Tribocorrosion behavior of β 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 β titanium alloys which are candidate biomaterials for joint prostheses is studied against ultra high molecular weight polyethylene in Hankʹs balanced salt solution. Ti–6Al–4Fe α + β 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 β 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 β 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.