Fabrication Processes of Annular and Thin-walled Al-UO2 Dispersion Pellet

The hot-press and free pressure sintering processes of the annular and thin-walled Al-20%UO₂ dispersion pellets and their properties were studied. The vacuum free pressure sintering can produce good pellet, but the pellets produced by vacuum hot-press sintering may easily encounter the problems of low density and cracks. The granulation of Al powders by PVA solution method and two-step mixing process with UO₂ powders were used to fabricate the green body of Al-20%UO₂ with density of 93.45%TD at 550 MPa, and it’s outside diameter increases 0.455% and inside diameter increases 0.194% compared to diehole size. The Al-20%UO₂ dispersion pellet was sintered by vacuum free pressure process at 490 ℃ and 4×10^-2 Pa for 1 h with density of 94.54%TD, and outside diameter of （53.230±0.006） mm with swelling rate of 0.415%, and inside diameter of （45.506±0.017） mm with swelling rate of 0.278%. These pellets can be loaded into clad tube directly and sealed to assemble target without grinding.