I. M. Zin

SPECIFIC FEATURES OF THE ANTICORROSIVE ACTION OF A MIXTURE OF NONTOXIC PIGMENTS IN AN EPOXY COATING ON STEEL

We investigate capacitance-resistance characteristics of epoxy coatings on low-carbon steel that contain a strontium crown or a mixture of phosphate and calcium-containing pigments in a primer. Tests were carried out in a medium simulating acid atmospheric precipitation. The protective action of chromate-free pigments hinders the diffusion of an acid medium into a polymeric coating and improves its insulating properties. The swelling of free films and the capacitance of coatings with chromate-free pigments are lower than those of epoxy and epoxychromate coatings. We establish the existence of an incubation period in the protective action of pigmented coatings. In both pigmented coatings, an increase in both the active resistance and frequency dependence is observed. The results of impedance tests show that the anticorrosive efficiency of epoxy coatings with a mixture of nontoxic pigments is on a par with the anticorrosive efficiency of epoxychromate coatings.

Improvement of the Anticorrosion Properties of a Working Emulsion of Mine Hydraulic Systems

We seek new efficient corrosion inhibitors for the protection of steel rods of mine hydraulic cylinders with electric-arc sprayed coatings against corrosion in the FMI-RZh working emulsion contaminated with chloride ions. A significant deceleration of the corrosion fracture of 45 steel is detected after the addition of sodium silicate and benzyl benzoate to the emulsion. The inhibiting effect of benzyl benzoate can be explained by the adsorption of its polar molecules on the steel surface and by the formation of sodium benzoate as a result of the reaction with hydroxyl ions near the cathodic sections. Both inhibitors provide the efficient corrosion protection of the “45 carbon steel–electric-arc sprayed powder-wire coating” system in a 3% solution of sodium chloride under the conditions of leakage of the inhibited emulsion through the porous sprayed layer.

Influence of a Rhamnolipid Biocomplex on the Corrosion of Duralumin in the Case of Mechanical Activation of its Surface

The problem of inhibition of the corrosion of D16T aluminum alloy by surface-active products obtained as a result of the biosynthesis of Pseudomonas sp. PS-17 strain (rhamnolipid biocomplex) is studied by using the electrochemical and quantum-chemical methods. It is shown that the rhamnolipid biocomplex is capable of the efficient inhibition of the corrosion of D16T aluminum alloy in a synthetic acid rain. The efficiency of inhibition increases with the concentration of biosurfactant. As the critical concentration of micelle formation is attained, a subsequent increase in the amount of biosurfactant in corrosive media does not lead to any noticeable intensification of its protective (anticorrosion) effect. The mechanism of corrosion inhibition is connected with the adsorption of biosurfactant molecules on the surface of aluminum alloy with the creation of barrier films and the formation of difficultly soluble complex compounds on the anodic sections of the metal as a result of the interaction of rhamnolipid with aluminum ions. The rhamnolipid biocomplex efficiently prevents the corrosion of aluminum alloy in the case of its mechanical activation. The biosurfactants added to the corrosive medium increase the rate of recovery of protective films on the aluminum alloy in the stage of repassivation by a factor of 2–4, as compared with the uninhibited medium.