Galvanic corrosion of pure metals in molten fluorides

Wang, Yanli; Liu, Huijun; Zeng, Chaoliu

doi:10.1016/j.jfluchem.2014.05.010

Cited by 49 publications

(30 citation statements)

References 14 publications

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“…[15]. A ternary eutectic mixture of 46.5LiF-11.5NaF-42KF (mole percent) was used for the corrosion study.…”

Section: Methodsmentioning

confidence: 99%

“…However, I corr in Ar-5%H 2 O is 374 mA cm À2 more than three times the value of 108 mA cm À2 in Ar, indicating that the corrosion of the alloy is accelerated significantly by 5%H 2 O. In a study of the electrochemical behavior of pure Ni, Fe and Cr in molten (Li,Na,K)F at 700 8C under Ar [15], the present authors reported that I corr of Ni and Cr is 19.3 and 494 mA cm À2 , respectively. I corr for GH3535 is significantly lower than that for pure Cr, but still obviously larger than that for pure Ni.…”

Section: Introductionmentioning

confidence: 98%

“…These electrochemical techniques have been proved effective in understanding the corrosion mechanism and kinetics, with more information obtained for the corrosion processes. There have been some reports on the electrochemical investigation of corrosion in molten fluorides [10][11][12][13][14][15], but with the emphasis on the determination of oxidation states, suitable electrode materials and basic electrochemical characteristics of specific elements using cyclic voltammetry [13]. Recently, the present authors [14,15] investigated the corrosion behavior of pure Ni, Fe and Cr in molten (Li,Na,K)F by some electrochemical methods and observed dramatic galvanic corrosion, with the most significant galvanic corrosion effect for the couple Ni/Cr [15].…”

Section: Introductionmentioning

confidence: 99%

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Electrochemical study of the corrosion of a Ni-based alloy GH3535 in molten (Li,Na,K)F at 700°C

Wang

Liu

et al. 2015

Journal of Fluorine Chemistry

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“…[15]. A ternary eutectic mixture of 46.5LiF-11.5NaF-42KF (mole percent) was used for the corrosion study.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Electrochemical study of the corrosion of a Ni-based alloy GH3535 in molten (Li,Na,K)F at 700°C

Wang

Liu

et al. 2015

Journal of Fluorine Chemistry

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“…Reactions 3 and 6 can be rewritten as a simplified format of Equations 7 and 8: 9 Reduction reaction : 2Cr 3+ + 2e − → 2Cr 2+ [7] Oxidation reaction : Mg → Mg 2+ + 2e…”

Section: Model Developmentmentioning

confidence: 99%

“…4,8,9 Adding a sacrificial anodic species, such as Mg, to the system can hold the redox potential of the salt at a point where Cr dissolution from superalloys into the molten salt is suppressed. 8 Additionally, Mg metal has a significant solubility in KCl-MgCl 2 , 10,11 potentially allowing for a buffering effect on the salt redox chemistry.…”

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confidence: 99%

Modeling the Effect of Cathodic Protection on Superalloys Inside High Temperature Molten Salt Systems

Mehrabadi

Weidner

García-Díaz

et al. 2017

J. Electrochem. Soc.

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Cathodic protection is one way to mitigate corrosion of metal surfaces of concentrated solar power (CSP) systems, by shifting the potential of the alloy below its open circuit potential (OCP). The behavior of molten salt CSP systems under cathodic protection can be obtained by developing a three-dimensional (3-D) computational corrosion model. A corrosion model was designed for and benchmarked against a thermosiphon reactor. For the cathodic protection case, magnesium (Mg) was added to the salt as a sacrificial anodic species, which reduces the corrosion rate by cathodic polarization of a corroding metal surface. The model then calculated the new corrosion rate at the surface of the coupons. Results were in good agreement with experimental values for the cases with and without the cathodic protection and at isothermal and non-isothermal conditions. The results showed that by adding even small amounts of Mg into the molten salt (KCl-MgCl 2 ) can rapidly reduce the corrosion rate at the surface of the coupons for both isothermal and non-isothermal conditions. The predicted results also showed that the corrosion rate of Haynes-230 in KCl-MgCl 2 containing 1.15 mol% Mg was 35 times lower than baseline tests with no cathodic protection and met the DOE SunShot targets. Concentrating solar power (CSP) plants rely on thermal energy from the sun to generate electricity. Because they do not rely on any fossil fuel backup, CSP plants can be considered a clean energy source of the future and have the potential to replace greenhouse gas emitting fossil fuel power plants. 1 To make this system feasible, heat transfer fluids (HTFs) are required that can operate at high temperatures (above 800• C) for long periods of time without significant degradation reaction of either the HTF or the materials of construction for the system. Among different heat transfer fluids, molten halide salts are promising due to their high thermal conductivity, large specific heat, low melting point, low viscosity, and low vapor pressure.2,3 However, material corrosion has been recognized as an issue for metals in contact with molten salts, particularly at high temperatures (700-1000• C). 4 Although Superalloys have been developed for high-temperature applications, they are not able to meet both the high-temperature strength and the high temperature corrosion resistance simultaneously in some of the most promising molten salts. To increase the lifetime operation of the CSP system, it is important to prevent the corrosion of the superalloys. One of the most commonly used methods of retarding corrosion and extending the life of structures is cathodic protection, and this method was investigated herein. Cathodic protection is a well-known method for preventing alloy corrosion in aqueous solutions by shifting the cathodic alloy potential to the previous alloy corrosion potential, either by using impressed current or by using a sacrificial anode.5 However, cathodic protection has little documented experience in high-temperature molten salt systems outside ...

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Corrosion in Molten Salts

2018

High Temperature Corrosion

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Galvanic corrosion of pure metals in molten fluorides

Cited by 49 publications

References 14 publications

Electrochemical study of the corrosion of a Ni-based alloy GH3535 in molten (Li,Na,K)F at 700°C

Electrochemical study of the corrosion of a Ni-based alloy GH3535 in molten (Li,Na,K)F at 700°C

Modeling the Effect of Cathodic Protection on Superalloys Inside High Temperature Molten Salt Systems

Corrosion in Molten Salts

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