Corrosion behaviour of Ti40Cu60 alloy in H3PO4 solutions

The electrochemical behaviour of Ti40Cu60 alloy has been investigated in aerated H3PO4 (0.5–4.5 M), at 37 °C by means of electrochemical impedance spectroscopy, potentiodynamic polarization, galvanostatic polarization and Mott–Schottky techniques. The passivation of the sample has been discussed in term of time constant RC, in particular. The highest value of time constant (355.3 ms) has been obtained after potentiodynamic polarization in 1 M H3PO4; at this same concentration, passivation and corrosion currents are the weakest. On the other hand, in 0.5 M the time constant has the weakest value (251.2 ms); this result is in good agreement with chronopotentiometry curve which indicates a weak dissolution of the passive film at the beginning of the galvanostatic polarization and with potentiodynamic polarization which reveals the highest passivation plateau at this concentration. The Mott–Schottky technique performed in 1 M H3PO4 and 10 Hz shows that the passive film has a semi-conductor character of n-type.