Expedited Spark Plasma Sintering of High‐density UN Pellet utilizing U₂N₃ Powder

Abstract

The feasibility of a non‐stoichiometric synthesis strategy for UN pellet fabrication is experimentally verified with spark plasma sintering of U₂N₃ powder in this study. The method removes the denitride process (reduction of U₂N₃ 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 SPS of U₂N₃ 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 U₂N₃ powder. The XRD analysis on the sintered pellets obtained directly from U₂N₃ powder showed an excellent match with the existing XRD reference data of UN. The measured density of U₂N₃‐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 U₂N₃ and UN powders.

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