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These results make methodological adjustments for experiments conducting with
varying rates of scan potential. Thus, for metals hydrogenation, the dependencies are
obtained starting from the potential of zero current without cathode polarization.
In the solution of sodium sulphide the process of Armco iron passivation is
characterized by lower currents than in sodium hydroxide solution. According to the
anodic polarization deepening the anode current increases due to the sulphides
transformation and degradation of their protective properties, indicating the formation
of hydrogen sulphide in sulphide containing environments with different
electrochemical properties. They can have a different impact on the hydrogen release
process, which is very sensitive to the state of the surface which it flows.
The hydrogen sulphide influence on cathode and anode processes, which occur
in chloride and acetate-containing environments on Armco iron is estimated. It was
shown, that this influence has a stronger impact on the rate of cathode reactions,
which increase in 2.7 ... 6.0 times. The formation of pyrite, troilite and kansite on
Armco iron increases the volume of allocated hydrogen due to cathode polarization.
Sulphides, with the exception of pyrite, reduce cathode overvoltage. All of them
contribute to increasing of allocated hydrogen volume, but this is not accompanied by
symbiotic increasing process. On the basis of results analysis, it was concluded that
sulphides preferentially slow down the catalytic reaction of hydrogen atoms
recombination.
An addition, to the generalized scheme based on literature data, the mechanism
of hydrogen sulphide influence on corrosion rate and hydrogenation of steels is
proposed. This generalized scheme does not take into account the sparingly soluble
sulphides as corrosion formation on steels surface. Their composition is determined
mainly by the concentration of hydrogen sulphide in the media. On the basis of the
results obtained in the work, this scheme is expanded by taken into account the
reactions on the steels surface of iron sulphides (pyrite, troilite and kansite)
formation. These iron sulphides influence on the hydrogen over-voltage and the rate
of hydrogen atoms recombination reactions, which is a prerequisite for the absorption
of hydrogen by metals.