Improvement of the wear behaviour of the couple UHMWPE–Ti6A14V through surface treatments

Owing to the great interest in the medical field in the tribological couple UHMWPE–Ti6Al4V, its wear behaviour was studied and compared to that displayed by the more typical couples of UHMWPE–AISI 316 and UHMWPE–Vitallium. The Ti6Al4V alloy was given three different surface treatments: (a) a conventional lapping procedure; (b) a special lapping procedure; (c) nitrogen ion-implantation at 873°K. The last two samples induced, on a UHMWPE countetace, a wear rate lower than a factor of 10 compared to diamond lapped specimens; their behaviour was also better than the couples UHMWPE–AISI and UHMWPE–Vitallium. Wear improvement was attributed to the reduction of polymer transfer and adhesion on the metal counterface, due to the reduction of adhesive affinity between UHMWPE and the metal following surface treatment of the metal. The results are interpreted on the grounds of TEM and AES analyses.