Corrosion resistance of HR3C to a carbonate molten salt for energy storage applications in CSP plants

Abstract

This paper studies the behaviour of austenitic steel HR3C in a eutectic ternary Li2CO3-Na2CO3-K2CO3 molten salt mixture through an isothermal immersion test at 700 °C for 2000 h. To this aim various techniques were used in order to examine the effects of long-term, high-temperature corrosion processes on the selected substrate. It was found that the corrosion products were arranged in a multilayer structure, with LiFeO2, LiCrO2, NiO and FeCr2O4 being the main compounds in the different layers. The composition of the remaining salt after the corrosion tests was also studied, the chromium increase being one of the main points to highlight. The results suggested that longer immersion tests should be carried out to clearly confirm the suitability of HR3C for solar thermal applications.