Crevice corrosion calculation model

The potential and current distribution results from the computational modeling are shown in Fig. 20. The calculated x rit values (determined by locating the position at which the potential falls into the active region) are also shown. A comparison of the data from the crevice corrosion experiments and those predicted by the model is shown in Fig. 21. Figure 22 plots the same data, but with the ordinate axis is now in terms of... 

As the basic mechanisms of crevice corrosion have been understood to some extent, many models have been developed either to describe the steady state of an actively corroding crevice or to calculate the environment evolution and predict the passivity breakdown. These models are able to reproduce some major features of crevice corrosion, particularly geometric effects, but they all suffer from the lack of knowledge of the complex concentrated solutions that are formed in the crevice. 

An outstanding contribution has been made by Oldfield and Sutton [13]. They have developed a mathematical model of crevice corrosion in which observations, such as the fall in pH, localized breakdown of passive films and the onset of crevice corrosion in stainless steels, is presented. A summary of the model developed by Oldfield and Sutton is given below. For calculation and detailed discussion, reference must be made to the original paper. In the model developed, crevice corrosion is considered a four stage mechanism. The four stages of crevice corrosion suggested are shown in Fig. 4.18. 

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