Preparation of yttria-stabilized zirconia-ceria kernels as fuel precursors using internal gelation

Ceria-doped yttria-stabilized zirconia kernels were prepared by internal gelation and the effect that the concentration of HMTA and urea used in the initial broth had on the structure and properties of the gel was studied. Most combinations of urea and HMTA were found to provide gels with a smooth surface, which were assumed to be dense. However, a high quantity of urea and a low quantity of HMTA generated a gel with a rough surface, which was assumed to be porous and limited the formation of cracks during the thermal treatment of kernels. These kernels were then compacted using a repressing method whereby pellets with a sintered density up to 86% TD were formed. It was also found that the presence of urea is necessary to obtain good mechanical properties. (orig.)