Electrochemical effects on the fretting corrosion behaviour of Ti6Al4V in 0.9% sodium chloride solution

The fretting corrosion behaviour of a Ti6Al4V alloy in contact with an alumina ball was investigated in a 0.9% sodium chloride solution. The tests were carried out using a fretting test rig equipped with an electrochemical cell. The effects of applied potential and oscillation frequency were evaluated for micro-motions of 50 and 100 μm amplitude. Scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) techniques were used to characterise the worn surfaces. Results were interpreted using the third body and the dissipated energy approaches. The extent of wear was profoundly affected by the applied potential, especially for potentials above approximately −0.2 V Ag/AgCl. This effect was related to the increasing oxidation of the third body formed by plastic deformation of the metal found at higher anodic potentials. On the other hand, the mechanical energy necessary for wear was found to be dramatically decreased when anodic potentials are applied.