Studies on the construction parameter of an artificial occluded cell for in-situ inspection of the propagation rate of localized corrosion

An artificial localized corrosion system is assembled and some parameters r elated to the localized corrosion in active dissolution state (i.e., non-pa ssive state) have been studied. The results showed that the developed elect rochemical system can satisfactorily imitate a naturally formed localized c orrosion and the coupling current can indicate the maximum localized propag ating rate. In this artificial system, the anodic dissolution reaction foll owed the auto-catalytic mechanism. The localized corrosion current density was dependent on the area ratio R of the cathode to the occluded anode. Whi le R was equal to or more than 6, the coupling current reached at a maximum value and did not alter with the increase in R-value. Therefore, R=7 is ch osen as one of these optimum parameters used in constructing the system, wi th which the biggest galvanic current might be obtained. In contrast, the t hickness of the polymer filler separating the occluded anode area from the bulk electrolyte solution and the volume of the occluded anode area did not affect the corrosion current obviously. They might affect the response tim e to approach a steady state.