Electrochemical study on hydrogen peroxide passivation during boiler pickling

The linear polarization resistance and AC impedance techniques were applied to test the electrochemical performance of boiler water-cooling pipe steel in hydrogen peroxide solution.The microstructures of the pipe steel passivated in different conditions were observed by SEM.The experiment results show that when the mass fraction of hydrogen peroxide is 0.1%,the pH of the solution is 9.5,the mass concentration of ferrous ions is 100 mg·L^-1 and the mass concentration of chlorine ions is less than 50 mg·L^-1,the better passivation with H₂O₂ can be achieved after pickling with citric acid. An intact passive film has formed on the pipe steel and the corrosion resistance of the pipe steel is optimal.