Densification of uranium dioxide fuel pellets prepared by spark plasma sintering (SPS)

An investigation into the influence of processing parameters on densification of UO2 powder during spark plasma sintering (SPS) is presented. A broad range of sintering temperatures, hold time and heating rates have been systematically varied to investigate their influence on the sintered pellet densification process, grain growth, hardness, and Young’s modulus. The results revealed that up to 96% theoretical density (TD) pellets can be obtained at a sintering temperature of 1050 °C for 30 s hold time and a total run time of only 10 min. The resulting UO2 pellets had an average Vickers hardness of 6.4 ± 0.4 GPa and Young’s modulus of 204 ± 18 GPa, which are in excellent agreement with values reported in literature for UO2 processed by other methods.