Sulfate corrosion and phosphate passivation of Ni-based alloy in supercritical water

Shuwei Guo; Donghai Xu; Guanyu Jiang; Yang Guo; Zefeng Jing

doi:10.1016/j.supflu.2022.105564

Sulfate corrosion and phosphate passivation of Ni-based alloy in supercritical water

Shuwei Guo
, Donghai Xu
, Guanyu Jiang
, Yang Guo
, Zefeng Jing

School of Energy and Power Engineering

Research output: Contribution to journal › Article › peer-review

14 Scopus citations

Abstract

Corrosion behavior of Ni-based alloy Inconel 625 in sulfate- and phosphate-containing SCW, and the mechanism of phosphate passivation acting as a corrosion inhibitor were investigated in this work. Sodium phosphate passivation treatment reduced the corrosion weight gains in oxygenated and pure SCW by 68.4% and 77.4%, respectively. The synergistic effect of high concentration of sulfate ions and oxygen on the alloy surface caused occurrence and expansion of pitting corrosion. NiCr₂O₄, NiO, Cr₂O₃, divalent and trivalent iron compounds could stably exist on the surface of sodium phosphate-passivated sample before and after exposure to oxygenated SCW. CrPO₄, FePO₄ and Ni₃(PO₄)₂, which were closely and uniformly distributed on the alloy surface, stably existed in SCW and served as a barrier layer for the alloy matrix. These oxides could inhibit the diffusion of metal cations and oxygen anions near the interface to improve corrosion resistance.

Original language	English
Article number	105564
Journal	Journal of Supercritical Fluids
Volume	184
DOIs	https://doi.org/10.1016/j.supflu.2022.105564
State	Published - May 2022

Keywords

Corrosion
Corrosion resistance
Passivation
Sodium phosphate
Sodium sulfate
Supercritical water

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10.1016/j.supflu.2022.105564

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@article{b64e5724a46f4923908ae5f3738d1e35,

title = "Sulfate corrosion and phosphate passivation of Ni-based alloy in supercritical water",

abstract = "Corrosion behavior of Ni-based alloy Inconel 625 in sulfate- and phosphate-containing SCW, and the mechanism of phosphate passivation acting as a corrosion inhibitor were investigated in this work. Sodium phosphate passivation treatment reduced the corrosion weight gains in oxygenated and pure SCW by 68.4\% and 77.4\%, respectively. The synergistic effect of high concentration of sulfate ions and oxygen on the alloy surface caused occurrence and expansion of pitting corrosion. NiCr2O4, NiO, Cr2O3, divalent and trivalent iron compounds could stably exist on the surface of sodium phosphate-passivated sample before and after exposure to oxygenated SCW. CrPO4, FePO4 and Ni3(PO4)2, which were closely and uniformly distributed on the alloy surface, stably existed in SCW and served as a barrier layer for the alloy matrix. These oxides could inhibit the diffusion of metal cations and oxygen anions near the interface to improve corrosion resistance.",

keywords = "Corrosion, Corrosion resistance, Passivation, Sodium phosphate, Sodium sulfate, Supercritical water",

author = "Shuwei Guo and Donghai Xu and Guanyu Jiang and Yang Guo and Zefeng Jing",

note = "Publisher Copyright: {\textcopyright} 2022 Elsevier B.V.",

year = "2022",

month = may,

doi = "10.1016/j.supflu.2022.105564",

language = "英语",

volume = "184",

journal = "Journal of Supercritical Fluids",

issn = "0896-8446",

publisher = "Elsevier B.V.",

}

TY - JOUR

T1 - Sulfate corrosion and phosphate passivation of Ni-based alloy in supercritical water

AU - Guo, Shuwei

AU - Xu, Donghai

AU - Jiang, Guanyu

AU - Guo, Yang

AU - Jing, Zefeng

PY - 2022/5

Y1 - 2022/5

N2 - Corrosion behavior of Ni-based alloy Inconel 625 in sulfate- and phosphate-containing SCW, and the mechanism of phosphate passivation acting as a corrosion inhibitor were investigated in this work. Sodium phosphate passivation treatment reduced the corrosion weight gains in oxygenated and pure SCW by 68.4% and 77.4%, respectively. The synergistic effect of high concentration of sulfate ions and oxygen on the alloy surface caused occurrence and expansion of pitting corrosion. NiCr2O4, NiO, Cr2O3, divalent and trivalent iron compounds could stably exist on the surface of sodium phosphate-passivated sample before and after exposure to oxygenated SCW. CrPO4, FePO4 and Ni3(PO4)2, which were closely and uniformly distributed on the alloy surface, stably existed in SCW and served as a barrier layer for the alloy matrix. These oxides could inhibit the diffusion of metal cations and oxygen anions near the interface to improve corrosion resistance.

AB - Corrosion behavior of Ni-based alloy Inconel 625 in sulfate- and phosphate-containing SCW, and the mechanism of phosphate passivation acting as a corrosion inhibitor were investigated in this work. Sodium phosphate passivation treatment reduced the corrosion weight gains in oxygenated and pure SCW by 68.4% and 77.4%, respectively. The synergistic effect of high concentration of sulfate ions and oxygen on the alloy surface caused occurrence and expansion of pitting corrosion. NiCr2O4, NiO, Cr2O3, divalent and trivalent iron compounds could stably exist on the surface of sodium phosphate-passivated sample before and after exposure to oxygenated SCW. CrPO4, FePO4 and Ni3(PO4)2, which were closely and uniformly distributed on the alloy surface, stably existed in SCW and served as a barrier layer for the alloy matrix. These oxides could inhibit the diffusion of metal cations and oxygen anions near the interface to improve corrosion resistance.

KW - Corrosion

KW - Corrosion resistance

KW - Passivation

KW - Sodium phosphate

KW - Sodium sulfate

KW - Supercritical water

UR - https://www.scopus.com/pages/publications/85126387366

U2 - 10.1016/j.supflu.2022.105564

DO - 10.1016/j.supflu.2022.105564

M3 - 文章

AN - SCOPUS:85126387366

SN - 0896-8446

VL - 184

JO - Journal of Supercritical Fluids

JF - Journal of Supercritical Fluids

M1 - 105564

ER -

Sulfate corrosion and phosphate passivation of Ni-based alloy in supercritical water

Abstract

Keywords

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