Korniy S. Prediction of interaction mechanisms of metallic systems with corrosive environment by quantum chemistry methods

The dissertation provides novel insights into the theoretical evaluation and prediction of corrosion resistance of multicomponent metallic systems along with the establishment of their local corrosion damage mechanisms based on the development of atomic-molecular models of processes in the metal-environment space. This work also contributes to the improvement of quantum-chemical calculations for the multicomponent systems using the density functional method in a cluster approximation. Based on the quantum-chemical density functional method, we have calculated the interaction of components of a corrosive environment with a surface and also the activation barriers of metal atoms ionization taking into account the influence of the aqueous medium and the charge state of corrosion ions and the surface. This approach has allowed us to evaluate the ways of metal corrosion in alkaline and acidic environments using an aluminum alloy intermetallide as an example substance. In addition, we could predict the corrosion-morphological stability of binary platinum nanoparticles with the shell structure of PtMe (Me – Cr, Fe, Co, Ni, Ru) in the low-temperature fuel cell environment. Next, using data-calculation analysis, we have determined the interaction between the intermetallic phases of aluminum alloys Al2Cu and Al2CuMg and corrosive environment, which allowed to propose an alternative mechanism for alloy corrosion and to explain the existing experimental results. Moreover, we have theoretically substantiated the inhibitory effect of modified zeolites and surface-active ramnolipid biocomplexes on aluminum alloys. In addition, we have revealed the possibility of formation of stable rhamnolipid complexes with aluminum ions that can precipitate on the metal surface forming an organic barrier layer, thereby preventing metal corrosion. We have also predicted the mechanism of synergistic interaction of rhamnolipids with calcium and zinc phosphates, which contributes to lipid solubilization. The established relationships between chemical composition, crystall structure, the nature of chemical bonding in binary platinum nanoclusters and their reactivity enable us to provide practical recommendations for the prediction of properties and creation of new efficient binary platinum-based nanomaterials for low-temperature fuel cells.