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Title: Corrosion resistance of MCrAlX coatings in a molten chloride for thermal storage in concentrating solar power applications

Corrosion evaluations of Incoloy 800 H (In800H) and stainless steel AISI 310 (310SS), in bare and coated conditions, were performed in 34.42 wt% NaCl – 55.47 wt% KCl at 700 °C in a nitrogen atmosphere. This NaCl–KCl composition has a melting point of 657 °C, which makes it suitable for latent-heat thermal energy storage in concentrating solar power applications. Several nickel-based MCrAlX coatings were tested, where M = Ni and/or Co and X = Y, Ta, Hf, and/or Si. Electrochemical testing was carried out to determine corrosion rates. The bare In800H and 310SS alloys corroded rapidly (~2500 and 4500 µm/yr, respectively, assuming uniform corrosion). Concentrating solar power plants need containment materials with a lifetime of at least 30 years; thus, these corrosion rates are excessive. Corrosion mitigation approaches are being investigated to obtain degradation on the order of 20 µm/yr or lower. The lowest corrosion rate of 190 µm/yr was obtained for atmospheric plasma spray NiCoCrAlY coatings pre-oxidized in air at 900 °C for 24 h with a heating/cooling rate of 0.5 °C/min. Metallographic characterization of the corroded surfaces showed that the formation of a uniform thin alumina scale before exposure to the molten chloride system considerably reduced the corrosionmore » of the alloy. However, the rates of corrosion determined herein are considerable, highlighting the relevance of testing materials durability in solar power applications.« less
Authors:
ORCiD logo [1]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Report Number(s):
NREL/JA-5500-68444
Journal ID: ISSN 2397-2106
Grant/Contract Number:
AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
npj Materials Degradation
Additional Journal Information:
Journal Volume: 1; Journal Issue: 7; Journal ID: ISSN 2397-2106
Publisher:
Springer
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 47 OTHER INSTRUMENTATION; molten salts; corrosion; chlorides; coatings; alumina; oxidation
OSTI Identifier:
1394112

Gomez-Vidal, Judith C. Corrosion resistance of MCrAlX coatings in a molten chloride for thermal storage in concentrating solar power applications. United States: N. p., Web. doi:10.1038/s41529-017-0012-3.
Gomez-Vidal, Judith C. Corrosion resistance of MCrAlX coatings in a molten chloride for thermal storage in concentrating solar power applications. United States. doi:10.1038/s41529-017-0012-3.
Gomez-Vidal, Judith C. 2017. "Corrosion resistance of MCrAlX coatings in a molten chloride for thermal storage in concentrating solar power applications". United States. doi:10.1038/s41529-017-0012-3. https://www.osti.gov/servlets/purl/1394112.
@article{osti_1394112,
title = {Corrosion resistance of MCrAlX coatings in a molten chloride for thermal storage in concentrating solar power applications},
author = {Gomez-Vidal, Judith C.},
abstractNote = {Corrosion evaluations of Incoloy 800 H (In800H) and stainless steel AISI 310 (310SS), in bare and coated conditions, were performed in 34.42 wt% NaCl – 55.47 wt% KCl at 700 °C in a nitrogen atmosphere. This NaCl–KCl composition has a melting point of 657 °C, which makes it suitable for latent-heat thermal energy storage in concentrating solar power applications. Several nickel-based MCrAlX coatings were tested, where M = Ni and/or Co and X = Y, Ta, Hf, and/or Si. Electrochemical testing was carried out to determine corrosion rates. The bare In800H and 310SS alloys corroded rapidly (~2500 and 4500 µm/yr, respectively, assuming uniform corrosion). Concentrating solar power plants need containment materials with a lifetime of at least 30 years; thus, these corrosion rates are excessive. Corrosion mitigation approaches are being investigated to obtain degradation on the order of 20 µm/yr or lower. The lowest corrosion rate of 190 µm/yr was obtained for atmospheric plasma spray NiCoCrAlY coatings pre-oxidized in air at 900 °C for 24 h with a heating/cooling rate of 0.5 °C/min. Metallographic characterization of the corroded surfaces showed that the formation of a uniform thin alumina scale before exposure to the molten chloride system considerably reduced the corrosion of the alloy. However, the rates of corrosion determined herein are considerable, highlighting the relevance of testing materials durability in solar power applications.},
doi = {10.1038/s41529-017-0012-3},
journal = {npj Materials Degradation},
number = 7,
volume = 1,
place = {United States},
year = {2017},
month = {9}
}