engleski

Corrosion and scale control of carbon steel in the near neutral media by a nontoxic inhibitor

Tannins, ecologically acceptable compounds, have been used for many years to promote the protection of rusted steel, mainly in paints or wash primers, and also for deposit control in the feed water and in cooling water systems. The efficiency of tannins as inhibitors depends of nature of corrosion products on metal surface, the protection of the clean surface being negligible. It has been generally accepted that the tannin reacts with steel to form a cracked layer of ferric tannate in presence of air, which impregnates the rust. As tannin increases the acidity when added in neutral aqueous solution, Fe(III) tannate is dissolved resulting in low inhibiting efficiency. Calcium gluconate was used in blends with different form of tannins, pure tannic acid, mimosa tannin and quebracho extract to study the inhibition effect for carbon steel. It was found that mixtures perform better protection than tannin or calcium gluconate respectively, as revealed by low limiting current on anodic curve recorded by potentiodynamic polarization measurements.

tannin; corrosion of steel; scale control of carbon steel; nontoxic inhibitor

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