Investigation on the Corrosion Resistance of T4C Titanium Alloy in Simulated Oilfield Solution

Based on the corrosion rates under high-temperature and high-pressure, both the corrosion behaviors of TC4 titanium alloy tubes in neutral and acidic (containing CO 2 and H 2 S) environments and the thermodynamic stability of their passivation films were investigated by in-situ electrochemical tests combined with molecular dynamics simulations and first-principles calculations. The results show that the corrosion of TC4 titanium alloy at 180 ℃ is mild. And the corrosion reaction of TC4 titanium alloy in different environments is controlled by an anodic reaction process. Comparing with the neutral environment, TC4 titanium alloy in CO 2 and H 2 S environment present smaller electrochemical corrosion kinetic resistance. Among three environments, TC4 titanium alloy shows the worst corrosion resistance in H 2 S environment. Cl - , HCO 3- and HS - , all have strong charge interactions with the positive-charged Ti atoms of TiO 2 (110) passivation surface. By altering Cl - concentration and temperature, the existence of H 2 S and CO 2 will reduce the binding energy between Cl - and TiO 2 (110) surface, i.e., the thermodynamic stability of the TiO 2 passivation film became worse.