Corrosion behavior of stainless steel in molten Li2CO3-Na2CO3 eutectic

The corrosion behavior of type 316 L stainless steel in a molten Li2CO3-Na2CO3 eutectic had been investigated using electrochemical methods in the temperature range of 823 K-973 K. The anodic polarization curve of 316 L showed the passive behavior at 923 K. The anodic current density of 316 L increased with temperature in Ar or Ar+30%CO2 from 923 K to 973 K. On the other hand, the transition of the active-passive behavior in the polarization curve did not appear in Ar+30%CO2 at 823 K, and a lot of corrosion pits were observed on the surface after the test. This anomalous corrosion (so-called hot corrosion) of 316 L at 823 K seems to be caused by the instability of the outer scale under the CO2 contained atmosphere, and by the difficulty in forming the continuous inner oxide scale at low temperature.