Corrosion inhibition of D16T aluminum alloy by sodium alginate and zinc acetate composition in neutral chloride-containing environment

The effect of an environmentally safe inhibitory composition based on polysaccharide (sodium alginate) and acetic acid salt (zinc acetate) on the corrosion of aluminum alloy in a neutral chloride-containing environment was studied. The anticorrosion efficiency of the composition and the peculiarities of the mechanism of its protective action were established based on electrochemical studies. The degree of metal protection by the alginate-acetate composition, calculated according to polarization dependences, was 89–98%. The anti-corrosion effect of the composition is explained by the formation of a protective film on the surface of the alloy due to the adsorption of alginate, the deposition of zinc hydroxides on the cathode areas of the metal and, probably, the formation of poorly soluble Al³⁺–Zn²⁺-alginate complexes. The formation of the protective film on the surface of the alloy in inhibited solutions was confirmed by the results of electrochemical impedance spectroscopy, scanning electron microscopy, and Energy-dispersive X‑ray analysis.