AbstractIn the present work, the effects of dissolved oxygen and hydrogen peroxide on corrosion potential have been studied on type 316L stainless steel in a hot lithium hydroxide solution. The results indicate that the corrosion potential will remain at around −850 mV vs SCE if the dissolved oxygen in the solution is controlled at a level of less than 10 ppb. However, 316L stainless steel will become completely passivated when about 650 ppb of oxygen exists in the solution. As a result, the corrosion potential of 316L steel will rise to around −400 mV vs SCE, and eventually, with longer immersion times, to even higher values, e.g. −300 mV vs SCE. However, the presence of less than 500 ppb H2O2 has no significant effect on the corrosion potential. A potential jump (from −850 to −500 mV vs SCE) is observed only when a large amount of H2O2, for instance 1 ppm, is present in the solution. Related to radiolysis of water and with potential-dependent stress corrosion cracking, the effects of dissolved oxygen and hydrogen peroxide on the corrosion potential of 316L stainless steel in the hot lithium hydroxide solution have been discussed.
本研究では、高温水酸化リチウム溶液中における316Lステンレス鋼の腐食電位に及ぼす溶存酸素と過酸化水素の影響について検討した。結果によれば、溶液中の溶存酸素濃度を10 ppb未満に制御した場合、腐食電位は約−850 mV（SCE基準）に維持される。しかし、溶液中に約650 ppbの酸素が存在すると、316Lステンレス鋼は完全に不動態化し、その結果、腐食電位は約−400 mV（SCE基準）まで上昇し、さらに浸漬時間が長くなると、最終的には−300 mV（SCE基準）程度のさらに高い値に達する。一方、500 ppb未満のH₂O₂の存在は腐食電位に有意な影響を及ぼさない。電位の跳躍（−850 mVから−400 mV（SCE基準）へ）は、溶液中に例えば1 ppmといった多量のH₂O₂が存在する場合にのみ観察される。水の放射線分解および応力腐食割れの電位依存性に関連して、高温水酸化リチウム溶液中における316Lステンレス鋼の腐食電位に及ぼす溶存酸素と過酸化水素の影響について考察した。