Feasibility of Li4SiO4 pebbles by drip casting and preliminary characterization

Open issues for fusion reactor technology are related to the breeder material to be used for the nuclear fusion reaction. Despite in the last decades several studies were carried out, the selection, characterization and reliability of breeder material are still open issues. In this study, the attention is focused on the production of lithium orthosilicate (Li4SiO4) by means of drip casting method. The feasibility of this method was verified using an experimental rig designed and constructed purposely at the Pisa University, Department of Civil and Industrial Engineering (DICI). The green pebbles were produced starting from a suspension of Li4SiO4 precursors (i.e. LiOH and Si(OCH2CH3)4) prepared by sol-gel method. These pebbles were dried at 40 °C for 4 h, and then sintered in air at 900 °C for 10 h. The morphological and physical properties of the obtained pebbles were analyzed by scanning electron microscope (SEM), X-ray and compression tests. The X-ray results showed the main characteristic peaks of Li4SiO4 crystalline phase and small peaks attributable to calcium metasilicate, while the SEM analysis showed a homogeneous and uniform structure of the pebbles. The obtained preliminary results showed the feasibility of dripping at room temperature and provided further useful information for the optimization of the process.