Semiconductivity Conversion of Passive Films on Alloy 800 in Chloride Solutions Containing Various Concentrations of Thiosulfate

Xia, Da-Hai; Fan, Hongzhen; Yang, Lixia; Behnamian, Yashar; Luo, Jing‐Li; Lu, Yucheng; Klimas, Stan J.

doi:10.1149/2.0611509jes

Cited by 23 publications

(27 citation statements)

References 17 publications

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“…As a result, the passive film cannot be broken down in this situation. In our previous work, 39 we found that there is not pits formed on UNS N08800 surface after the polarization curve conducted in solution containing 0.1 mol · L −1 + 0.5 mol · L −1 S 2 O 3 2− . 39 The experimental observation verified that there is no pitting corrosion occurred if the chloride/thiosulfate concentration ratio is very low.…”

Section: Chloride-to-thiosulfate Concentration Ratio (Ctcr)-ctcr Ismentioning

confidence: 76%

Factors Influencing Passivity Breakdown on UNS N08800 in Neutral Chloride and Thiosulfate Solutions

Wang

Shi

et al. 2017

J. Electrochem. Soc.

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In this work, the passivity degradation of UNS N08800 in solutions containing Cl − and S 2 O 3 2− is studied by using polarization curve, electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). Experimental results reveal that the passivity breakdown heavily depends on anodic potentials, concentration ratios of Cl − to S 2 O 3 2− , and the composition of materials. A combined effect between Cl − and S 2 O 3 2− on pitting corrosion is observed at high anodic potentials at which the passive film is broken down; in this situation, S 2 O 3 2− ions can enter into the pits by electromigration, and they are reduced to S ads and S 2− , stabilizing the metastable pits and accelerate the pit growth rate. However, there is no such combined effect at low anodic potentials when the passive film is intact, on the contrary, S 2 O 3 2− is beneficial to passivity in chloride solutions. At low anodic potentials, the interaction of S 2 O 3 2− with an intact passive layer is weak, and the adsorption of S 2 O 3 2− would mitigate the detrimental effect of Cl − ions.

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Section: Chloride-to-thiosulfate Concentration Ratio (Ctcr)-ctcr Ismentioning

confidence: 76%

Factors Influencing Passivity Breakdown on UNS N08800 in Neutral Chloride and Thiosulfate Solutions

Wang

Shi

et al. 2017

J. Electrochem. Soc.

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“…Therefore, no pits are initiated at a lower chloride-tothiosulfate concentration ratio [12,21]. The concentration of these two ions could affect the semiconductivity of passive film formed on alloy 800, and the semiconductivity type changes from n-type to p-type as the concentration ratio decreased, which was due to sulfur incorporation into oxygen vacancies [21].…”

Section: Methodsmentioning

confidence: 99%

“…For example, Cui et al [9] used scanning reference electrode to measure the surface potential distribution. Zhu et al [10,11] and Xia et al [12,13] used scanning electrochemical microscope (SECM) to obtain the surface reactivity of alloy 800 in chloride and thiosulfate solutions. Zhao et al [14] used Scanning Kelvin Probe (SKP) to study the potential distribution of a crack on 304 stainless steel.…”

Section: Introductionmentioning

confidence: 99%

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

Xia

Luo

Gao

et al. 2015

Acta Metall. Sin. (Engl. Lett.)

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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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“…S 2 O 3 2¹ can also affect the materials used in the nuclear industry. [20][21][22][23][24][25][26] Wang et al 27 found that the passive range and pitting corrosion potential of Alloy 800 in the solution containing both thiosulfate and chloride ions are lower than that in thiosulfate-only or chloride-only solutions or the sulfate + chloride ions. Z. Fang and R. W. Staehle investigated surfaces of Alloys 600, 690 and 800 after polarization over the potential range and found intergranular (IG) corrosion occurred mainly in a solution of SO 4 2¹ , sulfite (SO 3 2¹ ), tetrathionate (S 4 O 6 2¹ ), and S 2 O 3 2¹ , while S 2¹ or HS ¹ were found to produce pitting.…”

Section: ¹mentioning

confidence: 99%

Pitting Corrosion Mechanism of Alloy 800 in Simulated Crevice Chemistries Containing Thiosulfate

Gao

Xia

et al. 2016

Electrochemistry

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Interaction of thiosulfate with Alloy 800 was systematically investigated to obtain the kinetics in a neutral simulated steam generator crevice solution. Cyclic polarization showed that the pitting potential in a thiosulfate-chloride solution was much lower than in either a chloride solution or a sulphate-chloride solution, and thiosulfate selectively and distinguishably degraded the oxide film on Alloy 800. The donor density of oxide film formed in a thiosulfatechloride solution was slightly higher than in either a chloride-only solution or a sulphate-chloride solution. Even in the passivity range the material was degraded due to the slow interaction with S 2 O 3 2− with oxide, especially when the applied potential was close to the pitting potential. The UV-visible absorption spectra showed that thiosulfate formed a stable complex with Cu 2+ , and their product was soluble in aqueous solution, which is possible evidence to indicate that thiosulfate assists Cu 2+ in dissolving from an oxide film into solution. Also, due to the complexity of the reaction, thiosulfate decreased the oxidation potential of Cu 0 to Cu 2+ . Since the Cu, an impurity in Alloy 800, normally accumulates at the grain boundary, especially at the triple points, thiosulfate induced corrosion is in the form of pitting or intergranular attack.

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Semiconductivity Conversion of Passive Films on Alloy 800 in Chloride Solutions Containing Various Concentrations of Thiosulfate

Cited by 23 publications

References 17 publications

Factors Influencing Passivity Breakdown on UNS N08800 in Neutral Chloride and Thiosulfate Solutions

Factors Influencing Passivity Breakdown on UNS N08800 in Neutral Chloride and Thiosulfate Solutions

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

Pitting Corrosion Mechanism of Alloy 800 in Simulated Crevice Chemistries Containing Thiosulfate

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