52100 was replaced with Ti-6Al-4V when treated in the same manner as the disc. Both wear of the unimplanted and implanted discs are abrasive-dominated. A tribofilm, mainly made up of wear debris which was transferred from the disc wear-surface formed the wear surface of the counterbody. The observed wear weight increase of the counterbody (Ti-6Al-4V same treated as the disc) with wear cycle could be the result of the transferred wear debris or tribofilm. The formation and transition of tribofilm during the wear process (the morphology, distribution of the wear debris transferred and the adhesion between the tribofilm and the underlying ball wear surface) are important to the tribological properties and wear mechanism of the implanted samples.