Studies on the spark plasma sintering of U3Si2: Processing parameters and interactions

Spark plasma sintering (SPS) as a method for fabricating uranium silicide (U₃Si₂) fuel forms has been investigated with a focus on the effect of processing parameters on the achieved density of the final material. The results of the study provide a means to produce varying density pellets by varying the parameters used and allow for the most time effective method for achieving a 95% theoretical density material to be determined. The dwell temperature and pressure applied were found to have the most significant effect on the density achieved, whereas temperature ramp rate was found to have minimal affect and dwell time had the most affect only initially. The interaction of U₃Si₂ with graphite, molybdenum and polyethylene glycol (used as a milling aid) has also been investigate through SPS fabrication. The results determined that graphite was a preferable die liner over molybdenum, but that a carbide layer and interaction region is formed on the periphery of the U₃Si₂. The interaction of polyethylene glycol with U₃Si₂ resulted in a high level of oxide impurities similar to U₃Si₂ manufactured via more conventional methods.