Crevice corrosion mathematical model

A numerical model of crevice corrosion. Many mathematical models have been developed to simulate processes such as the initiation and propagation of crevice corrosion as a function of external electrolyte composition and potential. Such models are deemed to be quite important for predicting the behavior of otherwise benign situations that can progress into aggravating corrosion processes. One such model was published recently with a review of earher efforts to model crevice corrosion. The model presented in that paper was appHed to several experimental data... 

In recent years the mechanism of crevice has been mathematically modelled and a more thorough understanding of the corrosion processes has been evolved . From such mathematical modelling it is feasible to predict critical crevice dimensions to avoid crevice corrosion determined with relatively simple electrochemical measurements on any particular stainless steel. 

Walton, J. C., Mathematical Modeling of Mass Transport and Chemical Reaction in Crevice and Pitting Corrosion, Corrosion Science, Vol. 30, No. 8/9, 1990, pp. 915-928. 

Despite the several mathematical models being developed for describing corrosion problems and their solutions, each model has its own degree of accuracy, which depends on the chosen variables and conditions, and numerical method for determining relevant parameters that describe a particular corrosion phenomenon. Comprehensive reviews of models for describing a particular problem, such as crevice cathodic protection, pitting growth rate, current and potential attenuation are available in the literature [2,3,18,25-32]. 

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. 

---