Monitoring the Diffusion Layer During Passive Film Breakdown on Alloy 800 with Digital Holography

Da-Hai Xia^1,2,3，Jing-Li Luo³，Zhi-Ming Gao^1,2，Bo-Yu Yuan⁴，Liang Li⁵，Chao Wang⁵

1. Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University2. School of Materials Science and Engineering, Tianjin University3. Department of Chemical and Materials Engineering,University of Alberta4. School of Physics and Electronic Engineering, Jiangsu Normal University5. School of Chemistry and Chemical Engineering, Jiangsu Normal University

摘 要：The effects of chloride and thiosulfate ions on localized corrosion of alloy 800 are investigated through dynamical observation of the change in phase image of the diffusion layer during passive film breakdown using digital holography. The results indicate that solution chemistry has a significant effect on film breakdown and diffusion layer. The phase distribution changes at different applied potentials show that in the process of film breakdown, dissolution of metal ions from pitting is not remarkable in chloride-only solution, whereas dissolution of metal ions is significantly high in thiosulfate and chloride solution. Thiosulfate has a combined effect with chloride ions in passive film degradation.

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