Fabrication of uranium monosulfide

Uranium sulfide-one of the potential high-temperature nuclear fuels-was prepared by the reaction of uranium with H2S gas followed by homogenization at high temperature Resulting powders of two different grain sizes (specific surface area of 0.37 and 0.62mm2/g) were separately sintered at 1, 400°-2, 000°C in vacuum. Sintering was found to proceed above 1, 400°C, and with a sintering temperature of 1, 750°C and compacting pressure of 4t/cmcm2, produds of 88-91% theoretical density were obtained with the 0.37mm2/g powder and 94-97% theoretical density with the 0.62mm2/g powder. A discussion is given of the effect on densification brought by differences in compacting pressure, in temperature and duration of sintering, and in heating rate. The microstructures of the sintered bodies were observed by microscope, and the average grain size, shrinkage and Vickers hardness were determined. It was found that UOS contained as impurity in the US contributed to producing high density sintered US.