INFLUENCE OF HYDROGEN SULFIDE ON THE CORROSION-ELECTROCHEMICAL PROPERTIES OF 20 STEEL WITH COATINGS BASED ON ZINC AND ALUMINUM

We study the corrosion of a hot-dip zinc coating and arc-sprayed aluminum and zinc coatings in chloride- acetate solutions and model seawater saturated with hydrogen sulfide. It is shown that, in chloride-acetate solutions, hydrogen sulfide promotes an increase in the corrosion rate of 20 steel by more than an order of magnitude. For the hot-dip zinc coatings, hydrogen sulfide does not change the corrosion rate, whereas for the arc-sprayed coatings, it decreases the corrosion rate by a factor of similar to 5. The saturation of model seawater with hydrogen sulfide decreases the corrosion rate of 20 steel by a factor of similar to 7 and the corrosion rate of the hot-dip zinc coating by a factor of similar to 1.4 but does not affect the corrosion rate of the arc-sprayed coating. The insoluble corrosion product of zinc, namely, its sulfide, does not passivate these coatings. Hydrogen sulfide leads to an insignificant increase in the corrosion rate of the arc-sprayed aluminum coating both in a chloride-acetate solution and in model seawater. Its values are 3-7 times lower than for 20 steel, which indicates the possibility of application of the coatings based on aluminum for the corrosion protection of steels in hydrogen-sulfide-containing media.