Fabrication of Li₄SiO₄ Pebbles Using Slurry Droplet Wetting Method for Solid Breeding Material

Lithium orthosilicate (Li₄SiO₄) pebbles are the primary candidate breeder for the Korean Helium-Cooled Solid Breeder test blanket module because of their superior overall performance qualities such as reasonable lithium atom density, favorable tritium release behavior, low activation property, and chemical stability. The aim of this study is to develop a fabrication method for Li₄SiO₄ pebbles with high sphericity and stable micro-crystalline structure. Li₄SiO₄ slurry was prepared by mixing Li₄SiO₄ powder and polyvinyl alcohol (PVA) solution. The Li₄SiO₄ gel-spheres were made by dropping slurry mixture into hydrogen peroxide (H₂O₂) solution. The gel-spheres were floated up to the surface of the H₂O₂ solution after staying at the bottom for a while and then aged on the surface of the H₂O₂ solution. The gel-spheres were dried at room temperature and sintered at several temperatures for 4 hours in air atmosphere. The sintered pebbles kept the shape of spheres during the sintering process in spite of shrinkage. Furthermore, the pebbles had relatively high sphericity. Also, the effects of PVA content and sintering temperature on the properties of the Li₄SiO₄ pebbles were investigated.