Corrosion of Nickel Alloys in Molten LiCl-KCl Medium Under Cl2 Bubbling

• Published in: Corrosion (Houston, Tex.) Vol. 74; no. 2; pp. 249 - 259
• Main Authors: Ravi Shankar, A., Kamachi Mudali, U.
• Format: Journal Article
• Language: English
• Published: Houston NACE International 01-02-2018
• Subjects: Alloys; Analytical methods; Base metal; Breeder reactors; Bubbling; Chlorine; Corrosion; Corrosion resistance; Corrosion resistant alloys; Corrosion tests; Electron microscopy; Experiments; Fast breeder; Gases; Grain boundaries; Graphite; Heavy metals; Intergranular corrosion; Lithium chloride; Metal fuels; Metal surfaces; Microstructure; Molten salts; Morphology; Nickel; Nickel base alloys; Nuclear fuels; Photomicrographs; Potassium chloride; Purification; Reprocessing; Salts; Scanning electron microscopy; Silicon nitride; Superalloys; Water purification; Weld metal; Welded joints; X rays; X-ray diffraction; X-ray spectroscopy
• ISSN: 0010-9312; 1938-159X
• DOI: 10.5006/2284

Pyrochemical reprocessing utilizing molten chloride salt medium has been considered as one of the best options for the reprocessing of spent metallic fuels from future fast breeder reactors. Purification of molten salt is an important step where chlorine gas is purged in molten LiCl-KCl eutectic salt at 873 K. Materials for manufacturing of vessels and components for salt purification system should possess high corrosion resistance under such a highly corrosive environment. The present paper discusses the corrosion behavior of INCONEL Alloys 600 (UNS N06600), 625 (UNS N06625), and 690 (UNS N06690) and their welds in molten LiCl-KCl eutectic salt at 873 K under Cl2 bubbling. Characterization of the exposed surfaces was performed by using scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy, and glancing incidence x-ray diffraction. The results of the present study indicated that N06600 and N06690 offered better corrosion resistance compared to N06625. Surface morphology of the exposed base metal and weld metal surfaces exhibited intergranular and interdendritic corrosion, respectively, on N06600 and N06625. SEM micrographs clearly indicated that N06690 exhibited uniform dissolution, while N06600 and N06625 exhibited localized attack. The paper highlights the results of the present investigation.