Corrosion of alumina‐forming austenitic steel in molten nitrate salts by gravimetric analysis and impedance spectroscopy

Fernández, Ángel G.; Rey, Antonio; Lasanta, María Isabel; Mato, S.; Brady, Michael P.; Pérez, F.J.

doi:10.1002/maco.201307422

Cited by 71 publications

(43 citation statements)

References 18 publications

(24 reference statements)

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“…It was shown that the corrosion products include iron‐chromium spinel (FeCr 2 O 4 ) formed via reaction (Eq. ) at the inner side and sodium ferrite (NaFeO 2 ) at the outer side of the oxide scale . The latter does not behave protective and can form as a result of reaction between the hematite and Na 2 O traces existing in molten salt (Eq.…”

Section: Discussionmentioning

confidence: 99%

High temperature corrosion in molten solar salt: The role of chloride impurities

Dorcheh

Durham

Galetz

2017

Materials & Corrosion

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The role of chloride impurities in molten NaNO3‐KNO3 (solar salt) mixture on corrosion behavior of low‐chromium ferritic‐martensitic X20CrMoV11‐1 steel (X20) and stainless steel 316 (SS316) was studied at 600 °C. Gravimetric and metallographic methods were employed to characterize the kinetics of oxidation and the resulting corrosion products. Steel X20 showed non‐protective character in both low‐ (up to 0.02 wt% Cl−) and high‐ (up to 0.25 wt% Cl−) chloride salts by forming a thick and non‐compact oxide scale. A significant increase in weight gain was observed when X20 steel was immersed in the high‐chloride‐containing salt. Furthermore, the scale underwent severe deformation. SS316 showed superior corrosion resistance in both low‐ and high‐chloride salts. Oxide scales formed on both steels included two zones: an outer Na‐rich oxide and an inner mixed oxide based on Fe2O3 and Fe3O4 structures. The morphology and composition of these zones were significantly different on X20 and SS316 steels. A passive Cr‐rich oxide layer at the metal/oxide interface was characterized as a protective layer. In the case of stainless steel 316 this layer showed even higher continuity when tested in the high‐chloride salt resulting in better protection during the isothermal test.

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Section: Discussionmentioning

confidence: 99%

High temperature corrosion in molten solar salt: The role of chloride impurities

Dorcheh

Durham

Galetz

2017

Materials & Corrosion

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“…Goods and Bradshaw [15] have reported a corrosion rate value of [6][7][8][9][10][11][12][13][14][15] lm per year at 570°C for two different stainless steels (SS-304 and SS-316) and 5 lm per year at 316°C for a carbon steel (A36), in contact with 'Solar Salt'. Using gravimetric immersion method, corrosion issues caused by Solar Salt at 390 and 550°C have been studied by Fernandez et al [16], on two different stainless steels (types AISI 304 and 430) and low-Cr ($2%) alloy steel (T22). It has been found that the alloy T22 underwent greatest mass gain as expected for a low Cr content steel, whereas alloys 304 and 430 showed almost zero gain/loss of mass with immersion time up to 2000 h.…”

Section: Introductionmentioning

confidence: 99%

Vapor pressure and corrosivity of ternary metal-chloride molten-salt based heat transfer fluids for use in concentrating solar power systems

et al. 2015

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h i g h l i g h t sApplicability of NaCl-KCl-ZnCl 2 salts for CSP applications is evaluated. Corrosion rates are estimated by electrochemical and immersion methods. Hastelloys show corrosion rates of <10 lm/year at 800°C under anaerobic conditions. g r a p h i c a l a b s t r a c t a b s t r a c t Higher operating temperatures increase efficiency of the concentrating solar power plants but promote faster corrosion of the pipes and vessels made of Hastelloy or stainless steel materials for the moltensalt mixtures. Hastelloys C-276 and C-22 and stainless steel 304 coupons evaluated in the present study in a eutectic molten salt consisting of 13.4 mol% NaCl, 33.7 mol% KCl and 52.9 mol% ZnCl 2 showed substantially lower corrosion rates in the absence versus presence of air from 200 to 800°C as determined by electrochemical and gravimetric methods. In the presence of air, the corrosion rate for the Hastelloy C-276 in the molten salt was found to diminish with immersion time and converges around $50 lm per year after 4 weeks of immersion at 500°C, which is close to the value $40 lm per year obtained using the electrochemical method at 500°C. For anaerobic corrosion rate estimation, the corrosivity of an alloy sample was examined by immersing in molten salt inside a sealed quartz container without any contact with air, which is possible because the vapor pressure of the eutectic molten salt is only about 0.7 atm at 800°C. The corrosion rate of the Hastelloy C-276 was only 10 lm per year in the molten salt in the absence of air at 800°C, which is extremely low compared to 500 lm per year in conducting corrosion studies in the presence of air at 800°C. The Hastelloy coupons after immersion testing in the absence of air have then been examined also by SEM, and the images did not show any http://dx.

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“…The (Fe, Cr) 3 O 4 spinel formed via the following reactions:

2 Cr + 3 O^{2 -} \Leftrightarrow 3 {Cr}_{2} O_{3} + 6 e^{-}

Fe + {Cr}_{2} {normalO}_{3} + {normalO}^{2 -} \Leftrightarrow Fe {Cr}_{2} {normalO}_{4} + 2 {normale}^{-} .

…”

Section: Resultsmentioning

confidence: 99%

Effects of constant load on corrosion cracking of 304 ASS at 600°C in molten salts

Yang

Yin

et al. 2019

Materials & Corrosion

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The effects of constant load (CL) on corrosion cracking of 304 austenitic stainless steel (ASS) in molten salts (binary nitrate salts, 60 wt% NaNO 3 , and 40 wt% KNO 3 ) were investigated. A pair of novel clamping fixture was designed to fix the tensile sample, making the gauge section immersed in molten salts. The CL tensile tests were applied with the initial stress of 212 MPa and the temperature of 600°C. Optical microscopy, scanning electron microscopy, and energy dispersive spectroscopy were employed to characterize the deformation behavior and corrosion features. The results show that corrosion of 304 ASS in molten salts was aggravated by the continuous deformation due to the cracking of protective oxide scale. Grain boundaries were oxidized and weakened by the molten salt, leading to a crack propagating. Compared with the creep test result, a reduced rupture life of 304 ASS under constant loading in molten salts was observed.

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Corrosion of alumina‐forming austenitic steel in molten nitrate salts by gravimetric analysis and impedance spectroscopy

Cited by 71 publications

References 18 publications

High temperature corrosion in molten solar salt: The role of chloride impurities

High temperature corrosion in molten solar salt: The role of chloride impurities

Vapor pressure and corrosivity of ternary metal-chloride molten-salt based heat transfer fluids for use in concentrating solar power systems

Effects of constant load on corrosion cracking of 304 ASS at 600°C in molten salts

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