Frolenkova S. Combinated oxyanion passivators for mild steels corrosion protection

The dissertation is devoted to studing of processes of mild steel anodic and chemical passivation by oxoanions of elements V -VII groups of periodic table in acidic, neutral and alkaline solutions. The most effective passivators are oxoanions with central atom of halogen (BrO3-, ІO3- ), and the most stable films form in the presence of molibdates. The causes of effective passivating action of bromates are high oxidizing properties and the most high current of halogen cathodic reduction than anodic current of steel dissolution. The inhibition of anodic process by molybdates causes by adsorption of oxyanion on the steel surface and its inclusion in oxide passive film. It was developed methods for estimating stability and protection properties of passive films, which base in comparative analysis of electrochemical characteristics of passivated steel and steel without passivating treatment. It was developed the passivating inhibitors - oxoanions mixes, which protect the mild steels in low mineralized water, acetic antifreezing and acidic nitrate solutions. The protection degree by passivating inhibitors comes to 94 - 96%. Based on electrochemical and corrosion investigations, it were founded the compositions for getting the conversion coatings on the mild steel surface for protection from atmospheric corrosion. The protection degree by oxide modified conversion coverage comes to 98 - 99%.