Corrosion Evaluation Advances for Promising Tes Materials in Alumina Forming Alloys
Abstract
In the present study, new molten-salts are being proposed for Thermal Energy Storage (TES) materials at high temperature, but their corrosion characteristics are not available in the literature. The corrosion issues have to be resolved completely before commercial application of the molten-salts as the HTF in CSP plants. To mitigate corrosion, different alumina forming alloys have been exposed to the most promising molten salts to be proposed for the new storage trends in CSP plants. This paper includes an extended corrosion study for these new developments, including nitrate, carbonate and chloride molten salts. Ni base steels showed a better behavior in the corrosive environments and electrochemical impedance tests showed the formation of a protective layer in the first 24 hours. The gravimetric results and SEM analyses that were performed, confirm the excellent behavior of the steels tested in nitrates and carbonates salts reducing the corrosion ability in these promising novel molten salts compared with the solar salt currently used in solar technology. On the other hand chloride molten salt presents a very aggressive environment and the steels proposed are not recommended for its use as container materials in CSP plants.
Keywords
Thermal energy storage, Molten salt, Corrosion, Electrochemical impedance spectroscopy