Potential–temperature (E–T) diagrams for iron, nickel, and chromium in sulfate solutions up to 473 K

The work presented in this review paper is part of a project to investigate corrosion degradation of steam generator (SG) tubing and tube support materials by sulfur compounds at reduced or intermediate oxidation levels (designated here as S x ). The stability of these S x species in aqueous solutions is discussed, and the electrochemical and chemical interactions between S x and metallic surfaces and the subsequent impact of these interactions on metal corrosion are reviewed. Factors influencing S x -induced uniform corrosion, passivity breakdown and stress corrosion cracking (SCC) considered here include: pH, electrode potential, temperature, S x species, alloy compositions and other impurity ions like Cl − .

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“…2concentration increased from 0 M to 0.015 M. 41 These results indicate that SO 4 2is the aggressive anion in mixed Cland SO 4…”

Section: Factors That Influence S X −Induced Passivity Degradationmentioning

confidence: 60%

“…The advantages of these diagrams are their capabilities of presenting the phase stability as a function of temperature. However, only SO 4 2− was considered in the work, 41 and no other important S x species were taken into consideration.…”

Section: ) S−h 2 Omentioning

confidence: 99%

Review—Factors Influencing Sulfur Induced Corrosion on the Secondary Side in Pressurized Water Reactors (PWRs)

Xia

Behnamian

Luo

2019

J. Electrochem. Soc.

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“…Figure 9 shows the calculated results of the distributions of pH value within the pore of the nano-scale structure at different nitriding times. According to the potential-pH diagram of Fe-H 2 O and related studies [53,54], it is known that iron is susceptible to severe corrosion at room temperature when the pH of chlorine-containing solutions is around 3 to 3.5. The decrease rate of pH was fastest in the local micro-zone of AH32 steel with 1 h nitriding.…”

Section: Nitriding Timementioning

confidence: 99%

Hydrophobic durability and anti-corrosion of plasma nitriding layer: Evolution mechanisms of corrosion behavior under variations in local hydrochemistry

Zhao

Chen

Jin

et al. 2023

Mater. Res. Express

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Mechanisms for the effects of nitrogen on the durability of hydrophobic and corrosion resistance of modified layers prepared on the surface of AH32 steel by plasma nitriding have been investigated. It was found that plasma nitriding can significantly improve the hydrophobicity of AH32 steel. All the contact angles (CAs) of the AH32 steel with 1 h, 3 h and 5 h nitriding were higher than 120o, which had excellent hydrophobicity. The acidification degree of the solution within the nitriding layer’s micro-zone was effectively reduced due to the dissolution of nitrogen. The micro-nano structures of the nitriding layers corroded severely after 15 days of exposure to NaCl solution. When the nitriding time is extended to 5 h, the acidification degree of the solution was intensified due to the enhanced blocking effect, and the nitrogen in the nitriding layer saturated that cannot provide enough nitrogen ions to offset the acidification of the solution, so the durability decreased instead. In comparison, the modified layer with 3 h nitriding in this study had the best durability and long-term service protective effect on AH32 steel.

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“…Theoretical calculations made by Marcus and Protopopoff (Marcus and Protopopoff, 1993; Marcus and Protopopoff, 1997a; Marcus and Protopopoff, 1997b; Protopopoff and Marcus, 2003) considered S adsorbed on Fe, Ni, Cr, or Cu in water at 25 and 300°C, as shown in Figure 2. Nickchi and Alfantazi (2013) used E −Temperature ( E − T ) diagrams to evaluate the thermodynamic stability of metal (Fe, Ni, Cr)-H 2 O systems at temperatures up to 200°C, and studied the corrosion behavior of high purity Fe, Ni, and Cr in NaSO 4 solutions. Open circuit potential and polarization resistance data demonstrated that the diagrams were viable and useful.…”

Section: The Stability Of Sulfur Speciesmentioning

confidence: 99%

Effects of reduced sulfur on passive film properties of steam generator (SG) tubing: an overview

Xia

Luo

2019

ACMM

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Purpose Corrosion is considered as one of the issues that threaten the safe operation of steam generator (SG) tubing. Some sulfur-related specie can cause corrosion degradation of SG tubing. Sulfur-induced corrosion of SG alloys in high temperature and high-pressure water is one of the most complicated processes. The purpose of this study is to study the effect of reduced sulphur on passive film properties of steam generator (SG) tubing. Design/methodology/approach In this paper, the effects of reduced sulfur on passive film properties of SG tubing were reviewed from the aspects of thermodynamic calculations and experimental. Findings Thermodynamic calculations are mainly presented by E-pH diagrams, volt equivalent diagrams and species distribution curves. The stability of sulphur species highly depends on temperature, solution pH, and electrochemical potential. Experimental data indicated that reduced sulfur species can interact with the passive film, which led to changes in film thickness, film structure, semiconductivity and pitting growth rate. Originality/value The state-of-the-art discussed in this paper gives basis for resolving engineering problems regarding with sulfur-induced corrosion.

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Potential–temperature (E–T) diagrams for iron, nickel, and chromium in sulfate solutions up to 473 K

Cited by 11 publications

References 49 publications

Review—Factors Influencing Sulfur Induced Corrosion on the Secondary Side in Pressurized Water Reactors (PWRs)

Review—Factors Influencing Sulfur Induced Corrosion on the Secondary Side in Pressurized Water Reactors (PWRs)

Hydrophobic durability and anti-corrosion of plasma nitriding layer: Evolution mechanisms of corrosion behavior under variations in local hydrochemistry

Effects of reduced sulfur on passive film properties of steam generator (SG) tubing: an overview

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