Corrosion behavior of new titanium alloys for medical applications

Abstract

In this study, the ability of two titanium alloys to resist corrosion has been analyzed. This was accomplished by analyzing how the corrosion potential evolves with time as well as observing the Bode and Nyquist diagrams obtained with electrochemical impedance spectroscopy. The proportions of each alloy were A1 (94.4 % Ti, 4 % Mn, 0.6 % Al, 1 % Fe) and A2 (96.5 % Ti, 3 % Mn, 0.6 % Al, 0.2 % V). The two samples were covered in epoxy resin, cut in pieces, and polished using silicon carbide sheets of abrasive paper, the polishing was done progressively, using gradings from 280 to 1200 grit, ultimately using a 0.1 alpha alumina suspension for a last polish. Electrochemical tests were performed by immersing the polished samples in a Ringer Lactate solution. While the samples were immersed, they were connected to a saturated calomel electrode as reference electrode and to a platinum electrode acting as counter electrode. The two materials can resist to the effects of corrosion efficiently; initially it seemed that the alloy A1 improves its capacity to resist at corrosion when a positive potential is applied and loses it partially when a negative potential is applied. In alloy A2 the situation was similar but easier to observe, as when the supplied potential was too high or too low, the passivation of the material was not so good.