SURFACE MODIFICATION OF TI-6A1-4V SURGICAL ALLOY BY PLASMA SOURCE ION-IMPLANTATION

Plasma source ion implantation (PSII) was applied to Ti-6Al-4V surgical alloy to improve its tribological properties. Nitrogen implantation at room temperature produced an improvement in wear resistance. Implantation at an elevated temperature (approximately 600-degrees-C) resulted in a substantially thicker modified surface layer with sustained wear resistance. The best results were obtained by a two-step process wherein elevated temperature implantation was followed by room temperature implantation. The tribological properties resulting from this two-step process surpassed those of the Co-Cr alloy and were comparable with those obtained by ion nitriding. The base material properties remained unchanged after the PSII treatments. The surface properties were characterized using low-load microhardness measurements, pin-on-disk wear testing and Auger spectroscopy.