Tafel numerical simulation

Most electrode reactions encountered in the field of corrosion involve the transfer of more than one electron. Such reactions take place in steps, of which the slowest, called the rate-determining step, abbreviated RDS, determines the overall reaction rate. In simple cases, one can identify the rate-determining step by an analysis of the measured Tafel slopes. In the so-called quasi-equilibrium approach one assumes that with the exception of the rate-limiting step, all other steps are at equilibrium. This greatly simplifies the mathematical equations for the reaction rate. More realistic approaches require numerical simulation and shall not be discussed here. To illustrate the quasi equilibrium approach to the study of multi-step electrode reactions we shall look at proposed mechanisms for the dissolution of copper and of iron. 

The results of the error analysis can be expressed in terms of two dimensionless parameters (I corrA/ and bjbc) using numerical simulation. The computed errors are actually a function of three parameters /corrA/ and b - However, the ratio b jb can be used, to a very good approximation, in place of b and b because the effect of the Tafel slopes is opposite and almost equal, as discussed below. Consequently, the error mainly depends on the ratio of the Tafel slopes, while it depends only slightly on the... 

This error was investigated by the numerical simulation technique. The error increases with increasing RsIRp ratio and with increasing Tafel-slope ratio ( >iarge/ smaii)- However, the error... 

This error was also investigated by the numerical simulation technique. The error increases with increasing Rs/Rp ratio and with increasing Tafel-slope ratio ( >iarge/ smaii) The error also depends slightly on the individual Tafel slope values, but this introduces only an uncertainty of 20% (relative) of the representation given in Fig. 15. This technique, as well as the three-point technique, is more sensitive to the solution resistance than the... 

We have remarked earlier that the treatment given above is based on an assumption for the case of that is, they are in an effective parallel combination. This is not strictly correct for a number of conditions, so the logarithmic potential-decay slopes in relation to Tafel slopes must be worked out from the full kinetic equations of Harrington and Conway (104) referred to earlier, based on the relevant mechanism of the electrode reaction. Numerical solution procedures, using computer simulation calculations, are then usually necessary for comparison with observed experimental behavior. 

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