Role of Ni in improving corrosion resistance by comparing the corrosion behavior of 316L and SUS430 in concentrated NaOH solution

Purpose This paper aims to study the role of Ni in improving corrosion resistance by comparing the corrosion behavior of 316L and SUS430 in 50 Wt.% NaOH solution. Design/methodology/approach The passive film properties and corrosion behavior were comparatively investigated by electrochemical tests in 50 Wt.% concentrated NaOH solution. The chemical compositions of the passive films were analyzed by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry. Findings The results showed that forming Cr- and Ni-enriched outer passive films on 316L (Ni-containing) inhibited OH – penetration and significantly suppressed the corrosion process. On the contrary, a large amount of Fe dissolution occurred in the passive film of SUS430 (without Ni), which destroys the structure of the passive film. In addition, Ni in 316L promoted the formation of Ni-Fe spinel oxides in the outer passive film, further reducing the selective dissolution of Fe and making the passive film more stable. Originality/value The role of Ni in improving corrosion resistance was investigated by comparing the corrosion behavior of 316L and SUS430 in 50 Wt.% NaOH solution. It revealed the corrosion behavior of materials in concentrated alkali solution and provided relevant data support for protection in concentrated alkali environments.