Processing and characterization of Zr3Si2 for nuclear applications

Zr3Si2 compound, which is not commercially available, was synthesized for use as neutron reflector in the core of the future nuclear power plants: the aim was to get data on basic properties such as thermal properties to be used in reactor design codes. The material was processed in three steps: (i) arc melting of Si granules and Zr sheets, (ii) crushing of the obtained ingot and (iii) hot isostatic pressing. The obtained dense Zr3Si2 bulk sample contained small amount of metastable Zr5Si3 compound. The microstructure exhibited a large grain size distribution (<2–50 μm) but the sample was homogeneous in composition. Thermal expansion measurements showed good dimension stability of the material up to 1273 K, and a thermal expansion coefficient of 8.11 × 10−6 K−1. Heat capacity and thermal diffusivity measurements allowed to calculate thermal conductivity up to 1273 K: it was quite high and slightly increases from 19 W/m·K to 20.5 W/m·K, confirming the metallic feature of Zr3Si2.