Wear resistant and anti-corrosive treatment for TI-6AL-4V using metal vapor vacuum arc source in comparison with plasma immersion ion implantation

This study utilizes two ion-implantation methods, plasma immersion ion implantation (PIII) and metal vapor vacuum arc (MeVVA), to prepare Ti-N phases on the surface of Ti-6Al-4V. By the nitrogen PIII method, both nitrogen and minor oxygen species are simultaneously attracted by the negatively charged substrate. The penetration of N and O interstitial elements to an extensible depth is possible owing to the effect from the negatively charged target. The nitrogen PIII treatment does not produce a novel Ti-N phase. As a result, the modified surface does not behave anticorrosive. The H_n and the E determined by nanoindentation also remain unchanged. It is still potential to apply this non-directional treatment by increasing bias voltage of the target, coating pure titanium on Ti-6Al-4V, and adjusting the regeneration process of nitrogen ions. The MeVVA treatment creates a novel αTiN_0.3 (011) phase on Ti-6Al-4V in present study. It signifies that the interactions between kinetic Ti ions of varied energies and minor nitrogen molecules, with minor participation of oxygen, are highly feasible. The novel ion-implanted Ti-N phase is corrosion resistant, which is capable to reduce passivation current density by forming a passive film. Moreover, the MeVVA-treated surface is surface-hardened; the E is simultaneously increased. The increase of nano mechanical properties can be visualized by 3D images using Nano Vision and determined by analyzing the tip/surface impact structure on the indentation site.