Tribocorrosion behavior of beta titanium alloys in physiological solutions containing synovial components

In this work, the tribocorrosion behavior of Ti-12.5Mo, Ti-13Nb-13Zr and Ti-29Nb-13Ta-4.6Zr beta titanium alloys which are candidate biomaterials for joint prostheses is studied against ultra high molecular weight polyethylene in Hank's balanced salt solution. Ti-6Al-4Fe alpha+beta titanium alloy is also tested for comparison. Experiments were carried out at open circuit potential and at a passive applied potential using a pin-on-flat reciprocating sliding tribo-electrochemical apparatus. The potential, anodic current and friction coefficient were measured in situ as a function of time. The beta alloys exhibited a tendency to repassivate during sliding at passive and open circuit potential. The predominant wear mechanism of the metal-polyethylene pairs was 3 body wear, exhibited by the transfer of polyethylene to all titanium alloys. Polyethylene showed a comparatively low wear against beta titanium alloys. The effect of the addition of synovial fluid constituents, namely bovine serum albumin, hyaluronic acid and dipalmitoyphosphatidylcholine on the tribocorrosion of Ti-29Nb-13Ta-4.6Zr alloy was also studied. The presence of additives affected the friction coefficient, induced an increase of the wear volume, and a modification of the dominant wear mechanism which was identified as abrasion without transfer of polyethylene. (C) 2010 Elsevier B.V. All rights reserved