Nickel superalloys are the preferred containment materials for TES systems; however, these superalloys are sometimes susceptible to corrosion because of sensitisation resulting from heating or stress. Inconel 601 is a nickel-chromium alloy specifically developed for high temperature purposes.
Assoc. Prof. Geoffrey Will’s team investigated the impact of the molten salt environment in TES systems on Inconel 601 performance. A combination of microstructural, electrochemical, and Kelvin probe force investigations were carried out to analyse the impact of cold-working versus annealing on the interaction of Inconel 601 and a eutectic molten carbonate salt at 450° C for TES.
The research found that annealed Inconel 601 performed better than the cold-worked material with a lower corrosion current density value, a reduction in internal lattice strains, a more homogeneous microstructure, and a higher homogeneity of the surface microstructure.
Stainless steel 316 and Inconel 690 are next on the list for similar studies to further the understanding of these superalloys and develop higher performance materials for use in TES systems in future solar power stations.