LAUSR

Abstract There is an urgent demand for advanced neutron-shielding materials that can be particularly used at extremely high temperatures in nuclear energy system. In this study, GdBO3–Al18B4O33 composite ceramics (GACCs) were successfully fabricated by the pressureless sintering of Al4B2O9 and Al2O3 using different firing temperatures and varying quantities of Gd2O3 used as the neutron-shielding agent. The properties of the obtained samples, including the crystalline phases, microstructure, thermophysical properties, and neutron-shielding capacity, were studied systematically. The structural stability determined by thermal cycle tests is reassessed based on the thermal stress caused by the mismatch between the thermal expansion coefficients of multiple phases in the material system, and it is further verified via numerical simulations performed using the finite element method. Moreover, the influence of the sample thickness and dispersion density of Gd on the shielding capacity of the material were also investigated and parameterised to guide the design of borate-based shielding materials. The results suggest that GACCs are promising candidates for high-temperature structural materials and excellent neutron-shielding materials in novel nuclear systems.