The Effect of Sorbed Hydrogen on the Kinetics of Active Dissolution of Iron
A. I. Marshakov, A. A. Rybkina, and T. A. Nenasheva
Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia
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Received November 8, 2005
Abstract — The effect of hydrogen adsorbed or absorbed by iron (0.009% C) on the iron dissolution is studied on a bipolar electrode-membrane in 0.5 M S
solutions (pH 1.30) by cyclic potential pulses. Expressions that allow one to calculate the hydrogen coverage on the iron surface (
) as a function of the potential variation in a cyclic stepwise manner and also the hydrogen concentration in the near-surface metal layer (C) as a func-tion of variations in the intensity of the diffusion flow of hydrogen atoms in the membrane are given. The method of cyclic potential pulses together with the analysis of solutions for metal ions shows that the iron dis-solution rate substantially decreases as increases. A bipolar electrode-membrane allowed the determination of the C intervals corresponding to the inhibition of iron dissolution (at C < Cc 
3 
10–8 g-at/cm3), the activating effect of hydrogen absorbed by the metal on the anodic process (for C > Cc), and the metal destruction (for C >> Cc). The absorbed hydrogen is assumed to accelerate the ionization of iron due to the formation of new dissolution sites as a result of plastic deformations of the metal. Thus, the effects of two forms of sorbed hydrogen on the iron dissolution are separated.
solutions (pH 1.30) by cyclic potential pulses. Expressions that allow one to calculate the hydrogen coverage on the iron surface () as a function of the potential variation in a cyclic stepwise manner and also the hydrogen concentration in the near-surface metal layer (C) as a func-tion of variations in the intensity of the diffusion flow of hydrogen atoms in the membrane are given. The method of cyclic potential pulses together with the analysis of solutions for metal ions shows that the iron dis-solution rate substantially decreases as increases. A bipolar electrode-membrane allowed the determination of the C intervals corresponding to the inhibition of iron dissolution (at C < Cc 3 10–8 g-at/cm3), the activating effect of hydrogen absorbed by the metal on the anodic process (for C > Cc), and the metal destruction (for C >> Cc). The absorbed hydrogen is assumed to accelerate the ionization of iron due to the formation of new dissolution sites as a result of plastic deformations of the metal. Thus, the effects of two forms of sorbed hydrogen on the iron dissolution are separated. DOI: 10.1134/S0033173207070016