环形薄壁Al-UO2弥散芯块的制备工艺

本文研究了环形薄壁Al-20%UO₂弥散芯块的热压烧结和无压烧结工艺，分析了芯块的性能。研究发现：真空热压烧结弥散芯块的密度较低，且易出现开裂问题；真空无压烧结能制备合格的Al-20%UO₂弥散芯块。对Al粉进行PVA湿法造粒，再与UO₂粉末进行两步均匀混合，在550 MPa成型，Al-20%UO₂压块的成型相对密度达93.45%，外径和内径的弹性后效分别为0.455%和0.194%。在490 ℃、4×10^-2Pa真空无压烧结1 h，Al-20%UO₂弥散芯块的烧结相对密度达94.54%；外径为（53.230±0.006） mm，膨胀率为0.415%；内径为（45.506±0.017） mm，膨胀率为0.278%。芯块不经研磨加工，可直接装管密封制成靶件。

Fabrication Processes of Annular and Thin-walled Al-UO2 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.