Journal of Materials Science, Vol.32, No.16, 4355-4376, 1997
Behavior of 316 Ti Stainless-Steel in Deuterium-Oxide with Chloride
Since tritiated water contains deuterium oxide, we require a better understanding of stainless steel corrosion in tritiated water and thus we have compared the behaviour of 316 Ti stainless steel in (H2O)-H-2 and H2O with and without chloride. This was done by anodic polarization curves, cyclic voltammetry and electrochemical impedance spectroscopy. The corrosion potential of 316 Ti stainless Steel in deuterium oxide changes and is related to pH modification due to the dissociation constant of this aqueous medium which shows the importance of pH in passivity. Without chloride, the insulating properties of the passive oxide layer depending on the pH and passive potentials are enhanced with (H2O)-H-2. With deuterium oxide containing chloride at near neutral pH, the repassive potential is lower than that obtained with H2O, consequently localized corrosion in grain boundaries and pit propagation, which lead to crevice corrosion, are greater. The critical pitting potential is in transpassivity indicating that pitting is less likely to occur. Comparison with and without Cl- for the passive potentials near the corrosion potential, shows that although chloride reduces the insulation provided by the passive oxide layer it is still greater than that obtained with H2O.