Real-Time Monitoring of Crevice Corrosion Propagation Rates in Simulated Seawater Using Coupled Multielectrode Array Sensors

Abstract Real-time coupled multielectrode array sensor probes were used to measure the localized corrosion rates for Type 1008 carbon steel, Type 110 copper, and Type 316L stainless steel in simulated seawater under creviced and exposed conditions. The maximum localized corrosion rate, for the carbon steel probes measured under a crevice, was 10 to 25 times lower than that measured under exposed conditions; the localized corrosion inside the crevice was found to be in the form of pitting corrosion. The maximum localized corrosion rate for the stainless steel probes was similar to that measured without a crevice. The similarity of the localized corrosion behavior, with and without a crevice for the stainless steel probes, was attributed to the relatively large gap of crevice (0.089 mm) that was not tight enough to have a significant effect on the corrosion. An exposed large electrode, made from the same wire as that of the carbon steel probe electrodes, was placed near the probes and in the same solution, in order to simulate the metal surrounding a creviced area. The corrosion potential of the creviced probe was found to be higher than that of the exposed large metal electrode. When the creviced probe was coupled to the large metal electrodes in the simulated seawater, its corrosion rate decreased essentially to zero, and the sensing electrodes of the creviced probe were cathodically protected by the exposed large electrode.