Research on surface energy and corrosion resistance by electrochemical processing of 304-Cu stainless steel

In this paper, activation (H7 series), over-passivation (H6 series), and passivation states were presented in the electrochemical processes. 304-Cu stainless steel was treated with two electrolytes (H6, H7), and then passivated by air oxidation, citric acid pickling, or ultraviolet irradiation. The variations of voltage and surface energy described the different stages of the process, corresponding to the changes in morphology, and the evolution of the passivation film. The H6 series with flat surfaces had higher corrosion potential and pitting corrosion potential, and the corrosion current was lower. The H7 series with rough surfaces had a thicker passivation film, poorer pitting corrosion resistance, and the best general corrosion resistance. The formula derived from the Arrhenius equation illustrates the functional relationship between the surface energy and the resistance of the passivation film, and the results validated the conclusions. [Display omitted]