Fabrication and characterisation of ZrSi2 ceramics via reactive hot-pressing

ABSTRACT ZrSi2 was fabricated via reactive hot-pressing technique for 45 min at 1250°C and 1350°C, respectively. The hot-pressed sample exhibited Vickers hardness of 10.93 ± 0.32 GPa and indentation fracture toughness of 3.16 ± 0.54 MPa.m1/2. Thermal conductivity (RT-2.99 W (m.K)−1) and diffusivity (RT–18.2 mm2 s−1) of the sample decreased with increasing temperature due to phonon scattering. Oxidation studies were carried out for the hot-pressed samples from 1000°C to 1200°C for 5, 48 and 100 h in air. The oxidation test results showed that ZrSi2 followed selective oxidation with Si diffusing into the oxide layers at high temperatures. At 1200°C, the surface of ZrSi2 oxidised completely to form a high-temperature stable phase, zircon (ZrSiO4). The autoclave test at 250°C and 250 bar shown negligible mass gain (∼0.022 g) which suggests the usage of ZrSi2 for nuclear fuel cladding applications.