Effect of surface modified layers on fretting fatigue damage of biomedical titanium alloys

Abstract

Fretting fatigue is a typical wear phenomena effecting from conjoint action of fretting and cyclic load under fixed contact pressure. The aim of the present work is to investigate the effect of surface modification processes such as plasma nitriding, ion implantation and laser nitriding in preventing fretting fatigue failures of Ti–6Al–4V and Ti–6Al–7Nb contact pairs. Surface modified contact pads and calibrated proof ring was used to apply contact pressure normal to the fatigue specimen. The surface modified layers and fretting fatigue damage is shown with optical and SEM micrographs. Friction coefficient between fretting contacts is continuously recorded to explain the sequence of damage during fretting process. Plasma nitrided pairs have performed better than all other processes with minimal damage and low friction (0·1). The facture of ion implanted pairs was similar to that of unmodified alloys. Laser nitrided pairs have shown premature failure owing to higher case depth.