Molten chloride salts possess many attractive properties for use as a coolant and storage medium in advanced nuclear reactors and in concentrated solar power systems. For most common structural alloys selective leeching of chromium into the salt is the dominant form of material degradation in molten halides. For this work, a multi-faceted experimental and computational strategy was used to fundamentally understand Cr dealloying in molten chloride salts. Controlled capsule tests were conducted in which model Ni-Cr alloys were exposed to molten KCl-MgCl<sub>2</sub> at 700-1000°C. Salts were prepared with controlled amounts of oxidizing impurities to understand their effects on corrosion, and alloy microstructures were carefully controlled to isolate diffusion and grain-size effects. X-ray and Raman spectroscopy were used on specifically prepared molten salts to observe the speciation of corrosion products and gain insight into reaction mechanisms. Corrosion-relevant salt systems were thermodynamically modeled with the CALPHAD method to understand corrosion thermodynamics. These models were informed by data gathered from spectroscopic investigation, and benchmarked by salt chemistry data obtained from capsule testing. This talk will report new insights gained into corrosion mechanisms of structural alloys in molten chloride salts. An overview of an interdisciplinary approach to investigating, measuring, and understanding corrosion mechanisms will be presented.<br/>

Holistic approach to understanding alloy degradation in molten chloride salts

2019 Fall National Meeting

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