Characterization of ceramic coatings of melting crucible for metal fuel

Traditionally, graphite has been the base material for a lot of crucible work, and metallic nuclear fuels, such as the U.Zr/U TRU Zr alloy system used in or proposed for sodium cooled fast reactors (SFR), have been melted and cast in graphite crucibles. However, owing to the high chemical reactivity of uranium, a slurry coated graphite crucible or slurry coated quartz mold has been used to prevent contact with the uranium. In this research, SiC, ZrC, ZrO2, Y2O3, and Y2O3 st. ZrO2 were selected through a literature search as promising candidate coating materials to prevent the chemical reactions and the formation of the reaction phases. These materials have been used as coatings in thermal barrier, high reflectivity, and electronic device applications. Niobium was also selected as a substrate because of its refractory nature, because the coefficient of thermal expansion (CTE) is similar to many of the candidate materials. The microstructure of the coated materials was characterized and thermal cycling tests were performed to investigate the effect of repeated heating and cooling on the contact state of the interface between the coating layer and substrates. Interaction studies were also carried out at an elevated temperature in U-Zr-Ce fuel melt to investigate the refractory of the coating materials