Steady State Film Growth on Passive Iron in Neutral Solutions

Abstract

AbstractThe steady state growth kinetics of the oxide film on passive iron in neutral solutions was studied by galvanostatic and potentiostatic techniques. There is a good correlation of results obtained at constant c. d. and at constant potential. The experimental expressions relating to potential, layer thickness and oxidation rate make it clear that the steady state kinetic follows the classical Frenkel equation. The constants appearing in this equation were determined and compared with existing data. The temperature dependences of the passive film conductivity and of the field coefficient are also in accord with the mechanism of field assisted ionic transport over a potential barrier, as expressed by the classical rate equation.