Corrosion inhibition mechanism of Na2CrO4 on 316L in highly concentrated NaOH solutions

• Published in: Journal of Materials Research and Technology
• Main Authors: Chunliu Li, Zhu Wang, Biao Liu, Shaona Wang, Hongwei Xie, Lei Zhang, Hao Du, Yi Zhang
• Format: Article
• Language: English
• Published: Elsevier 2025-03-01
• Subjects: Corrosion inhibitor; Concentrated NaOH solutions; High-temperature; Passive film; TEM
• Online Access: http://www.sciencedirect.com/science/article/pii/S2238785425003837

The corrosion inhibition behavior of Na2CrO4 on 316L in high-temperature concentrated NaOH solution was investigated. The results indicated that Na2CrO4 effectively inhibited the corrosion of 316L. The addition of Na2CrO4 induced the variation of film composition from Ni-rich to Cr-rich. TEM results showed that in the absence of Na2CrO4, the inner and outer films exhibited lattice fringe structures. In the presence of Na2CrO4, the inner and outer layers of the passive films exhibited amorphous structures. CrO42− exhibited a mixed mode of adsorption involving chemisorption and physisorption. Chemisorption promoted the formation of Cr-rich protective passive films. Physisorption was beneficial for the self-healing of localized defects in passive films. Besides, the presence of Na2CrO4 induced the competitive adsorption of CrO42− with OH−, which reduced the corrosion susceptibility of 316L.