Development and Optimization of Synergistic Compositions for the Corrosion Protection of Steel in Neutral and Acid Media
- PDF / 1,651,764 Bytes
- 9 Pages / 594 x 792 pts Page_size
- 102 Downloads / 168 Views
DEVELOPMENT AND OPTIMIZATION OF SYNERGISTIC COMPOSITIONS FOR THE CORROSION PROTECTION OF STEEL IN NEUTRAL AND ACID MEDIA V. М. Ledovs’kykh,1 Yu. P. Vyshnevs’ka,1, 2, 3 І. V. Brazhnyk,4 and S. V. Levchenko1
UDC 620.197
We study the conditions of appearance of synergistic effects in inhibiting mixtures aimed at the protection of steel against corrosion in neutral aqueous-salt and acid media. It is shown that the high anticorrosion efficiency in neutral media is attained by the application of inhibitors with different mechanisms of action guaranteeing the efficient passivation in a broad range of potentials. We propose an approach to the optimization of complexing synergistic compositions for the protection of steel in acid media, which enables one to increase their efficiency as a result of the improvement of the microstructure of the phase layer. It is shown that the method of isomolar series opens wide possibilities for the investigation of the nature and conditions of the formation of synergistic effects. Keywords: corrosion, inhibitor, protection of the metal, isomolar series, complex compounds, phase layers.
As a promising direction in the development of the methods of corrosion protection in different media, we can mention the creation of highly efficient inhibiting mixtures characterized by superadditivity of the action of their components. In acid solutions, the process of corrosion of steel runs as a result of the conjugate cathodic reaction of reduction of H + ions and the phenomenon of synergism is observed either in combinations of cationic and anionic surface-active substances (SAP) (this is the so-called intermolecular synergism) or in the case of application of SAP whose molecules contain both cationic and anionic functional groups (intramolecular synergism). According to the concept of the adsorption mechanism of their action, one can explain the observed synergistic effects by high degrees of filling of the metal surface (close to the ultimate values). This is possible due to the mutual attraction of oppositely charged groups in their adsorption layer, which leads to the strong inhibition of anodic, cathodic, or both electrode reactions [1–9]. In neutral aqueous-salt solutions, the conjugate cathodic reaction of corrosion is the reduction of O 2 molecules dissolved in aqueous media characterized by the diffusion mechanism. As a result of the direct and lateral delivery of depolarizer to the metal surface, the satisfactory degree of deceleration of corrosion is possible only under the conditions of dense blocking of the surface. Therefore, it is customary to protect steel by means of retardation of the anodic reaction of ionization of the metal as a result of transition of its surface into the passive state. The synergistic effects were revealed in the course of application of the mixtures of inhibitors, namely, inorganic passivators with adsorption organic SAP. Thus, the mixtures of organic amines with sodium nitrite 1 2 3 4
National Aviation University, Kyiv, Ukraine.
“Kyiv Polytechnic Institute”
Data Loading...
