Corrosion Behavior of Candidate Materials in Molten LiCl-KCl Salt Under Argon Atmosphere

Abstract

Pyrochemical reprocessing involves the use of molten LiCl-KCl (lithium chloride-potassium chloride) eutectic salt at 773 K for the recovery of uranium and plutonium from spent metallic fuel of fast breeder reactors. The materials selected for such corrosive environments should withstand high temperatures and at the same time offer good corrosion resistance. The present work discusses the corrosion behavior of candidate materials like 2.25Cr-1Mo steel (UNS K21590), 9Cr-1 Mo steel (UNS K90941), Ni-based alloy 600 (UNS N06600), Ni-based alloy 625 (UNS N06625), and Ni-based alloy 690 (UNS N06690) in molten LiCl-KCl eutectic salt at 873 K for various durations under ultrahigh-purity argon atmosphere. Corrosion behavior of partially stabilized zirconia (PSZ) coating on candidate materials also was evaluated. Weight-loss results indicated that the corrosion resistance of the materials increased in the following order: 2.25Cr-1Mo > 9Cr-1 Mo > Ni-based alloys > PSZ coating. PSZ-coated specimens showed better corrosion resistance in molten LiCl-KCl salt when compared with uncoated specimens; however, accidental ingression of oxygen and moisture could result in premature spallation of the coating. Scanning electron microscopy (SEM) examination and grazing incidence x-ray diffraction (GIXRD) analysis of exposed Cr-Mo steels and Ni-based alloys exhibited dealloyed surfaces and corrosion product regions rich in Cr, indicating preferential leaching of Cr. The paper highlights the results of the present investigation.

Corrosion Behavior of Structural Materials in LiCl-KCl Molten Salt by Thermogravimetric Study

“…Ravi Shankar, et al, 7 observed the corrosion resistance of the candidate materials in molten LiCl-KCl salt at 600°C under an inert Ar atmosphere to follow the sequence: 2.25Cr-1Mo > 9Cr-1Mo > nickel (Ni)base alloys. Other researchers 8 also observed similar behavior that high Cr content alloys are prone to faster corrosion in molten salt medium at high temperatures.…”

Concentrating Solar Power Gen3 Demonstration Roadmap

“…Packing materials will need to be determined for either a chloride or carbonate system. Typical graphite-based packing may be compatible with a chloride salt [41]. It is unlikely that carbonatebased salts can use graphite, because a combustion reaction will occur (similar to nitrate behavior).…”

Effect of Deposition Conditions on Phase Content and Mechanical Properties of Yttria-Stabilized Zirconia Thin Films Deposited by Sol-Gel/Dip-Coating

“…Yttria-stabilized zirconia (YSZ) due to its low thermal conductivity, chemical inertness, radiation resistance, and high mechanical properties has been proposed for a wide range of applications in the nuclear industry, such as inert matrix fuel, diffusion barrier to avoid fuel-matrix interaction, sacrificial coatings, and thermal insulator, among others [1][2][3][4][5][6]. However, some of these applications require the deposition of YSZ at low temperatures (for example, 1050 °C on T91 steel or 800 °C on Ni alloys) to avoid phase changes or considerable reductions on mechanical properties on thermolabile substrates [3,7,8].…”