Abstract
Hot corrosion tests of alumina (Al2O3) and carbon silicate (SiC) ceramics exposed to KCl–NaCl molten salt were performed at high temperatures (700 and 800°C) and for long times (100–400 h) in order to improve the reliability of tanks and heat exchangers for molten salts. The samples were tested by being immersed in molten salt and under salt vapor. Basic corrosion data, such as the corrosion product, surface conditions, and 4-point bending strength were acquired. In the case of the Al2O3 ceramics, neither corrosion products nor a significant roughness of the Al2O3 particles was observed. In the case of the SiC ceramics, the observed corrosion product was SiO2, and considerable roughness was found at the surface of the immersed sample. The surface roughness became more pronounced as the corrosion temperature and time increased. On the other hand, a SiO2 thin film was observed on the surface of the sample that was exposed to salt vapor. A significant strength decrease was not observed for the two types of Al2O3 and SiC ceramics. Therefore, Al2O3 ceramics are expected to represent a suitable container material for molten salts. On the other hand, predicting the lifetime of the material is necessary if SiC ceramics are intended to be used.
