Fully stabilized‐zirconia is proposed as an inert matrix for next‐generation nuclear fuels. This study presents the application of microwave technology for lowering the sintering temperature of 8 mol% yttria–zirconia (8YZ) to minimize the loss of volatile actinides that will be incorporated into the fuels. Direct microwave sintering results were compared with microwave‐hybrid and conventionally sintered samples. Direct Microwave Sintering of 8YZ showed a reduction of 300°C in temperature required for full densification when compared with conventional sintering. A difference of 200°C was observed with microwave‐hybrid sintering. Despite these differences in processing temperatures, the variations in resulting properties were negligible.

Densification of ceramic materials with microwave energy is being considered as an alternative means to conventional methods. Using microwave processing for sintering ceramics, many researchers have observed higher densities at lower temperatures, as compared with conventional sintering methods. Microwave sintering technology is under investigation for fabricating inert matrix materials that would recycle fuel in proposed Generation IV nuclear reactors. This study examined the variation in hardness with density and the changes in microstructure with processing technique and temperature. The 8 mol% Y 2 O 3 -ZrO 2 samples selected for this study were sintered using a conventional furnace, a multi-mode microwave furnace and a single-mode microwave furnace. Microstructural results on 96% theoretically dense samples showed differences in grain size to processing technique (conventional = 1.58 μm, multi-mode microwave = 1.29 μm, and single-mode microwave = 8.86 μm). Vickers hardness tests were performed on select sample groups representative of each processing method. Similarly, dense samples sintered with a conventional furnace yielded a hardness of 5.37 GPa. Whereas, higher hardness values were observed in similarly dense samples that were processed in a multi-mode microwave (9.28 GPa) and single-mode microwave (7.77 GPa). The results obtained in this study favor microwave sintering at low temperature that could eventually find an application in fabricating inert matrix fuels for next generation reactors.

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