Fabrication of ZrO2-based nanocomposites for transuranic element-burning inert matrix fuel

ZrO2-based composites reinforced with 6.5 vol.% of carbon foam, carbon fiber, and graphite were fabricated using spark plasma sintering, and characterized using scanning electron microscopy and X-ray diffractometry. Their thermal properties were also investigated. The microstructures of the reinforced composites showed that carbon fiber fully reacted with ZrO2, whereas carbon foam and graphite did not. The carbothermal reaction of carbon fiber had a negative effect on the thermal properties of the reinforced ZrO2 composites because of the formation of zirconium oxycarbide. Meanwhile, the addition of carbon foam had a positive effect, increasing the thermal conductivity from 2.86 to 3.38 W m−1 K−1 at 1,100°C. These findings suggest that the homogenous distribution and chemical stability of reinforcement material affect the thermal properties of ZrO2-based composites.