Inhibition of tribo-oxidation preceding wear, by single-phased TiNx films formed by ion implantation into TiAl6V4

Abstract

Single-phased films of α-Ti1−x Nx, ∊-Ti2Nx, or δ-TiNx with a homogeneous composition on more than 400 nm were produced by ion implantation at several different energies in the TiAl6V4 alloy. Secondary ion mass spectroscopy (SIMS) profiles and ionic images recorded within the tracks after incremented cycles of friction against a 35NCD16 steel ball in air have shown that a Ti–O–C–N film is progressively formed on the surface of α solid solutions, while more concentrated nitride films resist oxidation. The friction and abrasion resistances of ∊ or δ nitride films are initially improved for a time lasting for as long as their N content increases, but they are finally self-destroying. On the contrary, the hardening effect of N in an α-Ti matrix keeps a really severe amount of abrasion from occurring during running in of the implanted surface, without suppressing the building up of a lubricant oxide hardened by N.