Corrosion Evaluation of Austenitic and Duplex Stainless Steels in Molten Carbonate Salts at 600 °C for Thermal Energy Storage

Next-generation concentrated solar power (CSP) plants are required to operate at temperatures as high possible reach a better energy efficiency. This means significant challenges for the construction materials in terms of corrosion resistance, among others. In present work, behavior molten eutectic ternary Li2CO3-Na2CO3-K2CO3 mixture 600 °C was studied three stainless steels: an austenitic grade AISI 301LN (SS301) and two duplex grades, namely 2205 (DS2205) 2507 (DS2507). Corrosion tests combined with complementary microscopy, microanalysis mechanical characterization techniques were employed determine kinetics steels oxide scales formed on surface. The results showed that all exhibited close parabolic law, their rates increased following order: DS2507 < SS301 DS2205. analyses evidenced arranged multilayer system LiFeO2, LiCrO2, FeCr2O4 NiO main compounds. While Ni-rich inner layer presented good adhesion metallic substrate, outer by LiFeO2 higher concentration porosity voids. Both Cr Ni contents defects crucial resistance each steel. Among materials, super steel is found be most promising alternative thermal storage those structural components CSP plants.