溶融Li₂CO₃-Na₂CO₃共晶塩中におけるステンレス鋼の低温腐食とその対策

抄録

The effect of temperature and gas atmosphere on corrosion behavior of type 316L stainless steel in a molten Li₂CO₃-Na₂CO₃ eutectic has been investigated. When the CO₂ partial pressure was higher than 0.02 atm and the temperature was lower than 843K, the severe corrosion (localized corrosion) occurred. However, once the sample had been kept for some periods in the melt under N₂ (or N₂+5%H₂O), no severe corrosion occurred, even though the atmosphere shifted to the localized corrosion condition subsequently. From this result, it was revealed that localized corrosion was avoidable by forming LiFeO₂ layer on the metal surface in advance. Especially, the addition of H₂O into the atmosphere could become effective method to prevent localized corrosion.