Effects of potential on the electrical conductivity of a solution within a crevice of stainless steel in high-temperature water

Soma, Yasutaka   ; Komatsu, Atsushi ; Kato, Chiaki   

This study investigates the effects of potential (electrochemical corrosion potential (ECP)) on the water chemistry within a crevice of stainless steel in 288C water containing Clmajor anionic impurities. In situ measurements of the electrical conductivity of a solution within a 15 m gap crevice () were conducted using small sensors installed at different crevice depths. The ECP at the external surface of the crevice specimen (Eext) was controlled by the dissolved oxygen concentration in the bulk water. An increase in Eext from approximately -0.49 V (versus a standard hydrogen electrode at 288C) to -0.12 V resulted in an increase in from 12 to 160.3S/cm at 21 mm from the crevice mouth. FEM analysis taking into account the electrochemical reaction quantitatively reproduced this behavior. Cl was considered to be the major anionic species transported into the crevice in this potential range. A further increase in Eext up to 0.3 V led to a decline in . An increase in the flux of oxidizing (O and hydrochromate ion) and alkalizing species (OH) into the crevice was considered the cause of this behavior.