Influence of peroxocompounds on corrosion of mild steel and admiralty brass in aqueous solution

Peroxocompounds (POC) are very strong oxidizing compounds influencing various physico-chemical processes. The objective of this work is to study corrosion and electrochemical behavior of mild steel (C1010) and Admiralty brass (CDA 443) in different aqueous solutions and in a simulated cooling water solution in the presence of various concentrations of peroxoborates and peroxocarbonates. The weight loss, the potentiodynamic (PD), the linear polarization resistance (LPR) and the potential-time measurements were used. Corrosion tests showed that the corrosion rate increased when POC was added in low concentrations and diminished with further addition of POC. This means that POCs behave as anodic inhibitors. The maximum on the curve "corrosion rate - POC concentration" and protective concentration values of POC (efficiency more than 90%) depend on the type of POC, the nature of the alloy and concentration of electrolyte in water. Addition of POC to water increases pH. Efficiency of POC does not relate to pH. The electrochemical study showed that POC's influence both anodic and cathodic corrosion reactions at the metal surface.