Zirconium carbonitride pellets by internal sol gel and spark plasma sintering as inert matrix fuel material

Inert matrix fuel is a fuel type where the fissile material is blended with a solid diluent material. In this work zirconium carbonitride microspheres have been produced by internal sol gel technique, followed by carbothermal reduction. Material nitride purities in the produced materials ranged from Zr(N0.45C0.55) to Zr(N0.74C0.26) as determined by X-ray diffraction and application of Vegard's law. The zirconium carbonitride microspheres have been pelletized by spark plasma sintering (SPS) and by conventional cold pressing and sintering. In all SPS experiments cohesive pellets were formed. Maximum final density reached by SPS at 1700 C was 87% theoretical density (TD) compared to 53% TD in conventional sintering at 1700 C. Pore sizes in all the produced pellets were in the mm scale and no density gradients could be observed by computer tomography.