Corrosion and electrochemical investigations for stainless steels in molten Solar Salt: The influence of chloride impurity

Li, Heng; Wang, Xiaowei; Yin, Xuzhong; Yang, Xinyu; Tang, Jianqun; Gong, Jianming

doi:10.1016/j.est.2021.102675

Cited by 22 publications

(4 citation statements)

References 29 publications

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“…This was related to the standard Gibbs free energy of the main elements of the Hastelloy N involved in producing fluoride corrosion products. Corrosion in molten salt is an impurity-driven process [34][35][36] , and typical impurities include H 2 O and SO 4 2-. The impurities in the salt provide pathways for corrosion by forming relatively unstable fluorides, such as HF, which tend to corrode the alloy materials by a reaction such as…”

Section: Corrosion Product Characterisationmentioning

confidence: 99%

Stress-assisted corrosion behaviour of Hastelloy N in FLiNaK molten salt environment

Zhang

et al. 2022

npj Mater Degrad

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The use of molten-salt–based energy production and storage systems requires high-temperature corrosion- and creep-resistant structural materials. This study investigated the microstructure evolution and corrosion characteristics of Hastelloy N under working stress in a molten salt environment. Selective diffusion of Cr at the grain boundaries (GBs) of the Hastelloy N degraded the properties of the GBs, making them preferred locations for corrosion crack invasion. Stress further promoted Cr diffusion and accelerated GB carbide precipitation, thereby forming a corrosion couple between the carbide and matrix that facilitated the expansion of intergranular corrosion cracks into the grains. These findings are useful for providing advances in the design of novel structural alloys with extraordinary property-microstructure stability combinations for resistant to complex molten salt environments.

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Section: Corrosion Product Characterisationmentioning

confidence: 99%

Stress-assisted corrosion behaviour of Hastelloy N in FLiNaK molten salt environment

Zhang

et al. 2022

npj Mater Degrad

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“…At present, molten nitrate salts and austenitic stainless steels have been applied in CSP systems that operate commercially. Moreover, the research on materials and degradation is of interest to extend the service life of CSP system components [11][12][13][14][15][16]. Wang et al studied the corrosion of AISI 310S, AISI 316L, and AISI 321 in a quaternary molten…”

Section: Introductionmentioning

confidence: 99%

Intergranular Corrosion Analysis of Austenitic Stainless Steels in Molten Nitrate Salt Using Electrochemical Characterization

Kanjanaprayut,

Siripongsakul,

Promdirek

2024

Metals

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This study investigates the influence of molten nitrate salt exposure on the intergranular corrosion (IGC) behavior of three grades of austenitic stainless steel (namely, AISI 304, AISI 304H, and AISI 321H). Two electrochemical techniques, double loop electrochemical potentiokinetic reactivation and potentiodynamic polarization methods, are applied after stainless steel is exposed to 600 °C molten nitrate salt, 60% NaNO3, and 40% KNO3 for varying immersion durations. Corrosion morphology is examined using optical microscopy and scanning electron microscopy images to assess susceptibility to IGC. IGC is prompted by the presence of chromium carbides at grain boundaries, which leads to chromium depletion around these carbides. The findings of the experiments reveal distinct IGC behavior among stainless steel grades. For AISI 304, the degree of sensitization (DOS) increases as exposure time progresses. However, AISI 304H and AISI 321H stainless steel exhibit diminishing DOS after 100 and 10 h of exposure, respectively. This trend is attributed to desensitization or the healing effect when stainless steel is exposed to molten salt for a prolonged time. The depletion and recovery of Cr near grain boundaries are confirmed by the inverse relationship to DOS of pitting potential.

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“…However, the effect of chloride impurity on fluxing of corrosion products is not mentioned. According to Li et al, [ 14 ] sodium ferrite was found at 3000 h in the salts with chloride‐free, while it can be found at 500 h in salts containing chloride. Sodium ferrite is formed according to reaction ():

{\mathrm{Fe}}_{2}{{\rm{O}}}_{3}+{\mathrm{Na}}_{2}{\rm{O}}\leftrightarrow 2{\mathrm{NaFeO}}_{2}.

…”

Section: Introductionmentioning

confidence: 99%

Impact of NaCl impurity on corrosion of 316 L steel in molten nitrate salts for thermal energy storage: An electrochemical study

Wang

Feng

et al. 2022

Materials & Corrosion

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The impact of NaCl impurity on corrosion of stainless steel (SS) 316 L in binary nitrate salts (60 wt% NaNO 3 + 40 wt% KNO 3 ) was systematically investigated at 565°C via electrochemical measurements. SS 316 L exhibits active dissolution behavior in salts containing 0-1.4 wt% NaCl. The influence of NaCl impurity shows a strong time dependence according to the negligibly affected corrosion current density obtained from a short-time potentiodynamic polarization sweep. The corrosion process of 316L in salts with NaCl-free is controlled by ions transport through the oxide layer. With the presence of NaCl impurity, it is controlled by higher rate of ions transport and the diffusion of metal chlorides. The alternation in basicity in the corrosion front caused by chloride ions increases the solubility of chromium oxide and hence the dissolution of chromium oxide, which can lead to the formation of a less protective oxide layer.

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Corrosion and electrochemical investigations for stainless steels in molten Solar Salt: The influence of chloride impurity

Cited by 22 publications

References 29 publications

Stress-assisted corrosion behaviour of Hastelloy N in FLiNaK molten salt environment

Stress-assisted corrosion behaviour of Hastelloy N in FLiNaK molten salt environment

Intergranular Corrosion Analysis of Austenitic Stainless Steels in Molten Nitrate Salt Using Electrochemical Characterization

Impact of NaCl impurity on corrosion of 316 L steel in molten nitrate salts for thermal energy storage: An electrochemical study

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