Mass fabrication of Li2TiO3–Li4SiO4 ceramic pebbles with high strength by facile centrifugal granulation method

Abstract

AbstractThe bi‐phase Li2TiO3–Li4SiO4 ceramic pebbles have been considered a promising breeder to realize the tritium self‐sustainment in the blanket. However, up to now, the reported ceramic pebbles have the disadvantages of low yield, poor crushing load, and loose internal structure, which cannot meet the practical application requirements. In this work, the Li2TiO3–Li4SiO4 ceramic pebbles with excellent mechanical properties were fabricated successfully via the centrifugal granulation method with the assistance of introducing a spray‐drying process, simulating particle trajectory by discrete element software and improving bonding interface between core and shell with ethylene glycol. The composition, microstructure, and inner structure of the Li2TiO3–Li4SiO4 ceramic pebbles were investigated, respectively, through X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and X‐ray computed tomography (CT). It can be found that the employment of the ethylene glycol solution on the surface of Li2TiO3 can make the core and the shell combine well. Moreover, the effect of the rolling speed of the Li2TiO3–Li4SiO4 ceramic pebbles was investigated via discrete element method (EDEM) simulation and experiments. The experimental results displayed that the Li2TiO3–Li4SiO4 ceramic pebbles sintered at 1100°C for 2 h have a uniform diameter of 1 mm, a good sphericity of 0.97, and an excellent crushing load of 82.4 N, which are superior to those pebbles that obtained by using the traditional wet methods. Moreover, the CT results showed that the appropriate porosity of the core was 3.21% and of the shell was 10.73%. Therefore, the simple centrifugal granulation method can be applied to prepare the Li2TiO3–Li4SiO4 ceramic pebbles in a large scale and shed a light to investigate the relevant advanced biphasic tritium breeder materials in the future.