| Seawater has been used for a range of industrial activities such as transport, exploration of natural resources, etc. Sea water is a highly corrosive environment and is still a challenge to corrosion experts. Even though some materials exhibit good resistance to uniform corrosion, they are highly susceptible to a form of corrosion termed as crevice or hidden corrosion. Crevice corrosion is a localized attack that occurs at narrow spaces such as O-ring or flanges in cooling water piping networks. Reliable prediction and mitigation of crevice corrosion in cooling water piping of submarines is a longstanding problem for the Navy. Such reliability requires accurate strategies for efficient sensing and mitigation.;The difficulty in probing crevice corrosion is that the geometries are exceedingly tight and the insertion of electrically or chemically sensitive probes can influence the corrosion process. This thesis reports experimental studies using embedded electrodes within O-rings for both sensing and mitigating crevice corrosion. A mathematical model is developed to understand both the corrosion initiation conditions and the efficiency of the mitigation strategy.;Electrochemical Impedance Spectroscopy was used to monitor the impedance of the crevice surface. Crevice corrosion mitigation experiments were conducted by using impressed currents via an embedded electrode for S.S. 316 plates in two electrolyte systems, 3.5 wt% NaCl and 1 wt% FeCl3. The results showed that application of a few of micro-amperes of currents were enough to mitigate the crevice corrosion. The numerical modeling of polarization behavior inside crevices indicated that the anodic polarization within high aspect ratio (>5) crevices could exceed tens to hundreds of mV in a day depending upon the crevice mouth potentials. The observed decrease of non-dimensional metal dissolution rate and potential when currents are applied indicate that the corrosion propagation is slowed down. |
