Page 10 - Дисертація_Сободош_Наталія_Йосипівна

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significantly reduces the alloy's corrosion rate. A prolonged protective effect of the

composition was observed: the impedance modulus remained two orders of

magnitude higher than in the uninhibited medium for 168 hours of exposure.

The inhibitory effect of this composition is explained by the ability of alginate

molecules, due to their hydroxyl and carboxyl functional groups, to adsorb onto the

2+
surface of the aluminum alloy and to form poorly soluble complexes with Zn
cations released during the dissolution of zinc acetate. As a result, the adsorbed

alginate film may further compact. At the same time, a protective layer of zinc

hydroxide molecules may form on the cathodic regions of the aluminum alloy, which

reduces the rate of the oxygen reduction reaction. The results of the analysis of IR

spectra of the inhibited alloy surface indicate the formation of aluminum-alginate

complexes on the alloy surface and the formation of a coordination bond between

acetate ions and aluminum cations.

The results of the study of the structure, morphology, and chemical

composition of protective films formed on the surface of the aluminum alloy in an

inhibited environment are presented. Using a set of physicochemical methods, the
formation of an organo-inorganic protective layer based on aluminum and zinc

alginate complexes was established.
A synergistic mechanism for the protective action of the developed inhibitory

composition is proposed, realized through the formation of a stable organo-inorganic
film with the localization of the inhibitory action of the components on the

heterogeneous surface of the alloy: alginate complexes with aluminum and zinc are

deposited predominantly on anodic areas, whereas on cathodic areas a film of

sparingly soluble zinc oxides or hydroxides forms, which neutralizes the effect of

the alloy’s intermetallics by reducing the rate of the cathodic reaction and ensures

mixed corrosion control.

Chapter 4 presents the results of comprehensive studies on the protective

efficacy of the developed inhibitory composition during the repassivation stage of a

mechanically activated surface of D16T aluminum alloy. Particular attention is paid

to the kinetics of the metal’s return to a passive state under conditions of periodic