Expedited spark plasma sintering of high‐density uranium mononitride pellet utilizing U2N3 powder

Abstract The feasibility of a non‐stoichiometric synthesis strategy for uranium mononitride (UN) pellet fabrication is experimentally verified with spark plasma sintering of U 2 N 3 powder in this study. The method removes the denitride process (reduction of U 2 N 3 to UN powder) from the conventional UN pellet fabrication, and it still successfully provided near‐perfect UN stoichiometry and high density (94 %TD). During the spark plasma sintering of U 2 N 3 powder, vacuum pressure increase and powder height, decrease were concurrently measured above ∼1173 K, which indicates the nitrogen gas emission and higher density UN powder formation from the in‐situ decomposition of lower‐density U 2 N 3 powder. The X‐ray diffraction (XRD) analysis on the sintered pellets obtained directly from U 2 N 3 powder showed an excellent match with the existing XRD reference data of UN. The measured density of U 2 N 3 ‐sintered UN pellets was higher (85 %TD) than that of UN‐sintered UN pellets (79 %TD) at relatively low sintering temperature (1773 K). With a higher sintering temperature of 2073 K, high pellet densities (94 %TD) were obtained from both U 2 N 3 and UN powders.