Corrosion of carbon steel has been investigated for 200 h in concentrated aqueous solution of mixed LiBr-LiNO_3-KCl-LiOH salts at elevated temperatures as functions of temperature and concentration of LiNO_3 and Li_2MoO_4O. The structure and composition of the surface films were analyzed by XRD, SEM and XPS. At 463 K, addition of LiNO_3 (>0.0125 mol/kg) decreased the total amount of iron corroded (W_T), amount of iron ions in the oxide (W_F) and amount of Fe~(2+) ions dissolved into the water (W_D) drastically, however pits were observed. At LiNO_3=3.01 mol/kg, W_T and W_F increased as temperature rises, whereas W_D decreased as temperature rises.Pit was observed at LiNO_3=3.01 mol/kg between 363 K and 463 K. Below 403 K, pit depth was less than 15 #mu#m, while above 433 K the pit depth was more than 80 #mu#m. These corrosion behavior did not depend on the addition of Li_2MoO_4. Outermost parts of oxide films formed at LiNO_3=3.01 mol/kg, were composed of #gamma#-Fe_2O_3 and the decrease in the LiNO_3 concentration changed the composition from #gamma#-Fe_2O_3 to Fe_3O_4. The role of surface film in the corrosion behavior was discussed in terms of its ion-selectivity and OH~- ion stabilizing ability.
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