SUMMARY

As next-generation renewable energy technologies like concentrating solar power (CSP) systems operate at ever higher temperatures (HT) to increase efficiency, their structural material and molten salt selection becomes increasingly important. To understand the behavior of structural materials under extreme conditions (above 700°C and immersed in molten chloride salt), this work will investigate the HT thermophysical and corrosion behavior of promising nickel and iron alloys (Ni 201, Haynes 230, Haynes 233, Haynes HR 120, Hastelloy N, Hastelloy C-276, In 625, In 740H, SS310, SS316, Kanthal AF, and Kanthal APM) and ceramic liners (SR-99, WAMBLG, Duro type II, Durrath HD-45, and Clipper DP). HT metrology experiments were performed to calculate temperature-dependent thermal conductivity as a foundation for the project. Temperature-dependent microstructural information will be determined using X-ray Diffraction (XRD). For the HT corrosion tests, alloys and ceramic liners will be immersed in purified molten chloride salt (MgCl2-KCl-NaCl) at several high temperatures (650°, 725°, 800°C) for 100 hours; the corrosion mechanisms and products will be analyzed using SEM/EDS and XRD. These post-test studies will provide a quantitative understanding of the interaction of the materials’ microstructure with the corrosive chloride salt. The extent of protection given by the alumina scale that forms on the ferritic alloy Kanthal APMT will be studied, as well as the impact of impurities on salt wetting on alumina-silica refractories. Using the experimental thermal and corrosion data, a transient heat transfer model of a CSP storage tank will be studied to simulate the proposed materials' thermal performance over time. The proposed work will advance the renewable energy field’s knowledge of structural material behavior at high temperature and under corrosive conditions, which is key to screening candidate alloys and refractory liners for high-performance renewable energy systems.