The study of thermal properties and oxidation behavior of SiC-UN composite pellets

High density SiC-UN composite pellets were prepared by Spark Plasma Sintering (SPS). Al powders were confirmed as a better sintering aid than Al 2 O 3 +Y 2 O 3 and the density of the composite pellets reached 98.33% of theoretical density (TD). When the SiC content increased above 4.76 wt%, the SiC formed continuous phase in composite pellets and surrounded UN particles. The continuous SiC phase improved the pellets’ thermal conductivity but reduced the oxidation resistance. However, the SiC with low content (<4.76 wt%) and dispersed distribution improved the oxidation resistance owing to formation of dense U-Si-N-O-(C) layer during the oxidation. The oxidation onset temperature (OOT) of 2.46wt%SiC-UN pellets was improved to about 450 °C compared with the 409 °C OOT of UN pellets.