Porous TaC_x ISOL target materials from mould-casted Ta₄AlC₃

Mould casting and sacrificial templating techniques, common in bioceramic technology, were employed to process porous TaC_x ultra-high temperature ceramics intended as novel target materials for isotope separation on-line (ISOL) facilities, aiming primarily at the production of medical radioisotopes. A feedstock of Ta₄AlC₃ MAX phase powder, polyamide spheres and wax was used to obtain different porous TaC_x grades with bimodal pore size distributions. The ‘green’ bodies underwent de-binding and vacuum annealing to decompose the MAX phase, whereas a reference material was also produced from commercial TaC powders. The thermal stability of the porous TaC_x ceramics was assessed at ISOL-relevant conditions by heating in high vacuum up to 2200 °C. The MAX phase-derived TaC_x porous ceramics evolved from biphasic TaC_x/α-Ta₂C to single-phase TaC_x at higher temperatures, due to carbon incorporation. The porous TaC_x microstructure was stable at 2200 °C with a specific surface area stabilizing at ∼0.25 m²/g and thermal conductivity of 1−4 W/m K.