High-temperature stability of CSZ, YSZ, and MSZ ceramic materials in CaCl2-CaF2-CaO molten salt system

This study investigated the high-temperature stability of CSZ, YSZ, and MSZ specimens in a CaCl2-CaF2-CaO molten salt at 1200 degrees C for the application of the materials as oxygen-ion-conducting solid-oxide membrane anodes in the electroreduction process of metal oxides. YSZ exhibited the lowest degradation among the tested specimens in a high-temperature stability test, whereas CSZ showed the highest degradation. The weight loss was not severe with concentrations of CaO up to 10 wt%. CSZ showed peaks for m-ZrO2, YSZ showed peaks for t-ZrO2 and CaZrO3, and MSZ showed peaks for t-ZrO2 and m-ZrO2 in 0 wt% CaO. In the case of 5 wt% CaO, all specimens exhibited m-ZrO2 and CaZrO3 peaks, In the cases of 10 wt% and 20 wt% CaO, CSZ and MSZ showed peaks for CaZrO3, and YSZ showed peaks for m-ZrO2 and CaZrO3. While CSZ and MSZ became significantly looser as the CaO concentration was increased to 10 wt %, YSZ became significantly denser due to the formation of a protective layer and attack dependent on the solubility of CaO in the molten CaCl2. In terms of long-term operation, YSZ was demonstrated to possess superior high-temperature stability compared to CSZ and MSZ, and CaO concentrations from 5 wt% to 10 wt% were found to be significantly more stable than other concentrations. (c) 2018 Elsevier B.V. All rights reserved.