Wear improvement of surgical titanium alloys by ion implantation

Abstract

Titanium based alloys are being considered as orthopaedic implants for a variety of reasons such as excellent corrosion resistance, high fatigue strength, low modulus of elasticity, and most importantly, excellent biocompatibility. The only questionable property of these alloys is their wear resistance. While Ti–6Al–4V has recently been introduced for construction of the femoral component in knee-joint systems, the questionable wear performance of the Ti–6Al–4V is a barrier for a more widespread acceptance of the alloy for this application. The ion implantation process as shown in this study is being considered as an effective method for improving the wear performance of titanium based alloys for orthopaedic implants. Ion beams of carbon and nitrogen have been used to implant the surface of Ti–6Al–4V hemispherical samples. The samples were tested in a pin-on-disk machine against ultrahigh molecular weight polyethylene (UHMWPE) with loads representative of total joint replacements. Deionized water and Ringer’s solution have been used as lubricants for the wear tests. The wear data of the UHMWPE and implanted samples are presented. The results show that the implantation process is effective in reducing the wear associated with the Ti–6Al–4V alloy used for prosthesis purposes.