An improved internal gelation process without cooling the solution for preparing uranium dioxide ceramic microspheres

Abstract An improved internal gelation process for the preparation of UO 2 ceramic microspheres with diameter of 790±20 µm is described. The UO 2 ceramic microspheres are prepared by optimizing feed solution compositions and heating up rate during sintering and calcination steps. The two feed solutions Hexamethylenetetramine (HMTA)-urea and UO 2 2+ were mixed just before the drop formation driven by two liquid chromatographs at room temperature without Cooling the Solution. A urea/UO 2 2+ mole ratio of 1.45 is applied to ensure the stability of the solution. After accurate washing steps to wipe out the impurities, good spherical and little cracked UO 2 ceramic microspheres will be obtained at a heating-up rate of 5 K/min during sintering and calcination. Different from the traditional methods reported previously, solution which is not cooled is employed during the improved process in this paper.