INFLUENCE OF TiOSO4 ON THE KINETICS OF FORMATION AND PROTECTIVE PROPERTIES OF OXIDE COATINGS ON AISI 304 STEEL

The influence of titanium thiosulfate, introduced into an aqueous electrolyte, on the features of electrochemical formation of oxide coatings on AISI 304 stainless steel has been studied, with a focus on changes in anodic process kinetics, electrochemical passivation parameters, and the protective properties of the resulting layer. The changes in the transition potential to the passive state, the width of the passive region, and the passivation current density depending on the titanium concentration in the electrolyte were analyzed. It was shown that increasing the content of titanium thiosulfate in the solution promotes a decrease in the passivation onset potential and the formation of a denser protective layer, as evidenced by an increase in polarization resistance and a decrease in anodic current density. Emphasis was placed on the optimal concentration range of TiOSO4 (20 g/L), which ensures maximum efficiency in the formation of the passive layer. Results of potentiodynamic polarization studies in a 3% sodium chloride solution were analyzed, indicating a significant influence of the titanium-containing component on the electrochemical behavior of the steel. It was shown that samples with oxide coatings formed in modified electrolytes are characterized by a shift of the corrosion potential toward more electropositive values by 500–800 mV compared to untreated steel. It was confirmed that the obtained coatings effectively reduce the electrochemical activity of the metal in a chloride environment, as evidenced by a significant reduction in corrosion current density and an increase in polarization resistance. The results of the study highlight the potential of controlled electrolyte modification for the electrochemical formation of stable oxide layers with enhanced corrosion resistance, which is important for the protection of steel structures, particularly under high-temperature conditions and exposure to aggressive environments. This research lays the foundation for further improvement of electrolyte compositions and anodizing regimes for steels, aimed at creating stable protective films for operation in aggressive environments without the need for complex surface post-treatment.