High-Temperature Corrosion of a Nickel-Based Alloy in a Molten Chloride Environment - The Effect of Thermal and Chemical Purifications

Anna Mortazavi, Youyang Zhao, Mohsen Esmaily, Antoine Allanore, Judith Vidal, Nick Birbilis

Research output: Contribution to journalArticlepeer-review

15 Scopus Citations

Abstract

There is currently an ever-increasing demand for higher process efficiencies in next generation (Gen3) concentrating solar power (CSP). Higher process efficiencies may be procured by increasing the operating temperature, and simultaneously, minimizing the degradation of materials used for construction of CSP plants (e.g., piping, thermal storage tanks, solar receivers and heat exchangers). Thus, understanding materials corrosion in the presence of molten salt mixtures used as thermal energy storage media and heat transfer fluids is indispensable for CSP development. The present paper provides insights into the effects of salt purification on the corrosion of a nickel-based alloy (Haynes 230) isothermally exposed to a stagnant chloride-based salt mixture at 800 °C. The MgCl2-based salt mixture was thermally dehydrated and chemically treated with (0.1 and 0.5 wt %) elemental magnesium. Results reveal the electrochemical nature of the corrosion process, and the formation of corrosion products such as oxides (MgO, MgCr2O4, and MgAl2O4) and nitrides (CrN) on the alloy surface and in sub-surface regions. Magnesium additions enhanced the ability to resist corrosion by reducing the concentration of impurities (H2O, MgOH+, OH species) and polarizing the alloy surface. The formation of nitrides in all cases studied indicates the impact of using nitrogen as a protective gas in the system. Results also reveal that a single step treatment of the salt using metallic Mg could be considered as a measure to control the salt's impurity level, e.g., if required for system control.

Original languageAmerican English
Article numberArticle No. 111542
Number of pages17
JournalSolar Energy Materials and Solar Cells
Volume236
DOIs
StatePublished - Mar 2022

Bibliographical note

Publisher Copyright:
© 2021 Elsevier B.V.

NREL Publication Number

  • NREL/JA-5700-81249

Keywords

  • Cathodic protection
  • Concentrating solar power
  • High-temperature corrosion
  • Magnesium
  • Oxidation and nitridation

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