LAUSR

Abstract The effects of processing parameters on the properties of SiC matrices and fully ceramic microencapsulated (FCM) fuel pellets were investigated with a small amount of additives by hot pressing. The increases in the applied pressure as well as the sintering time were beneficial in improving the thermal conductivity of the SiC matrix and FCM pellets. Tristructural isotropic (TRISO) particles without an outer pyrolytic carbon layer are not suitable for processing FCM pellets because of the corrosion of the chemical-vapor-deposited SiC layer by the additive-derived liquid phase during sintering. The FCM pellet sintered with 2.71 wt% AlN–Y2O3–Sc2O3–MgO additives at 1870 °C for 4 h under 30 MPa in argon exhibited an excellent thermal conductivity (61.7 Wm-1 K-1 at a TRISO particle content of 43.3%), owing to the (i) reduced amount of additives, (ii) high sintered density (residual porosity ∼ 0.4%), and (iii) highly thermally conductive SiC matrix (105.0 Wm-1 K-1).