Stability of calcia-stabilized zirconia in fluoride molten salts under different voltage

Abstract

Rare metals could be produced by using a partially stabilized zirconia (PSZ) solid oxide membrane (SOM). The SOM membrane has to expose to a complex fluoride or chloride flux at high temperature. Besides, the SOM membrance was also affected by the loading voltage. In this work, we discussed the corrosion behavior of Calcia-stabilized zirconia (CSZ) in NaF-KF molten salts with different voltage. The results showed that CSZ tubes were eroded in experiments under different temperatures and voltages. This could be attributed to Ca dissolve out from the CSZ matrix, leading metastable tetragonal phase transfer to monoclinic phase. The corrosion rates of exposed to molten and the influence of voltage were also studied, and it was shown that the grain boundaries on the surface were mostly damaged after only 1 h corrosion. However, the CSZ tube could work in molten salts at least 50h. The effect of loading voltage, which could greatly enhance the corrosion behavior, was also studied. The corrosion mechanism of CSZ with different condition was discussed combining microstructures of surface and cross section, EDS and XRD analysis. Based on this work, we could determine the service life of the CSZ tubes and the voltage used in the produced process of rare metals.