Effect of chloride ion on the corrosion behavior of SiN stainless steel in concentrated hot nitric acid media.

The effect of Cl− on the corrosion behavior of SiN stainless steel (SS) in simulating spent fuel reprocessing environment was systematically investigated. The results indicated that both cathodic and anodic behaviors of SiN SS were altered and multiple current peaks were observed as Cl− concentration increased. Meanwhile, there existed a critical Cl− concentration beyond which SiN SS transitioned from passive state to active dissolution state. Furthermore, a formulation for multiple current peaks was put forward based on mixed potential theory, and the corrosion mechanism in hot nitric acid with various Cl− concentrations was proposed involving the competitive adsorption of ions. • Cl− cannot induce pitting corrosion of SiN steel in 6 M hot nitric acid media. • Both cathodic and anodic behaviors of SiN steel in nitric acid are altered by Cl−. • Multiple current peaks are observed in nitric acid with 0.4 M Cl− and 0.45 M Cl−. • A critical concentration of Cl− with remarkable dissolution rate is determined. • Mechanism of Cl− on the corrosion of SiN steel in nitric acid is proposed. [ABSTRACT FROM AUTHOR]