Inhibitive Effect of NO3- on the Corrosion Behavior of U-0.79wt%Ti Alloy in NaCl Solution

The inhibitive effect of NO3- on the corrosion behavior of U-0.79wt%Ti alloy in 0.01 mol/L NaCl solution was studied by electrochemical methods. The results show that NO3- ions possess inhibitive effect on the corrosion of U-0.79wt%Ti alloy in the solution containing Cl- ions, which has a close relationship with the concentration of NO3-. When the concentration ratio of NO3- and Cl- exceeds 0.1, NO3- could inhibit the appearance of the pitting on U-0.79 wt%Ti alloy effectively; however, when the ratio is less than 0.1, NO3- shows hardly any inhibitive effect on the corrosion behavior of U-0.79 wt%Ti alloy. In the viewpoint of electrochemical process, the NO3- could increase the open circuit potential (OCP) of the alloy and lower the concentration polarization; meanwhile, it could increase the limited diffusion current density. At the same time, NO3- could also lower the rate of active anode dissolution, and increase the pitting corrosion potential of U-0.79 wt%Ti alloy. The surface scratches experiments show that the inhibitive effect of NO3- may root from that the NO3- ions have precedence over Cl- ions in being absorbed at the surface defects, which would inhibit the nucleation of pitting corrosion.