In Situ Electrochemical Study on Crevice Environment of Stainless Steel in High Temperature Water

In situ electrochemical impedance spectroscopy measurement within crevice of stainless steel in 288 °C water has been conducted to analyze crevice water chemistry. Small sensors ($$ {\varphi} {\sim} 250\,\upmu{\text{m}}) $$ measured local solution electrical conductivity κ_crev, polarization resistance and electrochemical corrosion potential. Real-time response of the κ_crev as functions of bulk water conductivity and dissolved oxygen (DO) concentration has been quantitatively analyzed. The κ_crev differ more than an order of magnitude depending on the oxygen potential inside the crevice. The κ_crev increased with addition of small amount of bulk DO (e.g. 30 ppb). The maximum κ_crev was observed with DO of 32,000 ppb and became more than 100 times higher than that of bulk water. The effect of geometrical factors on the crevice environment was also found to play an important role in the water chemistry inside.