Pressureless Rapid Sintering of UO2 Assisted by High-frequency Induction Heating Process.

Heat generation of uranium dioxide (UO₂) powder and its pressureless rapid sintering behaviors have been studied using a high-frequency induction heating apparatus. The porous graphite housing has been used to prevent heat loss and to preheat the uranium oxides, simultaneously. At an elevated temperature, UO₂ powder generated extra heat by itself. The synergism of individual heat generation between the graphite and UO₂ powder could effectively heat the UO₂ to the sintering temperature of 1700°C. Using this process, densification behavior of cylindrical and disk-type UO₂ green pellets according to the heating rate and grain structure of sintered UO₂ pellets were investigated. Rapid sintering caused a large crack around the circumference of the sintered pellet. The formation of cracks could be avoided when the heating rate or sample dimension are properly reduced. A dense and crack-free UO₂ pellet with a relative density of up to 96% was produced within 5 min of the process time. The induction heat sintering process can be a potential candidate for the rapid fabrication of ceramics and composites. [ABSTRACT FROM AUTHOR]