Lorenz and Heusler

The initial Tafel lines for iron anodic dissolution and cathodic deposition have been measured starting from various steady states. They all intersected at the equilibrium potential of the iron electrode, leading to a set of initial current densities. In view of this behavior, Lorenz and Heusler concluded that initial reaction orders, with respect to, for example, hydroxyl ions, derived from measurements of initial polarization curves have no meaning. Nevertheless, other opinions can be offered. If, for example, one considers that the equilibrium reaction Fe + 2e <=> Fe occurs at specific sites k, the intersection at = of the initial... 

Some authors found transition times of the order of tenths of a second, independent of the starting potential, polarization, and the pH value, but dependent on the temperature. " According to Lorenz and Heusler, " longer times of many minutes were correlated with the time necessary to establish a steady-state morphology. 

W. J. Lorenz and K. E. Heusler, Anodic dissolution of iron gronp metals, Corrosion Mechanisms (F. Mansfeld, ed.), Marcel Dekker, New York, 1987. 

According to Heusler and co-workers, Lorenz and co-workers, " and also Vojnovic, alkali perchlorates or sulfates are almost inert electroytes that is, neither their cations nor their anions influence the dissolution process significantly. Nevertheless, adsorption of sulfate ion on iron from sodium sulfate solutions at open-circuit potential was measured by Hackerman and Stephens. ... 

The next iterative analysis of the influence of adsorbed hydrogen on the iron dissolution kinetics included the possible correlation between the surface structure and the reactions occurring at specific sites, as revealed by experimental and theoretical studies by Allgaier and Heusler, " Lorenz and co-workers, and Keddam andco-workers. " All these authors agreed that the dissolution rate constant should be proportional to the weakness of the binding of the surface atoms to the bulk metal, thus decreasing in the order kink > step > plane. The rate of metal dissolution is proportional to the rate constant and to the number of atoms in the position concerned, which decreases in the order plane > step > kink. 

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