Structural stability and neutron-shielding capacity of GdBO3-Al18B4O33 composite ceramics: Experimental investigation and numerical simulation

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.