Study on compatibility between silicon carbide and solid breeding materials under neutron irradiation

Compatibility of monolithic silicon carbide (SiC) with ternary lithium ceramics (Li_1-x AlO_2-y, Li_2-x TiO_3-y, Li₂-_xZrO_3-y and Li_4-xSiO_4-y) under irradiation of neutrons at high temperatures was studied. Disk samples of SiC in contact with sintered ternary lithium ceramics were irradiated in High Flux Isotope Reactor (HFIR) at 800 °C to 5.9 displacements per atom (dpa). Chemical reactions of SiC as determined by appearance of the surface were relatively less significant for the systems of SiC/Li_1-x AlO_2-y and SiC/Li_2-x TiO_3-y, whereas some bonding likely due to chemical reaction between SiC and the lithium ceramics and broken samples were observed in the systems of SiC/Li_2-x ZrO_3-y and SiC/Li_4-xSiO_4-y . The effect of lithium burnup due to the (n, α) nuclear reaction was also examined by using samples of lithium ceramics whose lithium ratio was hypo-stoichiometric in the fabrication process. More reaction products were observed on the surface of β-SiC in contact with Li_1-x AlO_2-y having the lower lithium ratio (Li/Al). It was considered that the formation of LiAl₅ O₈ phase due to lithium loss could deteriorate the compatibility of the SiC-Li_1-x AlO_2-y system.